Sectional Anatomy for Imaging Professionals [4 ed.] 9780323595377, 0323595375

Citation preview

YOU’VE JUST PURCHASED

MORE THAN

A TEXTBOOK!

Evolve Student Resources for Kelley’s: Sectional Anatomy for Imaging Professionals, Fourth Edition, include the following: • Image Collection An image collection with approximately 1000 images.

Activate the complete learning experience that comes with each textbook purchase by registering at

http://evolve.elsevier.com/Kelley/sectionalanatomy/ REGISTER TODAY! You can now purchase Elsevier products on Evolve! Go to evolve.elsevier.com/html/shop-promo.html to search and browse for products. 2015v1.0

SECTIONAL ANATOMY For Imaging Professionals FOURTH EDITION LORRIE L. KELLEY, MS, RT(R)(MR)(CT) Associate Professor Emeritus Boise State University Boise, Idaho

CONNIE M. PETERSEN, MS, RT(R)(CT), MS, LPC Former Adjunct Instructor, Radiologic Sciences Program Boise State University Boise, Idaho

3251 Riverport Lane St. Louis, Missouri 63043

SECTIONAL ANATOMY FOR IMAGING PROFESSIONALS, FOURTH EDITION

ISBN: 978-0-323-41487-6

Copyright © 2018, Elsevier Inc. All Rights Reserved. Previous editions copyrighted 2013, 2007, 1997 No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission and further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein).

Notices Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds or experiments described herein. Because of rapid advances in the medical sciences, in particular, independent verification of diagnoses and drug dosages should be made. To the fullest extent of the law, no responsibility is assumed by Elsevier, authors, editors or contributors for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. Library of Congress Cataloging-in-Publication Data Names: Kelley, Lorrie L., author. | Petersen, Connie M., author. Title: Sectional anatomy for imaging professionals / Lorrie L. Kelley, Connie M. Petersen. Description: Fourth edition. | St. Louis, Missouri : Elsevier, [2018] | Identifiers: LCCN 2017056253 (print) | LCCN 2017056842 (ebook) | ISBN 9780323595377 (Ebook) | ISBN 9780323414876 (pbk. : alk. paper) Subjects: | MESH: Anatomy | Magnetic Resonance Imaging | Tomography | Atlases Classification: LCC QM25 (ebook) | LCC QM25 (print) | NLM QS 17 | DDC 612.0022/3—dc23 LC record available at https://lccn.loc.gov/2017056253

Executive Content Strategist: Sonya Seigafuse Content Development Manager: Lisa Newton Senior Content Development Specialist: Danielle M. Frazier Publishing Services Manager: Deepthi Unni Senior Project Manager: Manchu Mohan Design Direction: Brian Salisbury

Printed in the United States of America Last digit is the print number:  9  8  7  6  5  4  3  2  1

Til James, Min beste venn og evig ledsager. Jeg smil hver dag på grunn av deg. Your strength sustains me, your love elevates me, and your faith inspires me. To my greatest treasures: Kristina, Matt, Jennifer, John, Michael, Natalie, Angela, Blair and Jamers, Daniel, Dean, Maren, Evelyn, McKenzie, Jakob, Anders, Alyssa, Margalit, and Porter Your laughter brings me joy, your enthusiasm for learning is contagious, and your support and love for each other is the grandest example of selfless service. Thanks for reminding me to dream. To my parents, Bill and Darhl Buchanan, for sharing your wisdom and encouragement in ways that strengthen and inspire me. To Connie, for your perseverance in collaborating with me through four editions while keeping your sense of humor. And to the many medical professionals who elevate their professions by serving with humility, compassion, and a reverence for life. LLK

Thank you to my family and friends whose guidance, love, and support carried me through my most trying times. I dedicate this book to: My family, Mom, Dad, Brayden, Trinity, Grant, Scott, Kendra, Colton, and Jayden, who are my greatest blessings and who deeply enrich my life with laughter, joy, support, and true love. When I need you most, you never fail to show up with a hug, smile, or words of encouragement. Thank you for your understanding as I focused much of my time working on this fourth edition. You are my heart and soul and I love you dearly. To Lorrie, my friend and colleague for whom I have the utmost admiration. What a true pleasure it has been to work with you all these years. You truly kept me motivated and even when I was most frustrated, you somehow made me laugh. You are amazing. To my colleagues for their gifts of support and wisdom. And to my clients and a group of extraordinary young women who amaze me with their bravery and strength as they strive for greater wellness in their lives. You are truly special. And to the medical professionals who utilize this book in their pursuit of knowledge to improve patient care and advance the field of radiologic sciences. CMP

Reviewers Lisa Fanning, MEd, RT(R)(CT) Chair School of Medical Imaging & Therapeutics Massachusetts College of Pharmacy and Health Sciences University Boston, MA Rebecca Farmer, MSRS, RT(R)(M) Associate Professor of Allied Health and Radiologic Science School of Allied Health Northwestern State University Shreveport, LA

iv

Kathy Kienstra, MAT, RT(R)(T) Associate Professor Program Director, Radiation Therapy Program Doisy College of Health Sciences Saint Louis University St. Louis, MO

Kenneth A. Roszel, MS, RT(R) Program Director Radiology Geisinger Medical Center Danville, PA

Preface This text was written to address the needs of today’s practicing health professional. As technology in diagnostic imaging advances, so does the need to competently recognize and identify cross-sectional anatomy. Our goal was to create a clear, concise text that would demonstrate in an easy-to-use yet comprehensive format the anatomy the health professional is required to understand to optimize patient care. The text was purposely designed to be used both as a clinical reference manual and as an instructional text, either in a formal classroom environment or as a self-instructional volume. Included are close to 1000 high-quality MR and CT images for every feasible plane of anatomy most commonly imaged. An additional 350 anatomic maps and line drawings related to the MR and CT images add to the learner’s understanding of the anatomy being studied. In addition, pathology boxes describe common pathologies related to the anatomy presented, assisting the reader in making connections between the images in the text and common pathologies that will be encountered in clinical practice. Updated tables are used to summarize and organize key information in each chapter. For example, tables that summarize muscle group information include points of origin and insertion, as well as functions, for the muscle structures pertinent to the images the reader is studying.

NEW TO THIS EDITION • Updated content to reflect the latest ARRT and ASRT curriculum guidelines • Expanded images in the lymphatic system • Second color added to the design to make difficult content easier to digest

identifying the desired anatomy during actual clinical examinations. The narrative accompanying these images clearly and concisely describes the location and function of the anatomy in a format easily understood by health professionals. The text is divided into chapters by anatomic regions. Each chapter of the text contains an outline that provides an overview of the chapter’s contents, pathology boxes that briefly describe common pathologies related to the anatomy being presented, tables designed to organize and summarize the anatomy contained in the chapter, and reference illustrations that provide the correct orientation for ease of locating the anatomy of interest.

ANCILLARIES A Workbook and an Evolve site complement the text. When used together, these additional tools create a virtual learning system/reference resource. Workbook: The Workbook provides practice opportunities for the user to identify specific anatomy. The Workbook includes learning objectives that focus on the key elements of each chapter, a variety of practice items to test the reader’s knowledge of key concepts, labeling exercises to test the reader’s knowledge of the anatomy, case studies to provide relevance for clinical applications, and answers to exercises. Student Resources on Evolve: An image collection with approximately 1000 images. Instructor Resources on Evolve: These resources include a test bank with approximately 500 questions and an image collection with approximately 1000 images. Lorrie L. Kelley Connie M. Petersen

CONTENT AND ORGANIZATION The images include identification of vital anatomic structures to assist the health professional in locating and

v

Acknowledgments Many provided encouragement and direction as the compilation of this text commenced. Danielle Frazier and Manchu Mohan had the tiresome duty of encouraging us to meet deadlines, which they did with grace and patience. Sonya Seigafuse had the daunting task of strategically pulling it all together. We are indebted to them for their editorial assistance in seeing this project through completion. We wish to extend our gratitude to everyone who thought the first, second, and third editions had value and to those who took the time to provide constructive criticism and suggestions for further improvements and increased accuracy. And to the many students, peers, and colleagues for providing feedback so that we could see the text from many different perspectives. The following individuals and institutions deserve special acknowledgment: • Chris Hayden for his tremendous patience, knowledge, and time invested in helping us find and create

all of the new CT images for the third edition. And St. Alphonsus Regional Medical Center for providing the CT images. • Mary Pullin from Philips Medical Systems for providing some beautiful MR images. • Dave Arnold and St. Luke’s Regional Medical Center, as well as Kevin Bean and Intermountain Medical Imaging, for providing the majority of the MR images. We owe a debt of gratitude to Marie Dean who provided numerous new illustrations and revised many old drawings creating more accuracy and consistency in the visual presentation of the artwork throughout the text. Lorrie L. Kelley Connie M. Petersen

vii

Table of Contents 1

Introduction to Sectional Anatomy,  1

2

Cranium and Facial Bones,  13

3

Brain,  86

4

Spine,  172

5

Neck,  250

  6

Thorax,  309

  7

Abdomen,  399

  8

Pelvis,  497

  9

Upper Extremity,  568

10

Lower Extremity,  659

ix

CHAPTER

1

Introduction to Sectional Anatomy Iliopsoas muscle Sartorius muscle Femoral Acetabulum head

Tensor fasciae latae muscle Gluteus medius muscle

R Coccygeus muscle

L Rectum

Coccyx

Gluteus maximus muscle

FIG. 1.1  Axial CT of hips.

Sectional anatomy has had a long history. Beginning as early as the 16th century, the great anatomist and artist Leonardo da Vinci was among the first to represent the body in anatomic sections. In the following centuries, numerous anatomists continued to provide illustrations of various body structures in sectional planes to gain greater understanding of the topographical relationships of the organs. The ability to see inside the body for medical purposes has been around since 1895, when Wilhelm Conrad Roentgen discovered x-rays. Since that time, medical imaging has evolved from the two-dimensional (2D) image of the first x-ray to the 2D cross-sectional images of computed tomography (CT) and magnetic resonance imaging (MRI), then to the three-dimensional (3D) imaging techniques used today. These changes warrant the need for medical professionals to understand and identify human anatomy in both 2D and 3D images. Sectional anatomy emphasizes the physical relationship between internal structures. Prior knowledge of anatomy from drawings or radiographs may assist in understanding the location of specific structures on a sectional image. For example, it may be difficult to recognize all the internal anatomy of the pelvis in cross-section, but by identifying the femoral head on the image, it will be easier to recognize soft tissue structures adjacent to the hip (Fig. 1.1).

OBJECTIVES • Define the four anatomic planes. • Describe the relative position of specific structures within the body using directional and regional terminology. • Identify commonly used external landmarks. • Identify the location of commonly used internal landmarks.

• Describe the dorsal and ventral cavities of the body. • List the structures located within the four abdominal quadrants. • List the nine regions of the abdomen. • Describe the gray scale used in CT and MR imaging. • Describe MPR, CPR, SSD, MIP, and VR. • Differentiate between 2D and 3D images.

OUTLINE ANATOMIC POSITIONS AND PLANES, 2 TERMINOLOGY AND LANDMARKS, 2 External Landmarks, 4 Internal Landmarks, 4 BODY CAVITIES, 4

ABDOMINAL AND PELVIC DIVISIONS, 4 Quadrants, 6 Regions, 6 IMAGE ACQUISITION, 7 IMAGE DISPLAY, 7

Copyright © 2019, Elsevier Inc.

MULTIPLANAR REFORMATION AND 3D IMAGING, 8 Multiplanar Reformation (Reformat) (MPR), 8 Curved Planar Reformation (Reformat) (CPR), 8 3D Imaging, 8 1

CHAPTER 1  Introduction to Sectional Anatomy

2

S

ANATOMIC POSITIONS AND PLANES For our purposes, sectional anatomy encompasses all the variations of viewing anatomy taken from an arbitrary angle through the body while in anatomic position. In anatomic position, the body is standing erect, with the face and toes pointing forward and the arms at the side, with the palms facing forward. Sectional images are commonly acquired and displayed according to one of the four fundamental anatomic planes that pass through the body (Fig. 1.2). The four anatomic planes are defined as follows: 1. Sagittal plane: a vertical plane that passes through the body, dividing it into right and left portions 2. Coronal plane: a vertical plane that passes through the body, dividing it into anterior (ventral) and posterior (dorsal) portions 3. Axial (transverse) plane: a horizontal plane that passes through the body, dividing it into superior and inferior portions 4. Oblique plane: a plane that passes diagonally between the axes of two other planes Medical images of sectional anatomy are, by convention, displayed in a specific orientation. Images are viewed with the right side of the image corresponding to the viewer’s left side (Fig. 1.3).

Median sagittal plane

P

Median coronal plane

A

I Sagittal A

ial Ax ne l pa

R

L

P

Oblique plane

Axial (transverse) S

r rio te al) s o rs r P do R io l) ( r te ra An ent (v

L

I Coronal

TERMINOLOGY AND LANDMARKS

FIG. 1.2  Anatomic position and planes of the body.

Directional and regional terminology is used to help describe the relative positions of specific structures within the body. Directional terms are defined in Table 1.1, and regional terms are defined in Table 1.2 and demonstrated in Fig. 1.4.

Sacrum S Liver

Lumbar vertebra

Ilium

Stomach

A

R

L

L

R

Inferior vena cava

B A P

Aorta

Spleen

A = anterior L = left P = posterior S = superior R = right I = inferior

FIG. 1.3  (A) Axial CT of abdomen. (B) 3D CT of pelvis (anterior view).

I

Femur

CHAPTER 1  Introduction to Sectional Anatomy TABLE 1.1

Directional Terminology

Direction

Definition

Superior Inferior Anterior/ventral Posterior/dorsal Medial Lateral Proximal Distal Superficial Deep Cranial/cephalic Caudal Rostral Ipsilateral Contralateral Thenar Volar

Above; at a higher level Below; at a lower level Toward the front or anterior surface of the body Toward the back or posterior surface of the body Toward the midsagittal plane Away from the midsagittal plane Toward a reference point or source within the body Away from a reference point or source within the body Near the body surface Farther into the body and away from the body surface Toward the head Toward the feet Toward the nose On the same side On the opposite side The fleshy part of the hand at the base of the thumb Pertaining to the palm of the hand or flexor surface of the wrist or the sole of the foot The front or palm of the hand The sole of the foot

Palmar Plantar

TABLE 1.2

Regional Terminology

Direction Abdominal Antebrachial Antecubital Axillary Brachial Buccal Carpal Cephalic Cervical Costal Crural Cubital Cutaneous Femoral Flank Frontal Gluteal Inguinal Lumbar Occipital Ophthalmic Otic Pectoral/mammary Pedal Pelvic Perineal Plantar Popliteal Sacral Sternal Sural Tarsal Thoracic Umbilical Vertebral

Definition Abdomen Forearm Front of elbow Armpit Upper arm Cheek Wrist Head Neck Ribs Leg Posterior surface of elbow area of the arm Skin Thigh, upper portion of leg Side of trunk adjoining the lumbar region Forehead Buttock Groin Lower back between the ribs and hips Back of the head Eye Ear Upper chest or breast Foot Pelvis Perineum Sole of foot Back of knee Sacrum Sternum Calf Ankle Chest Navel Spine

3

4

CHAPTER 1  Introduction to Sectional Anatomy

Cephalic

Ophthalmic Buccal

Frontal Otic Oral

Occipital Cervical

Sternal Brachial Antecubital Antebrachial (cubital)

Pectoral/ mammary

Axillary Thoracic

Vertebral Cubital

Costal Abdominal

Carpal

Lumbar

Flank

Sacral

Pelvic

Palmar

Gluteal (buttock)

Umbilical (navel)

Inguinal (groin)

Perineal Femoral (thigh) Crural

Tarsal

Popliteal

Sural

Cutaneous (skin)

Plantar

Pedal

FIG. 1.4  Regional terminology of the body.

External auditory meatus (EAM)

External Landmarks External landmarks of the body are helpful in identifying the location of many internal structures. The commonly used external landmarks are shown in Figs. 1.5 and 1.6.

Internal Landmarks Internal structures, in particular, vascular structures, can be located by referencing them to other identifiable regions or locations, such as organs or the skeleton (Table 1.3).

Nasion Mastoid tip

C1

Acanthion Gonion

BODY CAVITIES The body consists of two main cavities: the dorsal and ventral cavities. The dorsal cavity is located posteriorly and includes the cranial and spinal cavities. The ventral cavity, the largest body cavity, is subdivided into the thoracic and abdominopelvic cavities. The thoracic cavity is further subdivided into two lateral pleural cavities and a single, centrally located cavity called the mediastinum. The abdominopelvic cavity can be subdivided into the abdominal and pelvic cavities (Fig. 1.7). The structures located in each cavity are listed in Table 1.4.

ABDOMINAL AND PELVIC DIVISIONS The abdomen is bordered superiorly by the diaphragm and inferiorly by the pelvic inlet. The abdomen can be

C3 C5

Thyroid cartilage

C7

Vertebral prominens

Jugular notch

FIG. 1.5  External landmarks of the head and neck.

divided into four quadrants or nine regions. These divisions are useful in identifying the general location of internal organs and provide descriptive terms for the location of pain or injury in a patient’s history.

CHAPTER 1  Introduction to Sectional Anatomy TABLE 1.3 C5 and thyroid cartilage T1 T2, T3, and jugular notch T4, T5, and sternal angle

T10 and xiphoid process

Internal Landmarks

Landmark

Location

Aortic arch Aortic bifurcation Carina Carotid bifurcation Celiac trunk Circle of Willis Common iliac vein bifurcation Conus medullaris Heart—apex

2.5 cm below jugular notch L4–L5 T4–T5, sternal angle Upper border of thyroid cartilage 4 cm above transpyloric plane Suprasellar cistern Upper margin of sacroiliac joint

L3 and costal margin

Heart—base

L3, L4, and level of umbilicus L4 and crest of ilium

Inferior mesenteric artery

S1 and anterior superior iliac spine

Inferior vena cava Portal vein Renal arteries

Coccyx, symphysis pubis, and greater trochanters

5

Superior mesenteric artery Thyroid gland Vocal cords

FIG. 1.6  External landmarks of the body.

T12–L1, L2 5th intercostal space, left midclavicular line Level of 2nd and 3rd costal cartilages behind sternum 4 cm above bifurcation of abdominal aorta L5 Posterior to pancreatic neck Anterior to L1, inferior to superior mesenteric artery 2 cm above transpyloric plane Thyroid cartilage Midway between superior and inferior border of thyroid cartilage

Brain in cranial cavity Spinal cord in vertebral canal (spinal cavity)

Trachea

Mediastinum

Lung

Thoracic cavity

Thoracic cavity

Heart

Pleural cavity

Dorsal cavities

Abdominal cavity

Diaphragm Ventral cavities

Diaphragm

Spleen

Liver

Abdominal cavity

Stomach

Pancreas

Transverse colon

Small intestine

Descending colon

Ascending colon Pelvic cavity

A

B

Appendix

Pelvic cavity

FIG. 1.7  (A) Lateral view of body cavities. (B) Anterior view of body cavities.

Abdominopelvic cavity

CHAPTER 1  Introduction to Sectional Anatomy

6

TABLE 1.4

Main Body Cavities Dorsal Cranial Spinal Ventral Thoracic • Mediastinum • Pleural Abdominopelvic • Abdominal

• Pelvic

For a description of the structures located within each quadrant, see Table 1.5.

Body Cavities Contents

Regions

• Brain • Spinal cord and vertebra

The abdomen can be further divided by four planes into nine regions. The two transverse planes are the transpyloric and transtubercular planes. The transpyloric plane is found midway between the xiphisternal joint and the umbilicus, passing through the inferior border of the L1 vertebra. The transtubercular plane passes through the tubercles on the iliac crests, at the level of the L5 vertebral body. The two sagittal planes are the midclavicular lines. Each line runs inferiorly from the midpoint of the clavicle to the midinguinal point (Fig. 1.8B). The nine regions can be organized into three groups:

• Thymus, heart, great vessels, trachea, esophagus, and pericardium • Lungs, pleural membranes • Peritoneum, liver, gallbladder, pancreas, spleen, stomach, intestines, kidneys, ureters, and blood vessels • Rectum, urinary bladder, male and female reproductive system

Quadrants The midsagittal and transverse planes intersect at the umbilicus to divide the abdomen into four quadrants (Fig. 1.8A): Right upper quadrant (RUQ) Right lower quadrant (RLQ) Left upper quadrant (LUQ) Left lower quadrant (LLQ)

Superior • Right hypochondrium • Epigastrium • Left hypochondrium Middle • Right lateral • Umbilical • Left lateral Inferior • Right inguinal • Hypogastrium • Left inguinal

Right midclavicular plane

Midsagittal plane

Left midclavicular plane

Epigastrium Right hypochondrium

Left hypochondrium Transpyloric plane

RUQ

LUQ

Right lateral

Transverse plane

Hypogastrium RLQ

A

Umbilical

LLQ

Right inguinal

B FIG. 1.8  (A) Four abdominal quadrants. (B) Nine abdominal regions.

Left lateral Transtubercular plane Left inguinal

CHAPTER 1  Introduction to Sectional Anatomy TABLE 1.5

7

Organs Found Within Abdominopelvic Quadrants

Quadrant

Organs

Right upper quadrant (RUQ) Left upper quadrant (LUQ) Right lower quadrant (RLQ) Left lower quadrant (LLQ)

Right lobe of liver, gallbladder, right kidney, portions of stomach, small and large intestines Left lobe of liver, stomach, tail of the pancreas, left kidney, spleen, portions of large intestines Cecum, appendix, portions of small intestine, right ureter, right ovary, right spermatic cord Most of small intestine, portions of large intestine, left ureter, left ovary, left spermatic cord

IMAGE ACQUISITION The images displayed in this text are acquired from MRI and CT scanners. MRI uses a strong magnetic field in conjunction with nonionizing radiofrequency (RF) energy to acquire images. CT uses ionizing radiation to acquire images. Both modalities are capable of creating 2D and 3D images.

IMAGE DISPLAY Each digital image can be divided into individual regions called pixels or voxels that are then assigned a numerical value corresponding to a specific tissue property of the structure being imaged (Fig. 1.9). The numerical value of each voxel is assigned a shade of gray for image display. In CT, the numerical value (CT number) is referenced to a Hounsfield unit (HU), which represents the attenuating properties or density of each tissue. Water is used as the reference tissue and is given

a value of zero. A CT number greater than zero will represent tissue that is denser than water and will appear in progressively lighter shades of gray to white. Tissues with a negative CT number will appear in progressively darker shades of gray to black (Fig. 1.10). In magnetic resonance (MR), the gray scale represents the specific tissue relaxation properties of T1, T2, and proton density. The gray scale in MR images can vary greatly because of inherent tissue properties and can appear different with each patient and across a series of images (Fig. 1.11). The appearance of digital images can be altered to include more or fewer shades of gray by adjusting the gray scale, a process called windowing. Windowing is used to optimize visualization of specific tissues or lesions. Window width (WW) is a parameter that allows for the adjustment of the gray scale (number of shades of gray), and window level (WL) basically sets the density of the image or the center of the gray scale (Fig. 1.10).

Pixel Voxel

FIG. 1.9  Representation of a pixel and voxel.

8

CHAPTER 1  Introduction to Sectional Anatomy

Gray scale display

CT number (HU) White

256 gray shades

Black

1000 900 800 700 600 500 400 300 200 100 0 –100 –200 –300 –400 –500 –600 –700 –800 –900 –1000

Bone window

WW 2000 WL 250

Dense bone

Bone

Mediastinal Muscle Soft window Water = 0 tissue

WW 350 WL 50

Fat

Lung tissue

Air

Lung window

WW 1500 WL 500

FIG. 1.10  CT numbers and windowing on axial CT of chest.

MULTIPLANAR REFORMATION AND 3D IMAGING

Curved Planar Reformation (Reformat) (CPR)

Several postprocessing techniques can be applied to the original 2D digital data to provide additional 3D information. All current postprocessing techniques depend on creating a digital data stack from the original 2D images, thereby generating a cube of digital information (Fig. 1.12).

Images are reconstructed from data obtained along an arbitrary curved projection through the cube (Fig. 1.15).

Multiplanar Reformation (Reformat) (MPR) Images reconstructed from data obtained along any projection through the cube result in a sagittal, coronal, axial, or oblique image (see Figs. 1.13 and 1.14).

3D Imaging All 3D algorithms use the principle of ray tracing in which imaginary rays are sent out from a camera viewpoint. The data are then rotated on an arbitrary axis, and the imaginary ray is passed through the data in specific increments. Depending on the method of reconstruction, unique information is projected onto the viewing plane (Fig. 1.16).

Transverse magnetization

T1 (63% recovery to equilibrium) 90°

A

B

Lo ng T

t or Sh

Longitudinal magnetization

CHAPTER 1  Introduction to Sectional Anatomy

T2

(e .g

2 (e

., s o

.g.,

C

wat

9

D

er )

lid t issue )

TE Time T1 for solid tissue T1 for free water T1 Relaxation

T2 Relaxation

T1-weighted

T2-weighted

Proton density–weighted

FIG. 1.11  MR tissue relaxation and image contrast.

2

4 1

7

5

7

2 7

7

8

7

8

8

6

7

7

9

4

7

7

7

2

3

1 9

4

7

3

8 7 9 7 4

Sagittal plane

3

Oblique plane

7 9

8

1

5

A

6

2 7 6

7

4 5

2

5 Coronal plane

B

Axial plane

FIG. 1.12  (A) Digital cube. (B) Stack of axial image data.

CHAPTER 1  Introduction to Sectional Anatomy

10

Overview

Shaded surface display

Axial

Volume rendering

Sagittal

Coronal

MIP

FIG. 1.13  Multiplanar reformation and 3D. P

P 2

4 1 1 6 4 5

6 7

5

7

2 7

7

8

7

8

7

7

7

7

2

3

R

8 8 9 7 4

1 9

7

7 9

4

1

7

1

4

6

5 2

4

5

5

6

2

4 2

6 7

3

7

9

8

7

3

7

5

7 7

7

7

7

2

7

7

8 8

7

2

3

P 1 9

8 8 9 7 4

7

7 9

4

4

Sagittal

6

5 2

4

5

R A

1

A

Axial (transverse)

FIG. 1.14  Multiplanar reformations of brain.

R

5

7

5

7

1

7

6

2

4 2

6 7

3

7

9

8

7

3

7

2

8 8

7

7

7

7

2

7

7

3 A

Coronal

8 8 9 7 4

1 9

7

7 9

4

2 7 6

7 5

3

7

9

8

7

3

4 5

2

CHAPTER 1  Introduction to Sectional Anatomy

11

Voxels 2

4 1 1 6

6 7

5

7 7 7

2 7

7

8 8 7

8 8 9

4

7

7

7

5

2

3

4

1 9

7

7 9

4

2 7 6

7

3

7

9

8

7

3

4

MPR

5 2

5

CPR

FIG. 1.15  Image reformation. MPR, Multiplanar reformation; CPR, curved planar reformation.

Shaded Surface Display (SSD).  A ray from the

camera’s viewpoint is directed to stop at a particular user-defined threshold value. With this method, every voxel with a value greater than the selected threshold is rendered opaque, creating a surface. That value is then projected onto the viewing screen (Fig. 1.17).

Maximum Intensity Projection (MIP).  A ray from

the camera’s viewpoint is directed to stop at the voxel with the maximum signal intensity. With this method, only the brightest voxels will be mapped into the final image (Fig. 1.18).

Pix els alo ng ray Displayed pixel

FIG. 1.16  Ray tracing.

Volume Rendering (VR).  The contributions of each

voxel are summed along the course of the ray from the camera’s viewpoint. The process is repeated numerous times to determine each pixel value that will be displayed in the final image (Fig. 1.19).

S

Pix els alo ng ray

Displayed pixel I

FIG. 1.17  Shaded surface display (SSD).

12

CHAPTER 1  Introduction to Sectional Anatomy S

Projected value Maximum intensity

Pix els alo ng ray

I

FIG. 1.18  Maximum intensity projection (MIP). S

Pix els alo ng ray Displayed pixel I

FIG. 1.19  Volume rendering (VR).

REFERENCES Curry, R. A., & Tempkin, B. B. (2010). Sonography: Introduction to normal structure and functional anatomy (3rd ed.). St. Louis: Saunders. Frank, E., & Long, B. (2011). Merrill’s atlas of positioning and radiographic procedures (12th ed.). St. Louis: Mosby.

Seeram, E. (2008). Computed tomography; physical principles, clinical applications, and quality control (3rd ed.). Philadelphia: Saunders.

CHAPTER

2

Cranium and Facial Bones Gentlemen, damn the sphenoid bone! Oliver Wendell Holmes (1809–1894), Opening of anatomy lectures at Harvard Medical School

The complex anatomy of the cranium and facial bones can be intimidating. However, with three-dimensional (3D) imaging and multiple imaging planes, the task of identifying these structures can be simplified. It is important to understand the normal sectional anatomy of the cranium and facial bones to identify pathologic disorders and injuries that may occur within this area (Fig. 2.1). This chapter demonstrates the sectional anatomy of the structures listed in the outline.

FIG. 2.1  3D CT of skull.  Trauma resulting from a gunshot wound.

OBJECTIVES • Differentiate between the three cranial fossae. • Identify the location and unique structures of each cranial and facial bone. • Identify the structures of the external, middle, and inner ear, and describe their functions. • Identify the cranial sutures. • Describe the six fontanels in the infant cranium. • Describe the structures that constitute the temporomandibular joint.

• Identify the location of each paranasal sinus and the meatus into which it drains. • Identify the structures of the osteomeatal unit. • Identify the bones that form the orbit and their associated openings. • Describe the structures that constitute the globe of the eye. • List the muscles of the eye, and describe their functions and locations.

OUTLINE CRANIUM, 14 Parietal Bone, 18 Frontal Bone, 18 Ethmoid Bone, 21 Sphenoid Bone, 23 Occipital Bone, 27 Temporal Bone, 30 Structures of the External, Middle, and Inner Ear, 35 Sutures, 44 Fontanels, 47 FACIAL BONES, 49 Nasal Bones, 50

Lacrimal Bones, 50 Palatine Bones, 50 Maxillary Bones, 50 Zygomatic Bones, 53 Inferior Nasal Conchae, 56 Vomer, 56 Mandible, 57 TEMPOROMANDIBULAR JOINT, 60 Bony Anatomy, 60 Articular Disk and Ligaments, 61 Muscles, 63 Copyright © 2019, Elsevier Inc.

PARANASAL SINUSES, 66 Ethmoid, 67 Maxillary, 69 Sphenoid, 70 Frontal, 71 Osteomeatal Unit, 72 ORBIT, 73 Bony Orbit, 73 Soft Tissue Structures, 77 Optic Nerve, 79 Muscles of the Eye, 81 Lacrimal Apparatus, 84

13

14

CHAPTER 2  Cranium and Facial Bones

CRANIUM

Coronal suture

The cranium is composed of eight bones that surround and protect the brain. These bones include the parietal (2), frontal (1), ethmoid (1), sphenoid (1), occipital (1), and temporal (2) (Figs. 2.2–2.5). The cranial bones are composed of two layers of compact tissue known as the internal (inner) and external (outer) tables. Located between the two tables is cancellous tissue or spongy bone called diploe (Figs. 2.6–2.9). The base of the cranium houses three fossae called the anterior, middle, and posterior cranial fossae. The anterior cranial fossa (frontal fossa) is composed primarily of the frontal bone, ethmoid bone, and lesser wing of the sphenoid bone and contains the frontal lobes of the brain. The middle cranial fossa (temporal fossa) is formed primarily by the body of the sphenoid and temporal bones and houses the pituitary gland, hypothalamus, and temporal lobes of the brain. The posterior cranial fossa (infratentorial fossa) is formed by the occipital and temporal bones and contains the cerebellum and brainstem (Figs. 2.6 and 2.7). For additional details of the contents found within

Frontal bone Parietal bone

Supraciliary arch

Glabella

Optic canal

Sphenoid bone

Sphenoid bone (greater wing)

Superior orbital fissure Temporal bone

Optic strut

FIG. 2.2  Anterior view of skull.

Bregma

Coronal suture

Pterion Sphenoparietal suture

Frontal bone

Parietal bone

Parietomastoid suture

Sphenofrontal suture Glabella Ethmoid bone Sphenosquamosal suture

Supraorbital foramen

Sq

ua m id ou o n s e h ne p Temporal bone sutu S bo

Asterion Lambda

re

id to s as es M roc p

External auditory meatus Styloid process

FIG. 2.3  Lateral view of skull.

Lambdoidal suture Occipital bone External occipital protuberance (inion)

Occiptomastoid suture

CHAPTER 2  Cranium and Facial Bones

15

Coronal suture

S

Frontal bone

Parietal eminence

Parietal bone Superior orbital fissure

Glabella

Temporal bone

Supraciliary arch R

L

Ethmoid bone

Sphenoid bone Zygoma

Inferior nasal concha

Maxilla

Vomer

Mandible

FIG. 2.4  3D CT of anterior skull. I Parietal bone

S

Vertex

Coronal suture Frontal bone

Squamous suture Pterion Lambdoidal suture

Sphenofrontal suture

Occipital bone

Sphenoid bone Nasal bone A Ethmoid bone

P External occipital protuberance Asterion

Zygomatic arch

Parietomastoid suture

Zygoma

Occipitomastoid suture

Maxilla

Temporal bone

Mandible

Mastoid process

FIG. 2.5  3D CT of lateral skull. I

CHAPTER 2  Cranium and Facial Bones

Internal table

Diploë

External table

Ethmoid notch of frontal bone Orbital plate of frontal bone

FRONTAL BONE

Crista galli

ETHMOID BONE

Anterior cranial fossa

Cribriform plate Lesser wing of sphenoid bone

Sella turcica

SPHENOID BONE (greater wing)

Foramen rotundum

End of carotid canal

Middle cranial fossa

Foramen ovale Foramen lacerum

TEMPORAL BONE

Foramen spinosum Internal auditory canal Jugular foramen

Posterior cranial fossa

Mastoid foramen Hypoglossal canal

OCCIPITAL BONE Foramen magnum

Internal occipital protuberance

FIG. 2.6  Superior view of cranial fossae.

Ethmoid notch of frontal bone

Crista galli

A

Cribriform plate

Orbital plate of frontal bone

Middle cranial fossa

Anterior cranial fossa

Frontal bone

Sella turcica

Ethmoid bone Foramen ovale

Lesser wing of sphenoid bone

Foramen spinosum

Sphenoid bone (greater wing) Foramen lacerum

Temporal bone

Petrous portion of temporal bone Posterior cranial fossa

16

External table Occipital bone

Diploë

Clivus

P

Foramen magnum

Internal table

FIG. 2.7  3D CT of cranial fossae, superior view.

CHAPTER 2  Cranium and Facial Bones Meningeal grooves

Vertex

Sphenosquamosal suture Parietal bone

Coronal suture

External table Diploë

Sphenofrontal suture

Internal table FRONTAL BONE

Lambdoidal suture Sella turcica

Frontal sinus

Squamous suture

Crista galli SPHENOID BONE

OCCIPITAL BONE

NASAL BONE TEMPORAL BONE

ETHMOID BONE

Occipitomastoid suture Internal auditory canal

MAXILLARY BONE

Hypoglossal canal

Clivus Styloid process

VOMER

Sphenoid sinus MANDIBLE PALATINE BONE

FIG. 2.8  Lateral view of inner skull.

Frontal bone

S

Meningeal vessels

Vertex

Internal table

Diploë Crista galli External table

Frontal sinus P

A Nasal bone

Ethmoid bone

Occipital bone

Sphenoid bone Vomer Anterior clinoid process

Sella turcica

Dorsum sella

I

Internal auditory canal

External occipital protuberance

FIG. 2.9  3D CT of inner skull, lateral view.

17

CHAPTER 2  Cranium and Facial Bones

18 TABLE 2.1

by corresponding meningeal vessels and cerebral gyri and sulci (Figs. 2.8 and 2.9). The parietal bones articulate with the frontal, occipital, temporal, and sphenoid bones. The superior point between the parietal bones is the vertex, which is the highest point of the cranium (Figs. 2.9 and 2.10). Each parietal bone has a central prominent bulge on its outer surface termed the parietal eminence (Fig. 2.4). The width of the cranium can be determined by measuring the distance between the two parietal eminences.

Contents of the Cranial Fossae

Fossa

Contents

Anterior cranial fossa Middle cranial fossa

Frontal lobes of cerebrum; olfactory nerve (I) Temporal lobes of cerebrum, pituitary gland, cavernous sinus, trigeminal ganglion, internal carotid artery, hypothalamus, and the following cranial nerves: optic nerves (II) and chiasm, oculomotor (III), trochlear (IV), trigeminal (V), abducens (VI) Cerebellum, pons, medulla oblongata, midbrain, and the following cranial nerves: facial (VII), vestibulocochlear (VIII), glossopharyngeal (IX), vagus (X), accessory (XI), hypoglossal (XII)

Posterior cranial fossa

Frontal Bone The frontal bone consists of a vertical and a horizontal portion. The vertical or squamous portion forms the forehead and anterior vault of the cranium (Figs. 2.2–2.5). The vertical portion contains the frontal sinuses, which lie on either side of the midsagittal plane (Figs. 2.8, 2.9, 2.11, and 2.12). Two elevated arches, the supraciliary arches, are joined to one another by a smooth area termed the glabella (Figs. 2.2 and 2.4). The horizontal portion forms the roof over each orbit, termed the orbital plate, and the majority of the anterior cranial fossa (Figs. 2.6, 2.7 and 2.13). Located in the superior portion of each orbit is the supraorbital foramen, or notch, which exists for the passage of the supraorbital nerve (Figs. 2.2 and 2.11). Between the orbital plates is an area termed the ethmoid notch, which receives the cribriform plate of the ethmoid bone (Figs. 2.6 and 2.7).

the cranial fossa, see Table 2.1. Each cranial bone is structurally unique, and thus identification of the physical components can be challenging.

Parietal Bone The two parietal bones form a large portion of the sides of the cranium. Prominent markings and grooves that are found within the inner surface of the cranium are formed Parietal eminence Coronal suture

S

Vertex Sagittal suture

Lambdoidal suture Frontal bone

A

P

Temporal bone Asterion Occipital bone Pterion Occipitomastoid suture

Sphenofrontal suture

Squamous suture

I

Parietomastoid suture

FIG. 2.10  3D CT of lateral surface of cranium.

CHAPTER 2  Cranium and Facial Bones

Supraorbital foramen

19

Squamous portion of frontal bone

S

Frontal sinus

Nasal bone Perpendicular plate of ethmoid

Maxilla

I

FIG. 2.11  Coronal CT of frontal bone.

Frontal bone

Sella turcica

S

Dorsum sella

Frontal sinus P

A Nasal bone Ethmoid air cells

Inferior nasal concha

Hard palate

Sphenoid sinus

FIG. 2.12  Sagittal CT reformat of frontal sinus.

I

Clivus of occipital bone

Occipital bone

20

CHAPTER 2  Cranium and Facial Bones

A

Anterior clinoid process of sphenoid bone

P

Frontal sinuses

Temporal bone

FIG. 2.13  Axial CT of orbital plates.

Orbital plate of frontal bone

Occipital bone

CHAPTER 2  Cranium and Facial Bones

Ethmoid Bone The ethmoid bone is the smallest of the cranial bones and is situated in the anterior cranial fossa. This cubeshaped bone can be divided into four parts: horizontal portion, vertical portion, and two lateral masses (labyrinths) (Figs. 2.14–2.17). The horizontal portion, called the cribriform plate, fits into the ethmoid notch of the frontal bone (Figs. 2.6 and 2.7). This plate contains many foramina for the passage of olfactory nerve fibers (Figs. 2.14 and 2.15). The crista galli, a bony projection stemming from the midline of the cribriform plate,

projects superiorly to act as an attachment for the falx cerebri, which is the connective tissue that anchors the brain to the anterior cranial fossa (Figs. 2.16 and 2.17). The vertical portion of the ethmoid bone, called the perpendicular plate, projects inferiorly from the cribriform plate to form a portion of the bony nasal septum (Fig. 2.16). The lateral masses (labyrinth) incorporate thin-walled orbital plates (lamina papyracea), which create a portion of the medial orbit (Figs. 2.15 and 2.17). Contained within the lateral masses are many ethmoid air cells (ethmoid sinuses), one of the largest being the ethmoid bulla (Figs. 2.14–2.16). Projecting

Perpendicular plate Cribriform Crista galli plane Anterior ethmoid air cells Horizontal portion

Ethmoid bulla

Olfactory foramina Posterior ethmoid air cells

FIG. 2.14  Superior view of ethmoid bone.

Orbital plate of ethmoid bone (lamina papyracea)

A

Anterior ethmoid air cells Cribriform plate Zygoma Perpendicular plate of ethmoid bone

Ethmoid bulla

Posterior ethmoid air cells

Sphenoid sinus

P Dorsum sellae of sphenoid bone

21

Anterior clinoid process of sphenoid bone

FIG. 2.15  Axial CT of ethmoid bone.

22

CHAPTER 2  Cranium and Facial Bones

from the lateral masses are two scroll-shaped processes called the superior and middle nasal conchae (turbinates) and the uncinate process. Between the uncinate process and ethmoid bulla is a narrow groove called the infundibulum, which is an important landmark of the paranasal sinuses (Figs. 2.16 and 2.17).

Crista galli

The naso-orbitoethmoid (NOE) complex is the union of the ethmoid sinuses, frontal bone and sinuses, anterior cranial fossa, orbits, and nasal bones. Fractures of the NOE may cause symptoms that include nasal and forehead swelling, diplopia (double vision), and cerebrospinal fluid (CSF) rhinorrhea (leakage of CSF into the nose).

Superior nasal concha

Ethmoid air cells

Ethmoid bulla Infundibulum Uncinate process Middle nasal concha Lateral mass (labyrinth)

Perpendicular plate (vertical portion)

FIG. 2.16  Anterior view of ethmoid bone.

S

Internal table

Diploë

External table Crista galli

Orbital plate of frontal bone

Cribriform plate Orbital plate of frontal bone Orbital plate of ethmoid bone (lamina papyracea)

Infundibulum Superior nasal concha Uncinate process of ethmoid bone

Middle nasal concha

Middle nasal meatus

Bony nasal septum

Inferior nasal concha Vomer

I

FIG. 2.17  Coronal CT of ethmoid bone with crista galli.

Inferior nasal meatus

CHAPTER 2  Cranium and Facial Bones

23

termed sphenoid sinuses (Figs. 2.15 and 2.19). The anterior portion of the sella turcica is formed by the tuberculum sellae, and the posterior portion by the dorsum sellae. The dorsum sellae give rise to the posterior clinoid processes (Figs. 2.18 and 2.20–2.22). The triangularshaped lesser wings attach to the superior aspect of the body and form two sharp points called anterior clinoid processes, which, along with the posterior clinoid processes, serve as attachment sites for the tentorium cerebelli (Figs. 2.18, 2.20, and 2.22). The optic canal is completely contained within the lesser wing and provides passage of the optic nerve and ophthalmic artery

Sphenoid Bone The butterfly-shaped sphenoid bone extends completely across the floor of the middle cranial fossa (Figs. 2.6 and 2.7). This bone forms the majority of the base of the skull and articulates with the occipital, temporal, parietal, frontal, and ethmoid bones. The main parts of the sphenoid bone are the body, lesser wings (2), and greater wings (2) (Fig. 2.18). Located within the body of the sphenoid bone is a deep depression called the sella turcica, which houses the hypophysis (pituitary gland). Directly below the sella turcica are two air-filled cavities Optic groove

Greater wing

Lesser wing

Optic canal Anterior clinoid process Foramen rotundum Foramen ovale

Tuberculum sellae Body of sphenoid bone

Foramen spinosum Sella turcica

Dorsum sellae

Carotid sulcus

FIG. 2.18  Superior view of sphenoid bone.

Posterior clinoid process

Sella turcica

Dorsum sella

S

Tuberculum sella A

P

Ethmoid sinuses

Sphenoid sinus

Clivus

I

Posterior arch of C1

Occipital bone

FIG. 2.19  Sagittal CT reformat of sella turcica. Tuberculum sella Superior orbital fissure

Anterior clinoid processes Posterior clinoid process

Dorsum sellae Sella turcica (contains pituitary gland)

Greater wing Medial pterygoid plate Lateral pterygoid plate Pterygoid hamulus

Foramen rotundum

FIG. 2.20  Lateral view of sphenoid bone.

24

CHAPTER 2  Cranium and Facial Bones S Parietal bone

Posterior clinoid process

Foramen lacerum

Temporal bone L Dorsum sella

R

Condylar process of mandible

I

FIG. 2.21  Coronal CT of dorsum sella.

A Zygoma Ethmoid sinuses Superior orbital fissure

Sphenoid sinus

Sella turcica Optic canal

Greater wing of sphenoid Anterior clinoid process

Lesser wing of sphenoid

Dorsum sella Posterior clinoid processes

P

FIG. 2.22  Axial CT of anterior clinoid processes and sphenoid bone.

(Fig. 2.22). The optic canal is separated from the superior orbital fissure by a bony root termed the optic strut (inferior root) (Fig. 2.2, see bony orbit). The superior orbital fissure is a triangular-shaped opening located between the lesser and greater wings that allows for the transmission of the oculomotor, trochlear, abducens, and ophthalmic division of the trigeminal nerves, as well as the superior ophthalmic vein (Figs. 2.2, 2.22, 2.24, also see bony orbit). The greater wings extend laterally from

the sides of the body and contain three paired foramina—rotundum, ovale, and spinosum—through which nerves and blood vessels course (Figs. 2.6, 2.18, and 2.23–2.25; Table 2.2). Extending from the inferior surface of each greater wing is a pterygoid process, which is divided into medial and lateral pterygoid plates. The pterygoid plates serve as attachment sites for the pterygoid muscles used in movements of the lower jaw. The medial section is longer and has a hook-shaped

CHAPTER 2  Cranium and Facial Bones projection on its inferior end termed the pterygoid hamulus, which provides support for the gliding motion of the tendon of the tensor veli palatine muscle as it opens the eustachian tube (Figs. 2.20, 2.24, and 2.25). At the base of the pterygoid process is the pterygoid (vidian) canal, an opening for the passage of the petrosal nerve (Figs. 2.23–2.25). The pterygoid processes articulate with

25

the palatine bones and vomer to form part of the nasal cavity. The sphenoid bone is considered the keystone of the cranial bones because it is the only bone that articulates with all the other cranial bones.

Sphenoid sinus

A

Ethmoid sinuses

Pterygoid (vidian) canal

Greater wing of sphenoid bone

Foramen spinosum

Foramen ovale

Carotid canal R

L

Jugular fossa

P

FIG. 2.23  Axial CT of sphenoid bone with foramina ovale and spinosum.

Superior orbital fissure

Lesser wing

Greater wing

Body

Foramen rotundum

Pterygoid (vidian) canal Pterygoid hamulus

Lateral pterygoid plate

Medial pterygoid plate Pterygoid process

FIG. 2.24  Anterior view of sphenoid bone.

26

CHAPTER 2  Cranium and Facial Bones S Anterior clinoid process of sphenoid bone Sphenoid sinus

Greater wing of sphenoid bone

Foramen rotundum

Zygomatic arch R

L

Ramus of mandible

Pterygoid (vidian) canal

Lateral pterygoid plate

Medial pterygoid plate

Pterygoid process

I

FIG. 2.25  Coronal CT of sphenoid bone.

TABLE 2.2

Foramina and Fissures of the Skull

Bone

Foramen/Fissure

Major Structures Using Passageway

Frontal

Supraorbital foramen (or notch) Frontal foramen (or notch) Cribriform plate Foramen rotundum Foramen ovale Foramen spinosum Pterygoid canal Optic canal Superior orbital fissure

Supraorbital nerve and artery Frontal artery and nerve Olfactory nerve (I) Maxillary branch of trigeminal nerve (V2) Mandibular branch of trigeminal nerve (V3) Middle meningeal artery Petrosal nerve Optic nerve (II) and ophthalmic artery Ophthalmic vein and the following cranial nerves: oculomotor (III), trochlear (IV), ophthalmic branch of trigeminal (V1), abducens (VI) Maxillary branch of trigeminal nerve (V2) Medulla oblongata and accessory nerve (XI) Hypoglossal nerve (XII) Internal carotid artery Air in canal conducts sound to tympanic membrane Vestibulocochlear nerve (VIII) and facial nerve (VII) Facial nerve (VII)

Ethmoid Sphenoid

Sphenoid and maxillary bone Occipital Temporal

Temporal and occipital bone

Inferior orbital fissure Foramen magnum Hypoglossal canal Carotid canal External auditory meatus Internal auditory canal Stylomastoid foramen and facial nerve canal Jugular foramen

Temporal, sphenoid, and occipital bones

Foramen lacerum

Maxillary Lacrimal with maxilla Mandible

Infraorbital foramen Lacrimal groove, nasolacrimal canal Mental foramen

Internal jugular vein, glossopharyngeal nerve (IX), vagus nerve (X), and accessory nerve (XI) Fibrocartilage, internal carotid artery as it leaves carotid canal to enter cranium, nerve of pterygoid canal and a meningeal branch from the ascending pharyngeal artery Infraorbital nerve and maxillary branch of trigeminal nerve (V2) Lacrimal sac and nasolacrimal duct Mental artery and nerve

CHAPTER 2  Cranium and Facial Bones

Occipital Bone The occipital bone forms the posterior cranial fossa and the inferoposterior portion of the cranium. On the inferior portion of the occipital bone is a large oval aperture called the foramen magnum located at the junction of the brainstem and spinal cord (Fig. 2.26). The occipital bone can be divided into four portions: occipital condyles (2), basilar portion (1), and squamous portion (1) (Fig. 2.27). The occipital condyles project inferiorly to articulate with the first cervical

Pterygoid plate

27

vertebra (atlas), forming the atlantooccipital joint (Figs. 2.28 and 2.29). Located obliquely at the base of the condyles and anterolateral to the foramen magnum are the hypoglossal canals through which the hypoglossal nerve (CN XII) courses (Figs. 2.8, 2.27, 2.28, and 2.30; Table 2.2). The basilar portion forms the anterior margin of the foramen magnum and slopes superiorly and anteriorly to meet with the dorsum sella of the sphenoid bone to form the clivus (Figs. 2.8, 2.27, and 2.29–2.32). The squamous portion curves posterosuperiorly from the foramen magnum to articulate with the

Sphenoid bone Zygomatic arch Squamous portion

Clivus Temporal bone

Basilar portion (clivus)

Hypoglossal canal

Occipital condyle

Foramen magnum Occipital bone

Occipital condyles

FIG. 2.26  Inferior surface of occipital bone and cranium.

Hypoglossal canal

Foramen magnum

FIG. 2.27  Lateroinferior aspect of occipital bone.

S

Jugular fossa

Temporal bone Occipital condyle Lateral mass of C1 (atlas)

External occipital protuberance (inion)

I Dens of C2 (odontoid process)

Atlantooccipital joint

FIG. 2.28  Coronal CT reformat of occipital condyles.

28

CHAPTER 2  Cranium and Facial Bones A

Pterygoid process of sphenoid bone Maxillary sinus

Zygomatic arch Coronoid process of mandible

Ramus of mandible Styloid process of temporal bone

Occipital condyle

Atlantooccipital joint

Clivus

Foramen magnum P

FIG. 2.29  Axial CT of occipital bone at level of foramen magnum and lateral condyles.

A Ethmoid air cells Zygoma Pterygopalatine fossa

Sphenoid sinus

Zygomatic process of temporal bone

Condyle of mandible Clivus Hypoglossal canal Temporal bone

Occipital bone

Foramen magnum P

FIG. 2.30  Axial CT of occipital bone at level of clivus.

CHAPTER 2  Cranium and Facial Bones

S Dorsum sellae of sphenoid bone Internal occipital protuberance

Sella turcica of sphenoid bone A

P

Sphenoid sinus

External occipital protuberance (inion)

Clivus of occipital bone

Squamous portion of occipital bone

Anterior arch of C1

Foramen magnum Dens of C2

I

Posterior arch of C1

FIG. 2.31  Sagittal CT reformat of occipital bone. S

A

P

Pituitary gland

Squamous portion of occipital bone Sphenoid sinus

Clivus

Pons

I

Cerebellum

FIG. 2.32  Sagittal, T1-weighted MRI of occipital bone with clivus, post contrast enhancement.

29

CHAPTER 2  Cranium and Facial Bones

30

Inferior orbital fissure

A

Petro-occipital fissure Carotid canal

Foramen rotundum

Auditory (eustachian) tube

Zygomatic process

Mandibular fossa

External auditory meatus

Jugular fossa

Sigmoid sinus

P

Internal occipital protuberance

Mastoid air cells

FIG. 2.33  Axial CT of occipital bone with internal occipital protuberance.

parietal and temporal bones (Fig. 2.3). Located on the inner surface of the squama is a bony projection termed the internal occipital protuberance, which marks the site where the dural venous sinuses converge (Figs. 2.6, 2.31, and 2.33). The external occipital protuberance is a midline projection on the external surface of the squamous part of the occipital bone. The highest point of the external occipital protuberance is termed the inion (Figs. 2.27 and 2.31).

Squamous portion

External auditory meatus

Zygomatic process

Articular eminence

Temporal Bone The two temporal bones contain many complex and important structures. They form part of the sides and base of the cranium, and together with the sphenoid bone, they create the middle cranial fossa (Figs. 2.3 and 2.6). The temporal bone can be divided into four portions: squamous, tympanic, mastoid, and petrous (Figs. 2.34 and 2.35). The thin squamous portion projects upward to form part of the sidewalls of the cranium (Fig. 2.3). Extending from the squamous portion is the zygomatic process, which projects anteriorly to the zygoma of the face to form the zygomatic arch (Figs. 2.23, 2.25, 2.30, 2.34, and 2.36). At the base of the zygomatic process is the articular eminence that forms the anterior boundary of the mandibular fossa. The mandibular fossa is the depression that articulates with the condyloid process of the mandible,

Mandibular fossa Styloid process

Mastoid portion Mastoid process Tympanic portion

FIG. 2.34  Lateral view of temporal bone.

creating the temporomandibular joint (Figs. 2.34 and 2.37). The tympanic portion lies below the squama and forms the majority of the external auditory meatus (Figs. 2.33–2.35 and 2.37). Just posterior to the tympanic portion is the mastoid portion, which has a prominent conical region termed the mastoid process (Figs. 2.34 and 2.37–2.39). The mastoid process encloses the mastoid air cells and mastoid antrum. The mastoid antrum is located on the anterosuperior portion of the mastoid process. It is an air-filled cavity

CHAPTER 2  Cranium and Facial Bones

31

Tympanic portion Cochlea

Temporal bone (petrous portion)

Tympanic membrane

Head of malleus

Stapes

Tragus External auditory meatus

Cochlear nerve (CN VIII)

Incus Vestibular nerve (CN VIII)

Auricle (pinna) Facial nerve (CN VII) in facial canal

Petrous portion

Mastoid air cells

Internal auditory canal Internal auditory canal

Ampulla of superior semicircular duct

Groove for sigmoid sinus Vestibular ganglion

Jugular foramen

Posterior Superior Lateral (anterior) Semicircular canals

FIG. 2.35  Superior view of petrous portion of temporal bone with middle and inner ear.

Zygoma Zygomatic arch

Carotid canal Jugular foramen

Zygomatic process of temporal bone Styloid process Temporal bone

FIG. 2.36  Inferior surface of temporal bone and cranium.

that communicates with the middle ear (tympanic cavity) (Figs. 2.37–2.39). The petrous portion of the temporal bone is pyramidal in shape and situated at an angle between the sphenoid and occipital bones (Fig. 2.35). The posterior surface of the petrous pyramid forms the anterior bony limit of the posterior fossa (Fig. 2.6). Near the center of this surface is the

opening to the internal auditory canal, which transmits the seventh and eighth cranial nerves (Figs. 2.35 and 2.39). Other openings associated with the posterior surface of the petrous pyramid are the jugular foramen and the carotid canal, which provide passage for the internal jugular vein and the internal carotid artery (Figs. 2.36 and 2.38–2.41; Table 2.2). An enlargement of the jugular foramen is the jugular fossa (Fig. 2.42). Continuous in front of the jugular foramen is the petro-occipital fissure that separates the petrous portion of the temporal bone from the foramen magnum of the occipital bone (Fig. 2.40). The carotid canal courses superiorly at its lower segment, then changes direction and is seen coursing posterior to anterior (Figs. 2.33 and 2.38–2.41. See also Chapter 3, internal carotid arteries). Superior to the carotid canal is an indentation on the petrous portion called Meckel’s cave (Fig. 2.41). Also known as the trigeminal cistern, Meckel’s cave is located between two layers of dura and encloses the trigeminal ganglion. It is filled with CSF and is continuous with the pontine cistern and subarachnoid space (see also trigeminal nerve in Chapter 3). Between the apex of the petrous pyramid, the body of the sphenoid bone, and the basilar portion of the occipital bone is a jagged slit termed the foramen lacerum, which contains cartilage and allows the internal carotid artery to

32

CHAPTER 2  Cranium and Facial Bones

enter the cranium (Figs. 2.6 and 2.40; Table 2.2). The inferior surface of the petrous pyramid gives rise to the long slender styloid process that is attached to several muscles of the tongue and ligaments of the hyoid bone (Figs. 2.8, 2.29, and 2.34). The stylomastoid foramen is situated between the mastoid process and the styloid process. This foramen constitutes the end of the facial nerve canal (Figs. 2.38, 2.42, and 2.50–2.58; Table 2.2). The interior of the petrous pyramid houses the delicate middle and inner ear structures.

A basilar skull fracture is a fracture of the bones that form the base (floor) of the skull and typically involves the occipital, sphenoid, temporal, and/or ethmoid bones. Basilar skull fractures can cause tears in the meninges, the membranes surrounding the brain. Subsequent leakage of CSF into the nasopharynx may cause the patient to experience a salty taste. Other clinical signs of a basilar skull fracture may include bruising behind the ears or around the eyes; loss of hearing, smell, or vision; and possible nerve damage resulting in weakness of the face.

Mandibular fossa

S

Mastoid antrum

Articular eminence A

P

Mastoid air cells in mastoid process

I

Mandibular condyle

External auditory meatus

FIG. 2.37  Sagittal CT reformat of temporal bone.

Mastoid antrum

Tympanic cavity (middle ear) Stylus in facial canal Carotid canal

Mastoid process Bony part of eustachian tube Stylus in stylomastoid foramen

FIG. 2.38  Coronal view of temporal bone.

Mastoid air cells

CHAPTER 2  Cranium and Facial Bones

Malleus

33

Sphenoid sinus

A

Carotid canal

Mastoid air cells

Mastoid antrum

Vestibule

P

Internal auditory canal

FIG. 2.39  Axial CT of temporal bone with internal auditory canal (IAC).

A Nasolacrimal duct

Pterygoid process

Pterygomaxillary fissure

Zygomatic arch

Clivus

Foramen ovale

Eustachian (auditory) tube

Foramen spinosum

Mandibular condyle

Foramen lacerum R

L External auditory meatus

Carotid canal Petrooccipital fissure

Mastoid air cells

Jugular foramen

Internal occipital protuberance

Occipital bone P

FIG. 2.40  Axial CT of temporal bone with foramen lacerum, jugular foramen, and carotid canal.

34

CHAPTER 2  Cranium and Facial Bones

Posterior clinoid process Temporal bone

Sphenoid sinus

Meckel’s cave

Condylar process of mandible

Sphenoid bone

Carotid canal

FIG. 2.41  Coronal CT reformat of temporal bone with Meckel’s cave.

S Semicircular canals of inner ear

Jugular fossa

Facial nerve canal

Mastoid air cells

Mastoid process

Hypoglossal canal

Stylomastoid foramen

Occipital condyle

I

FIG. 2.42  Coronal CT reformat of stylomastoid foramen.

CHAPTER 2  Cranium and Facial Bones

Structures of the External, Middle, and Inner Ear The structures of the ear can be divided into three main portions: external, middle, and inner (Figs. 2.43–2.59). The external ear consists of the auricle and the external auditory meatus. The external auditory meatus is a External ear

Middle ear

35

sound-conducting canal that terminates at the tympanic membrane of the middle ear (Figs. 2.40 and 2.43). The narrow, air-filled middle ear, or tympanic cavity, communicates with both the mastoid antrum and the nasopharynx. Air is conveyed from the nasopharynx to the tympanic cavity through the eustachian tube (auditory tube) (Figs. 2.40 and 2.43). The middle ear consists of the Inner ear Semicircular canals

Malleus

Oval window

Auricle (pinna)

Posterior Superior (anterior) Temporal bone (petrous portion)

Lateral

Scutum

tympan Tegman i

Vestibular complex Cochlea Internal auditory canal Vestibulocochlear nerve (cranial nerve VIII) Bony labyrinth of inner ear

Cartilage

Stapes

Tympanic membrane

External auditory meatus

Incus

A

Round Internal window jugular vein

Eustachian (auditory) tube To pharynx

Incus

Epitympanum

Prussak space

Stapes footplate/oval window

Scutum Malleus

Mesotympanum

Tympanic membrane

Hypotympanum Eustachian tube

B

FIG. 2.43  (A) Orientation of the external, middle, and inner ear in coronal view. (B) Coronal view of auditory ossicles and tympanic cavity. Superior (anterior) semicircular canal Cochlea

Vestibule

Posterior semicircular canal

Oval window

Round window

Lateral semicircular canal

Basilar turn of cochlea

FIG. 2.44  Bony labyrinth.

36

CHAPTER 2  Cranium and Facial Bones

Clivus

A

Cerebellopontine angle cistern

Cochlea

CN VII

Vestibule CN VIII R

L Semicircular canal

Internal auditory canal

P

FIG. 2.45  Axial, T2-weighted MRI of inner ear.

A

Cochlea Inner ear

Middle ear R

L

External auditory meatus Vestibule Semicircular canal

P

FIG. 2.46  Axial CT of temporal bone at level of external auditory meatus.

CHAPTER 2  Cranium and Facial Bones Ampulla Superior semicircular canal and duct Dura mater

Posterior semicircular canal and duct

Endolymphatic sac Endolymphatic duct in vestibular aqueduct Utricle

Lateral semicircular canal and duct

Saccule

Otic capsule Stapes in oval window

Scala vestibuli

Incus

Cochlear duct Scala tympani

Malleus Tympanic cavity External auditory meatus

Tympanic membrane

Cochlear aqueduct Vestibule

Round window

Otic capsule

Eustachian (auditory) tube

FIG. 2.47  Membranous labyrinth.

Pons

A

Endolymphatic sac

Cochlea Semicircular canal

R

L Fourth ventricle

Cerebellum

P

FIG. 2.48  Axial, T2-weighted MRI with enlarged endolymphatic sac.

37

38

CHAPTER 2  Cranium and Facial Bones Squamous portion of temporal bone

A

R

L

Mastoid air cells

Occipitomastoid suture

Sigmoid sinus

P

Superior semicircular canal

Petrous portion of temporal bone

FIG. 2.49  Axial CT of superior semicircular canal.

tympanic membrane and three auditory ossicles (malleus, incus, and stapes) (Fig. 2.43B). The tympanic membrane transmits sound vibrations to the auditory ossicles. The auditory ossicles, which are suspended in the middle ear, conduct sound vibrations from the tympanic membrane to the oval window of the inner ear (Figs. 2.43, 2.49–2.59). The middle ear can be subdivided into the epitympanum, mesotympanum, and hypotympanum. The epitympanum, also called the attic, is located superior to the tympanic membrane and contains the head of the malleus and body of the incus. It communicates with the mastoid air cells through a narrow opening called the aditus ad antrum (mastoideum), a potential route for the spread of infection from the middle ear to the mastoid air cells (Figs. 2.50 and 2.51). The roof of the epitympanum is separated from the middle cranial fossa by a thin layer of bone termed the tegmen tympani. Two other important landmarks of the epitympanum include the scutum and the Prussak space. The scutum is a sharp, bony spur on the lateral wall of the tympanic cavity and the superior wall of the external auditory meatus (Figs. 2.43B and 2.57). The scutum provides the superior attachment site for the tympanic membrane. The Prussak space (lateral

epitympanic recess) is bordered laterally by the tympanic membrane, superiorly by the scutum, medially by the neck of the malleus, and inferiorly by the lateral process of the malleus (Figs. 2.43 and 2.57). The boundaries of the Prussak space limit the spread of infection to other compartments of the middle ear. The mesotympanum is the portion of the middle ear that is medial to the tympanic membrane and contains the stapes, the long process of the incus, the handle of the malleus, and the oval and round windows (Figs. 2.43B and 2.56). The hypotympanum is the portion of the middle ear that is located inferior to the lower border of the tympanic membrane and is the site of the tympanic opening for the eustachian tube (Figs. 2.43B and 2.49–2.59). The inner ear, or bony labyrinth, contains the vestibule and semicircular canals, which control equilibrium and balance, and the cochlea, which is responsible for hearing (Figs. 2.43–2.48). The vestibule is a small bony compartment located between the semicircular canals and the cochlea. Two openings of the vestibule are the oval window (Fig. 2.44) for the footplate of the stapes and the vestibular aqueduct, which contains the endolymphatic duct (Fig. 2.47). The semicircular canals are

CHAPTER 2  Cranium and Facial Bones continuous with the vestibule and are easily identified because of their three separate passages (superior [anterior], posterior, and lateral) that are at right angles to each other (Figs. 2.42–2.44). The three interconnected semicircular canals are lined with microscopic hairs called cilia and are filled with fluid known as endolymph. Every time the position of the head changes, the

Epitympanum

fluid moves against the cilia, creating a kind of motion sensor. This helps the brain create a sense of balance. The cochlea is a spiral-shaped structure with a base that lies on the internal auditory canal (Figs. 2.43 and 2.45). Located within the basilar turn of the cochlea is the round window, which allows the fluid of the inner ear to move slightly for propagation of sound waves and nerve

Malleus

A

Facial nerve (CN VII) canal (labyrinthine segment)

Prussak space Aditus ad antrum mastoideum

R

L Internal auditory canal (IAC)

Mastoid antrum

Lateral semicircular canal

P

Posterior semicircular canal

Vestibule

FIG. 2.50  Axial CT of lateral semicircular canal.

A

Malleus Facial nerve canal (tympanic segment)

Prussak space Incus

Cochlea (first turn) R

L Internal auditory canal (IAC)

Aditus ad antrum mastoideum Mastoid antrum

Lateral semicircular canal

P

39

Vestibule

FIG. 2.51  Axial CT of malleus and incus.

40

CHAPTER 2  Cranium and Facial Bones

impulses to be sent to the brain (Figs. 2.44 and 2.47). Within the bony labyrinth is a complicated system of ducts called the membranous labyrinth, which is filled with endolymph, a fluid that helps with the propagation of sound waves (Fig. 2.47). Extending from the vestibule is a slender endolymphatic duct that terminates as the endolymphatic sac, which is located between two dural

layers on the posterior wall of the petrous pyramid (Figs. 2.47 and 2.48). The endolymphatic duct and sac are thought to be responsible for the reabsorption of endolymph and may contribute to vestibular dysfunction. Figs. 2.49–2.59 provide sequential computed tomography (CT) images through the external, middle, and inner ear in the axial and coronal planes, respectively. (Text continues on page 44)

Malleus

Stapes

A

Cochlea

Incus

R

L Internal auditory canal (IAC)

Facial nerve canal (mastoid segment) Oval window

P

Posterior semicircular canal

FIG. 2.52  Axial CT of auditory ossicles.

A

Tensor tympani muscle Eustachian tube

Malleus

Carotid canal R

L Cochlea (basal turn)

External auditory meatus (EAM) Facial nerve canal (mastoid segment)

FIG. 2.53  Axial CT of cochlea.

P

Round window

CHAPTER 2  Cranium and Facial Bones A

Tympanic membrane

Condyloid process of mandible (condyle)

Hypotympanum

External auditory meatus (EAM)

R

L Jugular foramen

Mastoid air cells

P

Occipital bone

Facial nerve canal (mastoid segment)

FIG. 2.54  Axial CT of tympanic membrane.

S

Mastoid antrum

Lateral semicircular canal

Posterior semicircular canal Facial nerve canal (mastoid segment) Stylomastoid foramen

R

L Occipital condyle Hypoglossal canal

C1

Mastoid tip

I

Jugular foramen

FIG. 2.55  Coronal CT reformat of semicircular canals.

41

CHAPTER 2  Cranium and Facial Bones

42

Mastoid antrum

S

Lateral semicircular canal

Vestibule Internal auditory canal (IAC) Round window

Facial nerve canal (tympanic segment) L

R External auditory meatus (EAM)

Mesotympanum

I

FIG. 2.56  Coronal CT reformat of vestibule. Squamous portion of temporal bone

Epitympanum

S

Incus

Superior semicircular canal

Oval window Internal auditory canal (IAC) Basal turn of cochlea

Prussak space R

L

Scutum

Hypotympanum

External auditory meatus (EAM)

Facial Stapes nerve canal (tympanic segment)

I

Tympanic membrane

Tympanic annulus

FIG. 2.57  Coronal CT reformat of IAC.

CHAPTER 2  Cranium and Facial Bones Tegmen tympani

Incus

S

43

Neck of malleus Facial nerve canal (tympanic segment)

Facial nerve canal (labyrinthine segment)

R

L

External auditory meatus (EAM)

Malleus

I

Cochlea

Carotid canal

FIG. 2.58  Coronal CT reformat of EAM. Tegmen tympani

Malleus Geniculate ganglion of facial nerve head

S

Mesotympanum First turn of cochlea L

R Epitympanum External auditory meatus

Anterior scutum

Tympanic Hypotympanum membrane

I

FIG. 2.59  Coronal CT reformat of cochlea.

Second turn of cochlea

Carotid canal

44

CHAPTER 2  Cranium and Facial Bones

Meniere disease is a disorder of the membranous labyrinth that results from a failure of the mechanism controlling the production and elimination of endolymph. In advanced cases, there is an increased accumulation of endolymph volume, resulting in an abnormal distention of the membranous labyrinth (endolymphatic hydrops). Meniere disease is most common in middle age and may become bilateral in up to 50% of affected patients. Symptoms include episodic vertigo accompanied by nausea, fluctuating hearing loss, and a feeling of fullness in the affected ears. The success of surgical intervention in relieving Meniere disease depends a great deal on the ability to image and evaluate the vestibular aqueduct and endolymphatic duct and sac. Cholesteatomas are epidermoid cysts of the middle ear that can be acquired or congenital. The lumen of the cyst is filled with debris. As a cholesteatoma enlarges, it destroys the ossicles and adjacent bony structures. Cholesteatomas are usually associated with chronic infection, aural discharge, and conductive or mixed deafness. The Prussak space is the most common site of acquired cholesteatomas within the tympanic cavity.

Sutures The cranial bones are joined by four main articulations termed sutures. The squamous suture, which is located on the side of the cranium, joins the squamous portion of the temporal bone to the parietal bone. The coronal Coronal suture

Sphenoparietal suture

suture runs across the top of the cranium and is the articulation between the frontal and parietal bones. The sagittal suture provides the articulation between the parietal bones along the midsagittal plane. The lambdoidal suture is located posterior in the cranium and joins the occipital and parietal bones (Figs. 2.3 and 2.60–2.63). Sutures corresponding to the mastoid portion of the temporal bone include the occipitomastoid suture between the occipital bone and mastoid portion of the temporal bone and the parietomastoid suture between the parietal bone and mastoid portion of the temporal bone. The asterion is a point on the skull corresponding to the posterior end of the parietomastoid suture (Figs. 2.3 and 2.60). Sutures corresponding to the sphenoid bone include the sphenosquamosal suture between the sphenoid bone and squamous portion of the temporal bone, the sphenofrontal suture between the greater wing of the sphenoid bone and the frontal bone, and the sphenoparietal suture located between the greater wing of the sphenoid bone and the parietal bone. The region surrounding the sphenoparietal suture where the parietal, sphenoid, temporal, and frontal bones meet is termed the pterion, an important landmark because it is considered the weakest part of the skull and is also the site of the anterolateral (sphenoid) fontanel in neonates (Figs. 2.3 and 2.60). The frontal (metopic) suture divides the frontal bone into halves as it extends from the anterior fontanel or sagittal suture to the nasion in infants and children and typically disappears by the age of 6 (Fig. 2.64).

Temporal bone

Vertex

Sagittal suture

Parietal bone

Frontal bone

Sphenofrontal suture

Lambdoidal suture Pterion Occipital bone Sphenosquamosal suture

Squamous Parietomastoid suture suture

Occipitomastoid suture

FIG. 2.60  3D CT of lateral surface of cranium.

Asterion

CHAPTER 2  Cranium and Facial Bones A

Sphenoid bone

Sphenosquamosal suture Temporal bone R

L

Mastoid process

Clivus

Foramen magnum

Occipital bone

P

Occipitomastoid suture

FIG. 2.61  Axial CT of occipitomastoid suture. A

Frontal bone

Squamous suture Temporal bone L

R Petrous portion of temporal bone

Mastoid air cells

P Internal occipital protuberance

Occipital bone

Lambdoidal suture

FIG. 2.62  Axial CT of lambdoidal suture.

45

CHAPTER 2  Cranium and Facial Bones

46

A

Frontal bone

Coronal suture

L

R

Squamous suture

Squamous portion of temporal bone

Occipital bone

P Lambdoidal suture

FIG. 2.63  Axial CT of coronal suture.

The sutures in neonates are not fully closed, allowing for growth of the head after birth. Craniosynostosis, which is the result of premature ossification of one or more of the cranial sutures, causes abnormal growth of the cranium and can limit the growth of the brain.

The pterion is known as the weakest part of the skull and is located over the anterior division of the middle meningeal artery. A severe blow to the side of the head causing a fracture and rupture of the middle meningeal artery may result in an epidural hematoma. A favored site of access for performing a bur hole to drain the hematoma is at the pterion.

CHAPTER 2  Cranium and Facial Bones

Fontanels Within the neonatal cranium are six areas of incomplete ossification called fontanels. The largest is the anterior fontanel located at the junction of the upper parietal and frontal bones termed the bregma (Fig. 2.64). This fontanel remains open until the age of 2. Located at the lambda, the junction of the parietal and occipital bones is the posterior fontanel (Fig. 2.65). The posterior fontanel typically closes between the first and third months after birth. On the sides of the cranium are four additional fontanels, two anterolateral (sphenoid) and two posterolateral (mastoid) (Figs. 2.65 and 2.66). The

Anterior fontanel (bregma)

S

anterolateral fontanels are located between the parietal and greater wing of the sphenoid bones. The posterolateral fontanels are located at the junction of the occipital, temporal, and parietal bones. The anterior and posterolateral fontanels ossify at approximately 2 years of age, whereas the posterior and anterolateral fontanels close between 1 and 3 months after birth.

Bulging of the anterior fontanel may indicate increased intracranial pressure, whereas a sunken fontanel may indicate dehydration.

Sagittal suture

Coronal suture R

L

Frontal (metopic suture)

47

I

FIG. 2.64  3D CT of infant cranium, anterior view.

CHAPTER 2  Cranium and Facial Bones Anterolateral fontanel S Coronal suture (sphenoid)

Parietal bone Fro n bon tal e

48

Posterior fontanel (lambda)

A

P Lambdoidal suture Posterolateral fontanel (mastoid)

Temporal bone

Occipitomastoid suture

Sphenoid bone

Sphenosquamosal suture

I

Squamous suture

Occipital bone

FIG. 2.65  3D CT of 17-week-old infant cranium, lateral view.

Anterior fontanel (bregma)

Sagittal suture

Coronal suture

Parietal bone

Frontal bone

al por Tem one b

Frontal (metopic) suture

Nasion

Sphenoid bone

Anterolateral fontanel (sphenoid)

FIG. 2.66  3D CT of 17-week-old infant cranium, oblique view.

CHAPTER 2  Cranium and Facial Bones

49

FACIAL BONES The face is made up of 14 facial bones. The facial bones can be difficult to differentiate because of their relatively small size and irregular shape. They consist of the nasal

(2), lacrimal (2), palatine (2), maxilla (2), zygoma (2), inferior nasal conchae (2), vomer (1), and mandible (1) (Figs. 2.67–2.85).

Frontal bone

Frontal process of maxilla Nasal bones

Superior orbital fissure

Lacrimal bone

Zygoma

Bony nasal septum

Ethmoid bone

Inferior orbital fissure Perpendicular plate of ethmoid

Zygomatic process of maxilla Maxilla

Vomer

Infraorbital foramen Inferior nasal concha

Alveolar process of maxilla

Anterior nasal spine (acanthion) Mandible

Alveolar process of mandible

FIG. 2.67  Anterior view of facial

bones.

Mental protuberance

l nta Fro ne bo Parietal bone

Lacrimal bone

Ethmoid bone

l sa Naone b

id eno Sph one b

Lacrimal groove Anterior nasal spine (acanthion) Temporal process of zygoma

Zygoma

Zygomatic arch Occipital bone

Maxilla

Zygomatic process of temporal bone

Alveolar process

External auditory meatus Mandible

Mandibular condyle Angle (gonion)

Mental foramen

Coronoid process

Mandibular notch

FIG. 2.68  Sagittal view of facial

bones.

50

CHAPTER 2  Cranium and Facial Bones Hard palate Horizontal portion of palatine bone

Palatine process of maxilla

Zygoma

A

Temporal process of zygoma

Zygomatic arch R

L Zygomatic process of the temporal bone

Pterygoid process of sphenoid bone

Temporal bone

Condyloid process of mandible

Mastoid process

Clivus of occipital bone

P

C1

Occipital bone

FIG. 2.69  3D CT of inferior surface of cranial bones with mandible disarticulated.

Nasal Bones The two nasal bones form the bony bridge of the nose and articulate with four bones: the frontal and ethmoid bones of the cranium and the opposite nasal bone and maxilla (Figs. 2.67, 2.68, 2.70, 2.71, and 2.73).

Lacrimal Bones Posterior to the nasal bones and maxilla are the lacrimal bones, which are situated on the medial wall of each orbit (Fig. 2.70). The junction between the lacrimal bones and the maxillae forms the lacrimal groove, which accommodates the lacrimal sacs that are part of the drainage route for excess lacrimal fluid (tears) (Figs. 2.67, 2.68, 2.70, and 2.71).

Palatine Bones The palatine bones are slightly L-shaped and are located in the posterior aspect of the nasal cavity between the maxilla and the pterygoid process of the sphenoid bone

(Fig. 2.70). The palatine bones consist of a horizontal portion and a vertical portion. The horizontal portion of the palatine bones joins anteriorly with the palatine process of the maxilla to form the hard palate (Figs. 2.8, 2.69, 2.74, and 2.75). The vertical portion extends to form a segment of the lateral wall of the nasal cavity and the medial wall of the orbit (Fig. 2.70). The pterygopalatine fossa is a gap between the pterygoid process of the sphenoid bone, maxilla, and palatine bones. The pterygopalatine fossa contains the maxillary nerve V2 (second division of the trigeminal nerve), the pterygopalatine ganglion, and the third part of the maxillary artery (Figs. 2.30, 2.70, and 2.77).

Maxillary Bones The largest immovable facial bones are the maxillary bones, which fuse at the midline to form a pointed process termed the anterior nasal spine (Figs. 2.68, 2.70, and 2.71). An opening on the anterior aspect of the maxilla is the infraorbital foramen, which transmits the infraorbital

CHAPTER 2  Cranium and Facial Bones S Orbital plate of ethmoid bone

Frontal sinus Orbital plate of frontal bone

Optic canal Palatine bone (vertical portion)

Nasal bone Lacrimal bone

Sphenoid bone

Lacrimal groove Frontal process of maxilla Uncinate process of ethmoid bone

Sella turcica of sphenoid bone P

A

Foramen rotundum

Infraorbital canal

Pterygopalatine fossa

Inferior nasal concha Anterior nasal spine

Palatine bone (vertical portion)

Maxillary sinus Alveolar process of maxilla

Pterygoid plate of sphenoid bone I

FIG. 2.70  Sagittal view of orbit and facial bones.

Temporal process of zygoma

Frontal bone

Lacrimal bone

Lacrimal groove

Temporal bone

Nasal bone

Zygomatic process of temporal bone

Frontal process of maxilla

Zygomatic arch

Maxilla

Anterior nasal spine

Ramus of mandible

Alveolar process of maxilla

Zygoma

Zygomatic process of maxilla

Maxillary sinus

Mental foramen

Mandible

FIG. 2.71  3D CT of oblique aspect of facial bones.

51

CHAPTER 2  Cranium and Facial Bones

52

S

Frontal bone Crista galli

Perpendicular plate of ethmoid

Middle nasal concha

Infraorbital foramen

Zygoma

Maxillary sinus

Middle nasal meatus

Inferior nasal concha

Zygomatic process of maxilla

Vomer Alveolar process of maxilla

Maxilla

Inferior nasal meatus

Palatine process of maxilla

I

FIG. 2.72  Coronal CT of maxilla and zygoma.

S

Frontal bone Frontal sinus Nasal bone Perpendicular plate of ethmoid bone

Frontal process of maxilla I

FIG. 2.73  Coronal CT of nasal bones.

CHAPTER 2  Cranium and Facial Bones Zygoma

Palatine process of maxilla Horizontal portion of palatine bone Zygomatic arch

53

form the alveolar process, which accepts the roots of the teeth (Figs. 2.67, 2.71, 2.75, and 2.76). The palatine process of the maxilla extends posteriorly to form threefourths of the hard palate. The posterior one-fourth of the hard palate is created by the horizontal portion of the palatine bones (Figs. 2.69, 2.74 and 2.75).

Zygomatic Bones Temporal bone Foramen magnum Occipital bone

FIG. 2.74  Inferior view of facial bones and hard palate.

nerve and blood vessels (Figs. 2.67 and 2.72). The maxillary bones contain the large maxillary sinuses and four processes: the frontal process, zygomatic process, alveolar process, and palatine process (Figs. 2.67 and 2.72– 2.76). The frontal and zygomatic processes project to articulate with the frontal bones of the cranium and the zygomatic bones of the face (Figs. 2.71–2.73). The inferior border of the maxilla has several depressions that

A

The zygomatic bones (zygoma or malar) create the prominence of the cheek and contribute to the lateral portion of the bony orbit (Figs. 2.67, 2.71, 2.72, 2.77, and 2.78). They articulate with the maxilla and temporal, frontal, and sphenoid bones. The temporal process of the zygomatic bone extends posteriorly to join the zygomatic process of the temporal bone to form the zygomatic arch (Figs. 2.68, 2.69, 2.71, 2.74, and 2.77). Le Fort fractures are a result of direct anterior facial injuries. They are classified into three groups according to the facial bones that are traumatized. Type I: The alveolar process of the maxilla and the hard palate are separated from the superior part of the skull. Type II: The alveolar, zygomatic, and frontal processes of the maxilla along with the nasal bones are separated from the frontal and zygomatic bones. Type III: Virtually the entire facial skeleton, including the maxillae, nasal bones, and zygomatic bones, is separated from the frontal bone above it.

Palatine process of Alveolar process maxilla (hard palate) of maxilla

Pterygoid process of sphenoid bone

Horizontal portion of palatine bone (hard palate)

R

L

P

Styloid process of temporal bone

Mandible

FIG. 2.75  Axial CT of hard palate.

CHAPTER 2  Cranium and Facial Bones

54

A

Alveolar process of maxilla

R

L

Ramus of mandible

Pterygoid process of sphenoid bone

P

FIG. 2.76  Axial CT of alveolar process of maxilla.

Inferior nasal concha

Nasolacrimal duct Maxilla A

Zygomatic process of maxilla

Maxillary sinus

Zygoma Temporal process of zygoma Zygomatic arch

Pterygoid process of sphenoid bone

Pterygomaxillary fissure Pterygopalatine fossa Mandibular condyle Occipital bone Nasal septum

P

Foramen magnum of occipital bone

FIG. 2.77  Axial CT of facial bones.

CHAPTER 2  Cranium and Facial Bones

A

Nasal bone Frontal process of maxilla

Lacrimal bone

Anterior ethmoid sinuses

Zygoma

Greater wing of sphenoid bone

Posterior ethmoid sinuses Sphenoid sinus

P

Dorsum sella of sphenoid bone

FIG. 2.78  Axial CT of facial bones and ethmoid sinuses.

55

56

CHAPTER 2  Cranium and Facial Bones

Inferior Nasal Conchae

Vomer

The inferior nasal conchae (inferior nasal turbinates) arise from the maxillary bones and project horizontally into the nasal cavity (Figs. 2.67, 2.72, and 2.77). They can be identified by their scroll-like appearance. These conchae in conjunction with the superior and middle nasal conchae of the ethmoid bone divide the nasal cavity into three openings or meati, termed superior, middle, and inferior (Figs. 2.72, 2.79, and 2.80).

The vomer is an unpaired facial bone located on the midsagittal line. The vomer forms the inferior portion of the bony nasal septum as it projects superiorly to articulate with the perpendicular plate of the ethmoid bone (Figs. 2.8, 2.9, 2.67, and 2.72).

Superior nasal concha Superior nasal meatus

Frontal sinus Sphenoid sinus

Middle nasal concha

Opening for eustachian tube

Middle nasal meatus

Inferior nasal concha

Inferior nasal meatus

FIG. 2.79  Sagittal view of nasal meatus. Anterior ethmoid air cell

Posterior ethmoid air cell

S

Sphenoethmoidal recess

Sella turcica

Frontal sinus

Superior nasal meatus

P Sphenoid sinus

A Middle nasal concha

Basal lamella of middle concha (turbinate) Nasopharynx Middle nasal meatus

Inferior nasal meatus

I

FIG. 2.80  Sagittal CT reformat of nasal meatus.

Inferior nasal concha

CHAPTER 2  Cranium and Facial Bones

vertical portion of the mandible is called the ramus (Figs. 2.71 and 2.81–2.83). Each ramus has two processes at its superior portion: the coronoid process, anteriorly, and the condyloid process (condyle), posteriorly (Figs. 2.81, 2.82, 2.84, and 2.85). They are separated by a concave surface called the mandibular notch. The coronoid process serves as an attachment site for the temporalis and masseter muscles, whereas the condyloid process articulates with the mandibular fossa of the temporal bone to form the temporomandibular joint (TMJ) (Figs. 2.82 and 2.86).

Mandible The largest facial bone is the mandible. This bone is composed primarily of horizontal and vertical portions (Figs. 2.81 and 2.82). The angle created by the junction of these two portions is termed the gonion. The curved horizontal portion, called the body, contains an alveolar process (similar to the maxilla) that receives the roots of the teeth of the lower jaw. The mental foramina extend through the body of the mandible and allow passage of the mental artery and nerve (Figs. 2.81 and 2.82). The

Coronoid process

Neck Condyloid process

Alveolar portion Mandibular notch Symphysis

Ramus

Mental protuberance

Angle (gonion)

Mental foramen

Body

FIG. 2.81  Lateral view of mandible.

Zygomatic arch S

Mandibular notch

Mandibular fossa of temporal bone

Zygoma

External auditory meatus

Coronoid process of mandible

Condyloid process of mandible (condyle) A

P

Alveolar process of mandible

Ramus of mandible Angle of mandible (gonion)

Mental foramen

57

I

Body of mandible

FIG. 2.82  3D CT of lateral aspect of mandible.

CHAPTER 2  Cranium and Facial Bones

58

Anterior clinoid process

S

Greater wing of sphenoid bone

Sphenoid sinus

Pterygoid process of sphenoid bone (lateral plate)

Foramen rotundum

I Pterygoid hamulus of sphenoid bone

Ramus of mandible

Zygomatic arch

FIG. 2.83  Coronal CT of mandibular rami.

A

Maxillary sinus

Zygoma Coronoid process of mandible

Mandibular notch

Mandibular ramus

Condyloid process of mandible (condyle) Occipital condyle

Foramen magnum P

FIG. 2.84  Axial CT of mandibular rami.

CHAPTER 2  Cranium and Facial Bones

A Zygoma

Zygomatic process of temporal bone Condyloid process of mandible (condyle)

Clivus Hypoglossal canal

Foramen magnum P

FIG. 2.85  Axial CT of mandibular condyles.

59

60

CHAPTER 2  Cranium and Facial Bones

TEMPOROMANDIBULAR JOINT The TMJ is a modified hinge joint that allows for the necessary motions of mastication.

condyloid process of the mandible (condyle). The articular eminence creates the anterior boundary of the joint, preventing the forward displacement of the mandibular condyle (Figs. 2.86 and 2.87).

Bony Anatomy The mandibular fossa and articular eminence of the temporal bone form the superior articulating surface for the Articular Articular disk Posterior eminence (meniscus) band

Mandibular fossa

Anterior band

FIG. 2.86  Lateral view of temporomandibular joint.

Lateral pterygoid muscle

Mandibular fossa

Condyloid process of mandible (condyle)

S

External auditory meatus

Articular eminence A

P

Condyloid process of mandible (condyle)

I

Mastoid air cells

FIG. 2.87  Sagittal CT reformat of temporomandibular joint.

CHAPTER 2  Cranium and Facial Bones

articular disk is not tightly bound to the fossa but moves anteriorly with the condyle. Several ligaments help maintain the position of the articular disk. The articular disk is attached to the medial and lateral surfaces of the condyle by the collateral ligaments (Figs. 2.89 and 2.90). Lateral stability is provided by the temporomandibular ligament (lateral ligament), which extends from the articular eminence and zygomatic process to the posterior aspect of the articular disk and the condylar head and neck (Fig. 2.91). Additionally, this ligament restricts the posterior movement of the condyle and articular disk.

Articular Disk and Ligaments The articular disk, frequently called the meniscus, is shaped like a bowtie and is interposed between the mandibular condyle and fossa to act as a shock absorber during jaw movement (Figs. 2.86, 2.88, and 2.89). The anterior and posterior portions of the meniscus are referred to as the anterior and posterior bands, respectively. The anterior band attaches to the lateral pterygoid muscle, and the posterior band has fibrous connections to both the temporal bone and the posterior aspect of the condyle (Figs. 2.86 and 2.88). The

S

Mandibular fossa

External auditory meatus

Articular eminence

Condyloid process

Articular disk

I A, closed

S

Articular disk

Posterior band

Condyloid process

Anterior band

61

P

I B, open

FIG. 2.88  Sagittal, T1-weighted MRI of temporomandibular joint and articular disk.  (A) Closed. (B) Open.

62

CHAPTER 2  Cranium and Facial Bones Articular disk (meniscus)

Mandibular fossa

Fibrous capsule

Joint capsule

Lateral collateral ligament Medial collateral ligament

Condyloid process

Joint capsule

FIG. 2.89  Coronal view of temporomandibular joint and collateral ligaments.

S

Mandibular fossa Articular disk Condyloid process Medial collateral ligament Lateral collateral ligament

L

R

I

FIG. 2.90  Coronal, T1-weighted MRI of temporomandibular joint.

CHAPTER 2  Cranium and Facial Bones Zygomatic process

Fibrous capsule

63

Temporal bone

Styloid process Temporomandibular (lateral) ligament

Stylomandibular ligament

Angle of mandible

FIG. 2.91  Sagittal view of temporomandibular joint and lateral ligament.

Muscles The cooperative actions of four muscles located on each side of the TMJ provide the movement of the mandible and are collectively referred to as the muscles of mastication (Fig. 2.92). The fan-shaped temporalis muscle originates on the temporal fossa, inserts on the coronoid process and anterior ramus of the mandible, and elevates the mandible. The masseter muscle is the strongest muscle of the jaw, arising from the zygomatic arch and

inserting on the ramus and angle of the mandible. Its actions include elevation of the mandible (Figs. 2.92 and 2.93). The pterygoid muscles (medial and lateral) originate from the pterygoid processes of the sphenoid bone and insert on the angle of the mandible and condylar process, respectively. The medial pterygoid muscle acts to close the jaw, whereas the lateral pterygoid muscle opens the jaw and protrudes and moves the mandible from side to side (Figs. 2.92, 2.94, and 2.95).

Temporalis muscle

Lateral pterygoid muscle Medial pterygoid muscle Masseter muscle Angle of mandible

FIG. 2.92  Muscles of mastication.

Condyloid process of mandible Ramus of mandible

64

CHAPTER 2  Cranium and Facial Bones

S

Temporalis muscle R

L

Masseter muscle

Hard palate

Buccinator muscle

Tongue

I

FIG. 2.93  Coronal, T1-weighted MRI of muscles of mastication.

CHAPTER 2  Cranium and Facial Bones Lateral pterygoid muscle

Medial pterygoid muscle A

Masseter muscle

R

L

Condyloid process

P

FIG. 2.94  Axial, T1-weighted MRI of pterygoid muscles.

A

Pterygoid process of sphenoid bone Lateral pterygoid muscle

Masseter muscle

Temporalis muscle

L

R

Medial pterygoid muscle

P

FIG. 2.95  Axial CT of temporomandibular joint and muscles of mastication.

65

66

CHAPTER 2  Cranium and Facial Bones

PARANASAL SINUSES The paranasal sinuses are air-containing cavities within the facial bones and skull that communicate with the nasal cavity. The nasal cavity is lined by nasal mucosa and is responsible for filtering airborne particles as it

Sphenoid sinuses

warms and humidifies air going into the lungs. The sinuses are named after the bones in which they originate: ethmoid, maxillary, sphenoid, and frontal. There is great variance in the size, shape, and development of these sinuses within each individual (Figs. 2.96 and 2.97).

Frontal sinuses

Ethmoid sinuses

Maxillary sinus

FIG. 2.96  Anterior view of paranasal sinuses.

Frontal sinus

Posterior ethmoid sinus

Anterior ethmoid sinus Maxillary sinus

Sphenoid sinus

FIG. 2.97  Lateral view of paranasal sinuses.

CHAPTER 2  Cranium and Facial Bones

Ethmoid The ethmoid sinuses are contained within the lateral masses (labyrinths) of the ethmoid bone and number in the adult between 3 to 18 cells. They are present at birth and continue to grow and honeycomb into a varying number of air cells through puberty. The ethmoid sinuses

67

are divided into anterior and posterior groups by the basal lamella of the middle conchae (turbinates). The basal lamella is the lateral attachment of the middle nasal conchae to the lamina papyracea (Figs. 2.80 and 2.98). The anterior group drains into the middle nasal meatus, and the posterior group drains into the superior nasal meatus (Figs. 2.79, 2.80 and 2.96–2.100; Table 2.3).

A

Nasal bone

Lacrimal bone Ethmoid bone

Anterior ethmoid air cell

Zygoma Posterior ethmoid air cell

Lamina papyracea

Inferior orbital fissure

Sphenoid sinus

P

FIG. 2.98  Axial CT of sphenoid and ethmoid sinuses. Ethmoid sinuses

S

Frontal sinus Sphenoethmoidal recess

Pituitary gland

Superior nasal concha Superior nasal meatus

Sphenoid sinus A

P

Middle nasal concha Middle nasal meatus

Inferior nasal meatus

Inferior nasal concha

I

FIG. 2.99  Sagittal, T1-weighted MRI of sphenoid sinus.

68

CHAPTER 2  Cranium and Facial Bones S

Superior nasal meatus Ethmoid sinus

Ethmoid bulla

Middle nasal meatus

Middle nasal concha of ethmoid bone

Maxillary sinus

Inferior nasal concha

I

FIG. 2.100  Coronal CT of ethmoid and maxillary sinuses.

TABLE 2.3

Paranasal Sinus Drainage Location

Sinus

Drainage Location

Ethmoid: anterior Ethmoid: posterior Maxillary Sphenoid Frontal

Middle nasal meatus Superior nasal meatus Middle nasal meatus Sphenoethmoidal recess Middle nasal meatus

Inferior nasal meatus

CHAPTER 2  Cranium and Facial Bones

Maxillary The paired maxillary sinuses (antrum of Highmore) are located within the body of the maxilla, below the orbit and lateral to the nose. These triangular cavities are the largest of the paranasal sinuses in adults but are just small cavities at birth. Their growth stops at

Inferior nasal concha

A

69

approximately the age of 15. The roots of the teeth and the maxillary sinuses are separated by a very thin layer of bone. Often it is difficult to differentiate between the symptoms of sinusitis and infection of the teeth. The maxillary sinuses drain into the middle nasal meatus (Figs. 2.96, 2.97, 2.100, and 2.101; Table 2.3).

Nasolacrimal duct

Maxilla

Zygoma

Maxillary sinus

Perpendicular portion of palatine bone Pterygomaxillary fossa Pterygomaxillary fissure

Nasal septum

Pterygoid process

P

FIG. 2.101  Axial CT of maxillary sinuses.

70

CHAPTER 2  Cranium and Facial Bones

Sphenoid The sphenoid sinuses are present at birth but contain red marrow and are therefore devoid of air. Pneumatization of the sphenoid sinuses may be seen as early as 2 years of age. Major growth of the sinuses occurs in the third to fifth year, and they typically assume adult configuration between 10 and 14 years of age.

Sphenoid sinuses are normally paired and occupy the body of the sphenoid bone just below the sella turcica. Each sphenoid sinus opens into the sphenoethmoidal recess directly above the superior concha and drains into the superior nasal meatus (Figs. 2.80, 2.96–2.99, 2.102, and 2.103; Table 2.3).

S

Optic chiasm

R

L

Pituitary gland

Sphenoid sinus Internal carotid artery I

FIG. 2.102  Coronal, T1-weighted MRI of sphenoid sinuses. S

Optic canal Anterior clinoid process

Optic strut Sphenoid sinus

Superior orbital fissure

Zygomatic arch Middle nasal concha

Foramen rotundum

Inferior nasal concha Ramus of mandible Hard palate I

FIG. 2.103  Coronal CT of sphenoid sinuses.

CHAPTER 2  Cranium and Facial Bones

Frontal The frontal sinuses are located within the vertical portion of the frontal bone (Figs. 2.96, 2.97, and 2.99). These sinuses are typically paired and are separated along the sagittal plane by a septum (Fig. 2.104). The frontal

sinuses are rarely symmetric, vary greatly in size, and can contain numerous septa. These sinuses do not form or become aerated in the frontal bone until approximately age 6, making them the only paranasal sinuses that are absent at birth. The frontal sinuses drain into the middle nasal meatus (Figs. 2.99 and 2.100; Table 2.3).

Septum

S

Frontal sinus Nasal bone

Perpendicular plate of ethmoid bone

I

71

Frontal process of maxilla

FIG. 2.104  Coronal CT of frontal sinuses.

CHAPTER 2  Cranium and Facial Bones

72

Osteomeatal Unit Drainage of the paranasal sinuses occurs through various openings, or ostia. The major drainage pathways and structures of these osteomeatal channels form the osteomeatal unit (OMU) (Figs. 2.105–2.107). There are two osteomeatal channels: the anterior OMU and posterior OMU. The anterior OMU includes the ostia for the frontal and maxillary sinuses, frontal recess, infundibulum, and middle meatus. The anterior OMU provides communication between the frontal, anterior ethmoid,

Ethmoid sinus

and maxillary sinuses. The posterior OMU consists of the sphenoethmoidal recess and the superior nasal meatus, which communicate with the posterior ethmoid air cells. The sphenoethmoidal recess lies just lateral to the nasal septum, above the superior nasal concha, and drains the sphenoid sinuses. Key OMU structures to identify include the infundibulum, middle meatus, uncinate process, semilunar hiatus, and ethmoid bulla. The infundibulum is a narrow oblong canal that serves as the primary drainage pathway from the maxillary sinuses into the middle meatus. The medial wall of the

S Ethmoid bulla Infundibulum

Semilunar hiatus

Uncinate process of ethmoid bone

Middle nasal concha

Maxillary sinus L

R I

Inferior nasal concha

Middle nasal meatus

FIG. 2.105  Coronal view of osteomeatal unit.

S Crista galli

Roof of orbit

Orbital plate of frontal bone

Medial wall of orbit

Orbital plate of ethmoid bone (lamina papyracea)

Ethmoid bulla Lateral wall of orbit

Infundibulum

Semilunar hiatus Maxilla and floor of orbit

Zygoma L

R

Uncinate process

Maxillary sinus

Infraorbital groove Middle nasal meatus I

FIG. 2.106  Coronal CT of osteomeatal unit.

CHAPTER 2  Cranium and Facial Bones

Frontal recess

73

Ethmoid bulla

S

Semilunar hiatus Infundibulum

R

L

Maxillary sinus

Middle nasal meatus

I

Uncinate process

FIG. 2.107  Coronal CT of frontal recess. infundibulum is created by the uncinate process. The uncinate process is a thin, hook-shaped bony plate that arises from the floor of the anterior ethmoid sinuses and projects posteriorly and inferiorly, ending in a free edge. The free edge of the uncinate process forms the semilunar hiatus, which opens directly into the middle meatus. The semilunar hiatus is a gap located between the ethmoid bulla and uncinate process that forms the opening of the infundibulum. Also draining into the middle meatus is the ethmoid bulla, located superior and posterior to the infundibulum, which receives drainage from the anterior ethmoid air cells (Figs. 2.105–2.107).

ORBIT Bony Orbit The bony orbits are cone-shaped recesses that contain the globes, extraocular muscles, blood vessels, nerves, adipose and connective tissues, and most of the lacrimal apparatus. The junction of the frontal, sphenoid, and ethmoid bones of the cranium and the lacrimal, maxillary, palatine, and zygomatic bones of the face forms the orbit (Figs. 2.108 and 2.109). Each orbit presents a roof, floor, medial wall, lateral wall, and an apex. The roof of the orbit is composed of the orbital plate of the frontal bone and the lesser wing of the sphenoid bone. On the anterolateral surface of the roof is the lacrimal fossa where the lacrimal gland is located (Figs. 2.108 and 2.109). The medial wall is exceedingly thin and is formed by a portion of the frontal process of the maxilla, the lacrimal bone, the ethmoid bone, and the body of the sphenoid bone (Figs. 2.106–2.111). On the

anterior surface of the medial wall is the lacrimal groove for the lacrimal sac (Figs. 2.108–2.110). The floor of the orbit, which is also the roof of the maxillary sinus, is made up of the maxilla, zygoma, and palatine bones. The lateral wall is the thickest wall and is formed by the greater wing of the sphenoid bone and the zygoma (Figs. 2.106, 2.108, and 2.111). The posterior portion of the orbit or the apex is basically formed by the optic canal (optic foramen) and the superior orbital fissure. The optic canal and the superior and inferior orbital fissures allow various structures to enter and exit the orbit and establish communication between the orbit and middle cranial fossa. The optic canal forms an angle of about 37 degrees with the sagittal plane of the head; it is bound medially by the body, superiorly by the lesser wing, and inferiorly and laterally by the optic strut (inferior root) of the sphenoid bone (Figs. 2.108–2.112). Coursing through the optic canal are the ophthalmic artery and optic nerve. The superior orbital fissure, a triangular opening located between the greater and lesser wings of the sphenoid bone, allows the passage of cranial nerves, oculomotor (III), trochlear (IV), ophthalmic branch of the trigeminal (V), and abducens (VI), as well as the ophthalmic veins (Figs. 2.108, 2.109, 2.111, and 2.112). At the orbital apex, the inferior and lateral walls of the orbit are separated by the inferior orbital fissure through which the maxillary branch of the trigeminal nerve (V) courses (Figs. 2.108 and 2.113). The medial lip of the inferior orbital fissure is notched by the infraorbital groove, which passes forward in the orbital floor to become the infraorbital canal that opens on the anterior surface of the maxilla as the infraorbital foramen (Figs. 2.106 and 2.108–2.110).

74

CHAPTER 2  Cranium and Facial Bones

Roof

Orbital plate of ethmoid bone (lamina papyracea)

Supraorbital foramen

Orbital plate of frontal bone

S

Lacrimal bone

Lesser wing of sphenoid bone

Lacrimal groove

Greater wing of sphenoid bone

Frontal process of maxilla Nasal bone

Lateral wall R

L Medial wall

Zygoma

Optic canal Superior orbital fissure

Optic Strut

Inferior orbital fissure

Maxilla

I Infraorbital groove

Vertical portion of palatine bone

Floor

Infraorbital foramen

FIG. 2.108  Anterior view of bony orbit.

Lacrimal fossa

Lesser wing of Roof of sphenoid bone orbit

Orbital plate of frontal bone

Supraorbital foramen

Greater wing of sphenoid bone Medial wall Lateral wall

Nasal bone Lacrimal groove

Ethmoid bone Optic canal

Zygoma

Superior orbital fissure

Floor of orbit

Infraorbital foramen

Maxilla

FIG. 2.109  3D CT of bony orbit and optic canal, oblique view.

Optic strut

CHAPTER 2  Cranium and Facial Bones S Orbital plate of ethmoid bone Optic canal

Frontal sinus

Palatine bone

Orbital plate of frontal bone Nasal bone

Sella turcica of sphenoid bone

Lacrimal bone Lacrimal groove A

P

Frontal process of maxilla Infraorbital canal Infraorbital foramen Anterior nasal spine

Sphenoid bone (body) Foramen rotundum Pterygopalatine fossa

Maxillary sinus Alveolar process of maxilla

Pterygoid plate of sphenoid bone I

FIG. 2.110  Sagittal view of orbit and maxillary region.

A

Frontal process of maxilla Globe Nasal bones

Lacrimal bone Medial wall of orbit Zygoma Lateral wall of orbit Greater wing of sphenoid bone Superior orbital fissure

Optic canal

Anterior clinoid process

Body of sphenoid bone Dorsum sella P

FIG. 2.111  Axial CT of optic canal.

75

76

CHAPTER 2  Cranium and Facial Bones

Optic canal

Optic strut

S

Anterior Foramen Superior orbital fissure clinoid process rotundum

R

L Body of sphenoid bone

Greater wing of sphenoid bone

Pterygoid (vidian) canal

I

Sphenoid sinus

Pterygoid process of sphenoid bone

FIG. 2.112  Coronal CT reformat of superior orbital fissure and optic canal.

A Lacrimal bone Ethmoid bone

Zygoma

P

Inferior orbital fissure

FIG. 2.113  Axial CT of inferior orbital fissure.

Mandible

CHAPTER 2  Cranium and Facial Bones

Soft Tissue Structures The globe of the eye has an irregular, spherical shape and sits in the socket of the bony orbit. The globe is divided into anterior and posterior compartments (Fig. 2.114). The anterior compartment is a small cavity located anterior to the lens. It contains the cornea and iris and is filled with aqueous humor that helps maintain intraorbital pressure. The larger posterior compartment is located behind the lens and is surrounded by the retina. The retina consists of layers of tissue that include the photoreceptors responsible for vision. The posterior

chamber contains a jelly-like substance called the vitreous humor that helps maintain the shape of the globe (Figs. 2.114–2.125). Direct trauma to the globe will commonly result in a blowout fracture of the orbit. These fractures most commonly involve the floor of the orbit and cause orbital content herniation, which results in diplopia. A medial blowout fracture involving the orbital plate of the ethmoid bone is much less common but may cause open communication between the frontal and ethmoid sinuses and the orbit.

Anterior compartment with aqueous humor

Lacrimal sac

77

A Lens Ethmoid sinus

Posterior compartment with vitreous humor

Retina Medial

Lateral

Medial rectus muscle

Lateral rectus muscle

Retroorbital fat

P

Optic nerve in optic canal

FIG. 2.114  Axial view of the eye.

CHAPTER 2  Cranium and Facial Bones

78

Anterior chamber

Medial rectus muscle

A

Lacrimal sac

Lens

Posterior chamber

Retroorbital fat

Lateral rectus muscle

Optic nerve R

L

P

FIG. 2.115  Axial, T1-weighted MRI of orbit at midglobe.

Lens

Medial rectus muscle

A

Lacrimal sac

Anterior chamber with aqueous humor

Retina

Posterior chamber with vitreous humor

Retroorbital fat

Optic nerve

Lateral rectus muscle

R

L

P

FIG. 2.116  Axial CT of orbit at midglobe.

CHAPTER 2  Cranium and Facial Bones

Optic Nerve The optic nerve is the nerve of sight. It commences at the posterior surface of the globe and courses posteromedially to exit the orbit through the optic canal and is entirely surrounded by dura mater, which is continuous with the meninges of the brain (Figs. 2.114–2.116). The ophthalmic artery courses adjacent to the optic nerve as it exits

Frontal sinus

through the optic canal. The superior ophthalmic vein is located inferior to the superior rectus muscle and courses obliquely from the medial orbit through the superior orbital fissure, where it drains directly into the cavernous sinus (Figs. 2.117–2.119 and 2.122–2.124). Retroorbital fat surrounds the muscular and vascular structures within the orbit, which allows for better visualization of structures in cross-sectional imaging (Figs. 2.114–2.121).

Tendon of superior oblique muscle Globe

Lacrimal gland

Retroorbital fat

Medial rectus muscle

79

Lateral rectus muscle

Superior ophthalmic vein

FIG. 2.117  Axial view of orbit with lacrimal gland.

80

CHAPTER 2  Cranium and Facial Bones A

Globe Superior ophthalmic vein

Lacrimal gland

Retroorbital fat R

L

P

FIG. 2.118  Axial, T1-weighted MRI of orbit with lacrimal gland and superior ophthalmic vein.

A Lacrimal gland Superior ophthalmic vein Retroorbital fat

R

L

P

FIG. 2.119  Axial CT of orbit with lacrimal gland and superior ophthalmic vein.

CHAPTER 2  Cranium and Facial Bones

adduct the globe (Figs. 2.114–2.117 and 2.120–2.125). Two oblique muscles, superior and inferior, abduct and rotate the globe. The superior oblique is located medial to the superior rectus muscle, and the inferior oblique lies below and anterior to the inferior rectus muscle. The upper eyelid is controlled by the superior levator palpebrae muscle, which originates from the orbital roof near the origin of the superior rectus muscle (Figs. 2.120–2.125).

Muscles of the Eye Six major muscles work together to control the movement of the eye. The rectus muscle group consists of four muscles that arise from a common tendinous ring surrounding the optic nerve and is located at the medial portion of the superior orbital fissure. The superior, inferior, medial, and lateral rectus muscles act to abduct and S

81

Superior levator palpebrae muscle

Anterior compartment

Superior rectus muscle Retroorbital fat Optic nerve

Lens

A

P I

Globe

Inferior oblique muscle

Inferior rectus muscle

FIG. 2.120  Sagittal view of orbit. Superior rectus muscle

Optic nerve

S

Globe A

P

Lens Retroorbital fat

Inferior oblique muscle

Maxillary sinus

I

Inferior rectus muscle

FIG. 2.121  Sagittal oblique, T1-weighted MRI of orbit and optic nerve.

82

CHAPTER 2  Cranium and Facial Bones Superior rectus muscle

Superior oblique muscle

Superior ophthalmic vein

Superior levator palpebrae muscle

Ophthalmic artery Optic nerve Medial rectus muscle Lateral rectus muscle

Retroorbital fat Inferior rectus muscle

FIG. 2.122  Coronal view of orbit and optic nerve.

Ethmoid sinus

Superior oblique muscle

S

Superior ophthalmic vein

Superior rectus muscle

Medial rectus muscle Lateral rectus muscle

Retroorbital fat

Maxillary sinus

I

Ophthalmic Inferior artery rectus muscle

FIG. 2.123  Coronal CT of orbit with optic nerve and vessels.

CHAPTER 2  Cranium and Facial Bones Superior oblique muscle

S

83

Superior rectus muscle

Superior ophthalmic vein Retroorbital fat

Lateral rectus muscle

R

L

Ophthalmic artery

Optic nerve

I

Medial rectus muscle

Inferior rectus muscle

FIG. 2.124  Coronal, T1-weighted MRI of orbit with rectus muscle group.

Superior rectus muscle

S

Superior oblique muscle

Globe Lacrimal gland

R

L

Inferior oblique muscle

Inferior rectus muscle

I

Medial rectus muscle

FIG. 2.125  Coronal CT of globe and lacrimal gland.

84

CHAPTER 2  Cranium and Facial Bones

Lacrimal Apparatus Each lacrimal apparatus consists of a lacrimal gland, lacrimal canaliculi, lacrimal sac, and nasolacrimal duct and is responsible for the production and distribution of tears. Tears are important for keeping the eye moist and clean, removing waste, preventing bacterial infections, and providing nutrients and oxygen to portions of the eye. The almond-shaped lacrimal gland is located in the lacrimal groove, superior and lateral to the globe, where

Superior levator palpebrae muscle

it provides most of the tear volume (Figs. 2.117–2.119, 2.125, and 2.126). On blinking, tears collect in the area of the medial canthus and subsequently empty into small canals termed lacrimal canaliculi that lead to the lacrimal sac (Fig. 2.126). The lacrimal sac, found within the lacrimal groove of the orbit, continues inferiorly to form the nasolacrimal duct, which passes through the nasolacrimal canal of the maxillary and lacrimal bones to empty into the inferior nasal meatus (Figs. 2.115, 2.116, 2.126, and 2.127).

Tendon of superior oblique muscle and trochlea Medial canthus

Lacrimal gland Lacrimal sac Medial palpebral ligament, severed

Lateral palpebral ligament

Lacrimal canaliculi

Nasolacrimal duct

Inferior nasal concha Maxillary sinus

FIG. 2.126  Coronal view of lacrimal apparatus.

Inferior nasal meatus

CHAPTER 2  Cranium and Facial Bones

Perpendicular plate Ethmoid Cribriform of ethmoid bone sinuses plate

S

R

Crista galli

85

Orbital plate

L Middle nasal concha

Nasolacrimal duct

Maxillary sinus Vomer

Maxilla

I

FIG. 2.127  Coronal CT with nasolacrimal duct.

REFERENCES Abrahams, P. H., Marks, S. C., Jr., & Hutchings, R. T. (2003). McMinn’s color atlas of human anatomy (5th ed.). St. Louis: Mosby. Frank, G. (2012). Merrill’s atlas of radiographic positioning and procedures (12th ed.). St. Louis: Mosby. Harnsberger, H. R. (1995). Handbook of head and neck imaging (2nd ed.). St. Louis: Mosby.

Mosby. (2008). Mosby’s dictionary of medicine, nursing, and health professions (8th ed.). St. Louis: Mosby. Som, P. M., & Curtin, H. D. (2011). Head and neck imaging (5th ed.). St. Louis: Mosby. Standring, S. (2016). Gray’s anatomy: the anatomical basis of clinical practice (41st ed.). New York: Elsevier.

CHAPTER

3

Brain From the brain, and from the brain only, arise our pleasures, joys, laughter and jests, as well as our sorrows, pains, griefs, and tears. Hippocrates (460?–377?

bc),

The Sacred Disease

The brain regulates and coordinates many critical functions, from thought processes to bodily movements. For this reason, it is important to identify the anatomy of the brain (Fig. 3.1).

FIG. 3.1  Axial, T2-weighted MRI of brain with intraparenchymal hematoma in left basal nuclei.

OBJECTIVES • Describe the meninges. • Describe the production and absorption of cerebrospinal fluid. • Identify the components of the ventricular system. • Identify the basal cisterns. • List the structures of the diencephalon. • Describe the location and function of the components of the cerebrum, brainstem, and cerebellum.

• Identify the structures of the limbic system, and describe their function. • Identify the major arteries of the cerebrum, and list the structures they supply. • List the arteries that constitute the circle of Willis. • Identify the superficial cortical veins, deep veins, and dural sinuses of the cerebrum. • Identify the function and course of the cranial nerves.

OUTLINE MENINGES, 87 VENTRICULAR SYSTEM, 87 Ventricles, 87 Cisterns, 91 CEREBRUM, 99 Gray and White Matter Organization, 99 Cerebral Lobes, 100 Basal Nuclei, 106 DIENCEPHALON, 110 Thalamus, 110 Hypothalamus, 112 Pituitary Gland, 112 86

Epithalamus, 114 LIMBIC SYSTEM, 115 BRAINSTEM, 119 Midbrain, 120 Pons, 123 Medulla Oblongata, 125 CEREBELLUM, 127 CEREBRAL VASCULAR SYSTEM, 130 Arterial Supply, 130 Venous Drainage, 146 CRANIAL NERVES, 155 Olfactory Nerve (CN I), 157 Copyright © 2019, Elsevier Inc.

Optic Nerve (CN II), 158 Oculomotor Nerve (CN III), 160 Trochlear Nerve (CN IV), 163 Trigeminal Nerve (CN V), 163 Abducens Nerve (CN VI), 165 Facial Nerve (CN VII), 165 Vestibulocochlear Nerve (CN VIII), 168 Glossopharyngeal Nerve (CN IX), 168 Vagus Nerve (CN X), 168 Accessory Nerve (CN XI), 170 Hypoglossal Nerve (CN XII), 171

CHAPTER 3  Brain

MENINGES The brain is a delicate organ that is surrounded and protected by three membranes called the meninges (Fig. 3.2). The outermost membrane, the dura mater (tough mother), is the strongest. This double-layered membrane is continuous with the periosteum of the cranium. Located between the dura mater and the cranium are the meningeal vessels, which supply blood to the cranium and meninges. There is also a potential space between the dura mater and the cranium called the epidural (extradural) space. Located between the two layers of dura mater are the dural sinuses, which provide venous drainage from the brain. Folds of dura mater help to separate the structures of the brain and provide additional cushioning and support. The dural folds include the falx cerebri, tentorium cerebelli, and the falx cerebelli. The falx cerebri separates the cerebral hemispheres, whereas the tentorium cerebelli, which spreads out like a tent, forms a partition between the cerebrum and cerebellum. Lesions located above the tentorium cerebelli are considered supratentorial, and if they are located below, they are called infratentorial. An oval opening in the tentorium cerebelli forms the tentorial notch (incisura), which surrounds the midbrain and provides the only communication between the supratentorial and infratentorial spaces within the brain. The falx cerebelli separates the two cerebellar hemispheres (Figs. 3.3–3.6). The middle membrane, known as the arachnoid membrane (spiderlike), is a delicate, transparent membrane that is separated from the dura mater by a potential space called the subdural space. The arachnoid membrane follows the

$UDFKQRLGYLOOL

contour of the dura mater. The inner layer, or pia mater (delicate, tender mother), is a highly vascular layer that adheres closely to the contours of the brain. The subarachnoid space separates the pia mater from the arachnoid mater. This space contains cerebrospinal fluid that circulates around the brain and spinal cord and provides further protection to the central nervous system (CNS) (Fig. 3.2). Transtentorial herniation is the protrusion of brain tissue through the tentorial notch. It can occur as a result of increased intracranial pressure resulting from edema, hemorrhage, or tumor.

Skull fractures with rupture of the meningeal arteries can cause a life-threatening condition known as an epidural hematoma (EDH), which causes accumulation of blood in the epidural space between the dura and cranium. A subdural hematoma (SDH) is a collection of blood from ruptured vessels located in the subdural space.

VENTRICULAR SYSTEM Ventricles The ventricular system provides a pathway for the circulation of the cerebral spinal fluid (CSF) throughout the CNS. A major portion of the ventricular system is composed of four fluid-filled cavities (ventricles) located deep within the brain (Figs. 3.7–3.9). The two

'XUDOVLQXV

&UDQLXP

$UDFKQRLG JUDQXODWLRQ

'XUDPDWHU $UDFKQRLG PHPEUDQH 3LDPDWHU

6XEDUDFKQRLG VSDFH

&HUHEUDO FRUWH[ )DO[FHUHEUL

87

FIG. 3.2  Coronal cross-section of meninges and subarachnoid space.

0HQLQJHV

88

CHAPTER 3  Brain Falx cerebri Inferior sagittal sinus

Superior sagittal sinus

Straight sinus

Cavernous sinus

Confluence of sinuses Tentorium cerebelli

Infundibulum

Great cerebral vein Transverse sinus Cerebellum

Optic nerve

Tentorial notch (incisura) Midbrain

Dorsum sella

Olfactory bulb

FIG. 3.3  Dural reflections and venous sinuses.

Frontal lobe

A

Falx cerebri Lateral ventricle

Third ventricle

R

L Tentorium cerebelli

Cerebellum

P

FIG. 3.4  Axial CT of falx cerebri and tentorium cerebelli.

Location of crista galli

CHAPTER 3  Brain S

Falx cerebri

Cerebrum R

L Tentorium cerebelli Cerebellum

I

FIG. 3.5  Coronal, T1-weighted MRI of falx cerebri and tentorium cerebelli.

Dura mater

S

Cerebrum

Subarachnoid space

Tentorium cerebelli

A

P

Falx cerebelli

Cerebellum

I

FIG. 3.6  Sagittal, T1-weighted MRI of tentorium cerebelli.

89

90

CHAPTER 3  Brain Interventricular foramen Massa intermedia (foramen of Monro) Frontal horn of lateral ventricle

Trigone (atria)

Occipital horn of lateral ventricle

Lamina terminalis

Cerebral aqueduct (aqueduct of Sylvius)

Third ventricle Temporal horn of lateral ventricle

Median aperture (foramen of Magendie)

Fourth ventricle

Central canal

FIG. 3.7  Lateral view of ventricular system.

Body of lateral ventricle Frontal horn of lateral ventricle

Interventricular foramen (foramen of Monro)

Third ventricle

Temporal horn of lateral ventricle

Cerebral aqueduct (aqueduct of Sylvius)

Lateral aperture (foramen of Luschka)

Fourth ventricle Central canal

FIG. 3.8  Anterior view of ventricular system.

CHAPTER 3  Brain

91

A Frontal horn of lateral ventricle

Third ventricle Body of lateral ventricle

Temporal horn of lateral ventricle

R

L Occipital horn of lateral ventricle

Fourth ventricle

Lateral aperature (foramen of Luschka) P

FIG. 3.9  Superior view of ventricles in relation to surface of brain.

most superior cavities are the right and left lateral ventricles. These ventricles lie within each cerebral hemisphere and are separated at the midline by a thin membrane known as the septum pellucidum (Figs. 3.10 and 3.11). The lateral ventricles consist of a central portion called the body and three extensions: the frontal (anterior), occipital (posterior), and temporal (inferior) horns (Figs. 3.7–3.16). The junction of the body and the occipital and temporal horns form a triangular area termed the trigone (atria). The lateral ventricles communicate inferiorly with the third ventricle via the paired interventricular foramen (foramen of Monro) (Figs. 3.7, 3.8, and 3.10). The third ventricle is a thin, slitlike structure, located midline just inferior to the lateral ventricles (Figs. 3.7–3.11). The anterior wall of the third ventricle is formed by a thin membrane termed the lamina terminalis, and the lateral walls are formed by the thalamus. The third ventricle communicates with the fourth ventricle via a long, narrow passageway termed the cerebral aqueduct (aqueduct of Sylvius). The cerebral aqueduct reaches the fourth ventricle by traversing the posterior portion of the midbrain (Figs. 3.7, 3.8 and 3.13). The fourth ventricle is a diamond-shaped cavity located anterior to the cerebellum and posterior to the pons (Figs. 3.7, 3.8, and 3.12–3.16). Separating the fourth ventricle from the cerebellum is a thin membrane forming the superior and inferior medullary velum (Fig. 3.13). CSF exits the ventricular system through foramina in the fourth ventricle to communicate with the subarachnoid space within the basal cisterns. The major exit route is the median aperture (foramen of Magendie), located on the posterior wall of the fourth ventricle, which communicates with the cisterna magna (Figs. 3.7 and 3.17). There are two lateral apertures, termed the foramen of Luschka, which communicate with the cerebellopontine

angle cistern. From the fourth ventricle, CSF continues into the spinal cord via the central canal (Figs. 3.8 and 3.17). The septum pellucidum is frequently used as a landmark to determine if the midline of the brain has shifted as a result of trauma or increased cranial pressure.

Located within the ventricular system is a network of blood vessels and nerve cells termed the choroid plexus, which produces CSF. The choroid plexus lines the floor of the lateral ventricles, roof of the third ventricle, and inferior medullary velum of the fourth ventricle (Fig. 3.17). Frequently, the choroid plexus is partially calcified, making it more noticeable on computed tomography (CT) images (Figs. 3.18 and 3.19). There exists a continuous circulation of CSF in and around the brain. Excess CSF is reabsorbed in the dural sinuses by way of arachnoid villi. These villi are berry-like projections of arachnoid tissue that penetrate the dura mater (Figs. 3.2 and 3.17). Enlargements of the arachnoid villi are termed granulations. Within the cranium, these granulations can cause pitting or depressions, which are variations of normal anatomy.

Cisterns The subarachnoid space is a relatively narrow, fluidfilled space surrounding the brain and spinal cord. There are locations, primarily around the base of the brain, where the subarachnoid space becomes widened (Fig. 3.17). The combined term for these widened areas or pools of CSF is the basal (subarachnoid) cisterns (Fig. 3.20). Each cistern is generally named after the brain structure it borders.

92

CHAPTER 3  Brain A

Frontal horn of lateral ventricle

Septum pellucidum

Interventricular foramen

R

L Thalamus

Third ventricle

Occipital horn of lateral ventricle

P

Choroid plexus

FIG. 3.10  Axial, T1-weighted MRI of lateral and third ventricles. A

Frontal horn of lateral ventricle Septum pellucidum Third ventricle

R

L

Thalamus

P

FIG. 3.11  Axial CT of lateral and third ventricles.

CHAPTER 3  Brain Temporal horn of lateral ventricle

A

Frontal lobe

Temporal lobe

Pons R

L

Fourth ventricle

P

Cerebellum

Petrous portion of temporal bone

FIG. 3.12  Axial CT of temporal horns of the lateral ventricles.

Lateral ventricle

S

Suprasellar cistern

Thalamus A

P Cerebral aqueduct Cerebellum Superior medullary velum Fourth ventricle

Midbrain

Pons

Medulla oblongata

I

Cisterna magna

FIG. 3.13  Midsagittal T1-weighted MRI of ventricular system.

Inferior medullary velum

93

94

CHAPTER 3  Brain A

R

L

Pons

Tentorium cerebelli

Fourth ventricle

P

Cisterna magna

Cerebellum

FIG. 3.14  Axial CT of fourth ventricle.

Corpus callosum

S

Falx cerebri

Lateral ventricle

Lateral fissure

Third ventricle R

L Optic tract

Temporal horn of lateral ventricle

Basilar artery

I

FIG. 3.15  Coronal, T2-weighted MRI of temporal horns of the lateral ventricles.

CHAPTER 3  Brain Falx cerebri

S

Occipital horn of lateral ventricle with choroid plexus

R

L

Tentorium cerebelli

Cerebellum

Fourth ventricle

I

Medulla oblongata

FIG. 3.16  Coronal, T1-weighted MRI of lateral and fourth ventricles. Corpus callosum Superior sagittal sinus

Dura mater Choroid plexus of lateral ventricle

Arachnoid granulation

Interventricular foramen Anterior commissure

Subarachnoid space

Lamina terminalis Choroid plexus of third ventricle

Suprasellar cistern Quadrigeminal cistern

Superior medullary velum

Midbrain

Cerebellum

Cerebral aqueduct

Inferior medullary velum Choroid plexus of fourth ventricle

Pons Prepontine cistern

Median aperture of fourth ventricle

Medulla oblongata Central canal

Cisterna magna

FIG. 3.17  Sagittal view of choroid plexus and flow of CSF through the ventricular system.

95

CHAPTER 3  Brain

96

Septum pellucidum

A

R

L Choroid plexus

Occipital horn of lateral ventricle

P

FIG. 3.18  Axial CT of lateral ventricles with calcified choroid plexus.

Lateral ventricle

S

Calcified choroid plexus

Tentorium cerebelli R

L

Cerebellum

I

Fourth ventricle

FIG. 3.19  Coronal CT reformat of calcified choroid plexus in lateral ventricles.

One of the largest cisterns is the cisterna magna. It is located in the lower posterior fossa bordered by the medulla oblongata, cerebellar hemispheres, and occipital bone. It is continuous with the subarachnoid space of the spinal canal (Figs. 3.13, 3.14, and 3.17). The

interpeduncular cistern is located between the cerebral peduncles of the midbrain and communicates inferiorly with the prepontine cistern (Figs. 3.20–3.22). The prepontine cistern is located just anterior and inferior to the pons and communicates laterally with the

CHAPTER 3  Brain cerebellopontine angle (CPA) cistern (Figs. 3.17, 3.23, and 3.24). The CPA cistern is located at the junction of the pons and cerebellum. It contains important structures, including CNs V, VII, and VIII and the superior and anterior inferior cerebellar arteries. The ambient cistern courses around the lateral surface of the midbrain, connecting the interpeduncular cistern with the quadrigeminal (superior) cistern (Figs. 3.20–3.22). The quadrigeminal cistern lies between the splenium of the corpus callosum and the superior surface of the cerebellum just posterior to the colliculi of the midbrain or the tectum (quadrigeminal plate) (Figs. 3.20 and 3.21). Located

above the sella turcica is the suprasellar (chiasmatic) cistern, which contains the optic chiasm and the circle of Willis (Figs. 3.13, 3.17, and 3.20–3.22). Bleeding within the subarachnoid space is called a subarachnoid hemorrhage (SAH). The most common cause of an SAH is a ruptured aneurysm. Patients with this condition will commonly present to the emergency department complaining of the worst headache of their lives. Blood within the subarachnoid space acts as a chemical irritant to the brain and causes an increase in intracranial pressure.

Subarachnoid space Longitudinal fissure

Frontal lobe Lateral (Sylvian) fissure

Temporal lobe Interpeduncular cistern Cerebral peduncle

Suprasellar cistern Ambient cistern

Tectum (quadrigeminal plate)

Cerebral aqueduct

Midbrain

Vermis

Quadrigeminal cistern

Cerebellar hemisphere

Cisterna magna

FIG. 3.20  Axial view of basal cisterns.

A Lateral fissure

Cerebral peduncle of midbrain

Middle cerebral artery

Posterior cerebral artery

Suprasellar cistern Interpeduncular cistern L

R

Midbrain Tectum

Ambient cistern Quadrigeminal cistern

Cerebral aqueduct

97

Vermis of cerebellum P

FIG. 3.21  Axial, T2-weighted MRI of ambient, suprasellar, and interpeduncular cisterns.

98

CHAPTER 3  Brain A

Suprasellar cistern Interpeduncular cistern

Lateral fissure

Cerebral peduncle of midbrain

R

L

Middle cerebral artery

Midbrain

Posterior cerebral artery

Ambient cistern

Tectum

P

Superior aspect of fourth ventricle

FIG. 3.22  Axial CT of ambient, suprasellar, and interpeduncular cisterns. A Basilar artery

Prepontine cistern Cerebellopontine angle (CPA) cistern

Pons

R

L

Internal auditory canal

Cerebellum

Fourth ventricle

P

FIG. 3.23  Axial, T2-weighted MRI of cerebellopontine angle (CPA) cistern.

CHAPTER 3  Brain

A

99

Frontal sinus

Left orbit

Sella turcica

Pons R

L

Basilar artery in prepontine cistern Cerebellopontine angle cistern

Fourth ventricle

P

Cisterna magna

Cerebellum

FIG. 3.24  Axial CT of cerebellopontine angle (CPA) cistern.

CEREBRUM The cerebrum is the largest portion of the brain and is divided into left and right cerebral hemispheres. Each hemisphere contains neural tissue arranged in numerous folds called gyri. The gyri are separated by shallow grooves called sulci and by deeper grooves called fissures. The main sulcus that can be identified on CT and magnetic resonance images (MRIs) of the brain is the central sulcus, which divides the precentral gyrus of the frontal lobe and postcentral gyrus of the parietal lobe (Figs. 3.25 and 3.26). These gyri are important to identify because the precentral gyrus is considered the motor strip of the brain and the postcentral gyrus is considered the sensory strip of the brain. Other gyri important for imaging include the cingulate, parahippocampal, and superior temporal gyrus (see limbic system and temporal lobe). The two main fissures of the cerebrum are the longitudinal fissure and the lateral (Sylvian) fissure (Figs. 3.27 and 3.28). The longitudinal fissure is a long, deep furrow that divides the left and right cerebral hemispheres. Located in this fissure are the falx cerebri and superior and inferior sagittal sinuses. The lateral fissure is a deep furrow that separates the frontal and parietal lobes from the temporal

lobe. Numerous blood vessels, primarily branches of the middle cerebral artery, follow the course of the lateral fissure (Figs. 3.21, 3.22, and 3.25–3.28).

Gray and White Matter Organization The cerebrum as a whole has many critically important functions, including thought, judgment, memory, and discrimination. The cerebrum consists of gray matter (neuron cell bodies) and white matter (myelinated axons) (Figs. 3.27 and 3.28). The cerebral cortex, the outermost portion of the cerebrum, is composed of gray matter approximately 3 to 5 mm thick. The cortex not only receives sensory input but also sends instructions to the muscles and glands for control of body movement and activity. Deep in the cortex is the white matter, which contains fibers that create pathways for the transmission of nerve impulses to and from the cortex. The largest and densest bundle of white matter fibers within the cerebrum is the corpus callosum. This midline structure forms the roof of the lateral ventricles and connects the right and left cerebral hemispheres. The four parts of the corpus callosum, from anteroinferior to posterior, are the rostrum, genu, body, and splenium (Figs. 3.29–3.32).

100

CHAPTER 3  Brain Precentral gyrus

Central sulcus Postcentral gyrus Parietal lobe

Gyrus

Sulcus Frontal lobe

Occipital lobe

Lateral (Sylvian) fissure Temporal lobe Pons

Cerebellum

FIG. 3.25  Lateral view of central sulcus.

Broca’s area

S

Precentral gyrus

Central sulcus Postcentral gyrus Parietal lobe

A

P

Frontal lobe

Occipital lobe

Cerebellum Lateral fissure

Temporal lobe

I

FIG. 3.26  Sagittal, T1-weighted MRI of cerebral lobes and central sulcus.

Two other important bundles of white matter fibers are the anterior and posterior commissures (Figs. 3.29 and 3.30). The anterior commissure crosses the midline within the lamina terminalis and connects the anterior portions of each temporal lobe (Figs. 3.29, 3.30, 3.33, and 3.34). The posterior commissure is a pathway made of several fibers that transmit nerve impulses for pupillary (consensual) light reflexes. This pathway crosses the midline posterior to the third ventricle, immediately above the cerebral aqueduct and inferior to the pineal gland (Figs. 3.29, 3.30, and 3.34).

Cerebral Lobes The cerebral cortex of each hemisphere can be divided into four individual lobes: frontal, parietal, occipital, and temporal (Fig. 3.35). These four lobes correspond in location to the cranial bones with the same name. Each lobe has critical regions that are associated with specific functions. The frontal lobe is the most anterior lobe of the brain. The boundaries of the frontal lobe are the central sulcus, which separates it from the parietal lobe, and the lateral fissure, which separates it from the temporal lobe (Figs. 3.25, 3.26, 3.35, and 3.36). The frontal

CHAPTER 3  Brain

Cerebral cortex (gray matter)

Longitudinal fissure Cingulate gyrus

Corpus callosum

Frontal lobe

White matter

Frontal horn of lateral ventricle

Head of caudate nucleus

Thalamus

Claustrum

Insula Superior temporal gyrus

Third ventricle

Extreme capsule

Lateral fissure

External capsule Temporal lobe

Putamen Lentiform nucleus

Optic tract

Globus pallidus Parahippocampal gyrus

Mamillary bodies

Internal capsule

FIG. 3.27  Coronal view of cerebrum.

S

Longitudinal fissure Cingulate gyrus

Parietal lobe

White matter Lateral ventricle Thalamus

Lateral fissure

Superior temporal gyrus

Insula R

L Third ventricle

Temporal lobe

Cerebral cortex (gray matter)

I

Parahippocampal gyrus

FIG. 3.28  Coronal, T1-weighted MRI of cerebrum.

101

102

CHAPTER 3  Brain Body of corpus callosum

Cingulate gyrus

Third ventricle Splenium of corpus callosum

Pineal gland

Genu of corpus callosum

Cerebral aquaduct Rostrum of corpus callosum

Fourth ventricle

Anterior commissure Posterior commissure

Lamina terminalis Mass intermedia

FIG. 3.29  Midsagittal view of corpus callosum. Genu of corpus callosum

Body of corpus callosum

Anterior commissure

Thalamus

Splenium of corpus callosum

A

P

Rostrum of corpus callosum

Mamillary body

I

Posterior commissure

Pineal gland

FIG. 3.30  Midsagittal, T1-weighted MRI of corpus callosum. lobe mediates a wide variety of functions, such as reasoning, judgment, emotional response, planning and execution of complex actions, and control of voluntary muscle movement. The frontal lobe is also involved in speech production and contains the motor speech (language) center, Broca’s area. Broca’s area lies unilaterally

on the inferior surface of the frontal lobe dominant for language, typically in the left inferior frontal gyrus (Fig. 3.35). This area is involved in the coordination or programming of motor movements for the production of speech sounds. The parietal lobe is located in the middle portion of each cerebral hemisphere just posterior to the

CHAPTER 3  Brain A

Longitudinal fissure

Genu of corpus callosum Septum pellucidum L

R Insula

Third ventricle

Thalamus

Splenium of corpus

P

FIG. 3.31  Axial, T1-weighted MRI of corpus callosum. S

Gray matter of cerebral cortex

Longitudinal fissure Body of corpus callosum

White matter

Lateral ventricle Superior temporal gyrus

Insula R

L Suprasellar cistern

I

FIG. 3.32  Coronal, T1-weighted MRI of cerebral cortex and corpus callosum.

103

104

CHAPTER 3  Brain Frontal lobe

Frontal horn of lateral ventricle

Genu of corpus callosum Anterior commissure

Third ventricle

Insula

Temporal lobe

Thalamus

Cerebral cortex (gray matter)

Occipital lobe

FIG. 3.33  Axial view of cerebral cortex and corpus callosum.

A

Anterior commissure

Thalamus

Insula R

L

Third ventricle

Posterior commissure

Occipital horn of lateral ventricle

P

FIG. 3.34  Axial, T2-weighted MRI of anterior and posterior commissures.

CHAPTER 3  Brain Precentral gyrus Primary motor cortex

Frontal lobe Personality Behavior Emotion Intellectual functions

Longitudinal fissure

Frontal lobe (retracted)

Central sulcus S Postcentral gyrus Primary somatosensory cortex

Sulcus

Parietal lobe Sensation

Broca’s area Motor speech area Right cerebral hemisphere

105

Parieto-occipital sulcus A

P

Gyrus Occipital lobe Primary visual cortex Visual association area

Left cerebral hemisphere Inferior frontal gyrus Insula Visceral effects

Lateral fissure

Superior temporal gyrus Heschl’s gyrus

Wernicke’s area (language comprehension) Temporal lobe Hearing, smell Primary auditory cortex Primary olfactory cortex

Temporal lobe (retracted) I

FIG. 3.35  Lateral view of cerebral lobes.

central sulcus. The horizontal portion of the lateral fissure separates the parietal lobe from the temporal lobe (Figs. 3.25, 3.26, 3.28, and 3.37). The parietal lobe is associated with the perception of temperature, touch, pressure, vibration, pain, and taste and is involved in writing and in some aspects of reading. The most posterior lobe, the occipital lobe, is separated from the parietal lobe by the parieto-occipital fissure. This lobe is involved in the conscious perception of visual stimuli. The primary visual area receives input from the optic tract via the optic radiations extending from the thalamus (Fig. 3.36). The temporal lobe is anterior to the occipital lobe and is separated from the parietal lobe by the lateral fissure (Fig. 3.37). Conscious perceptions of auditory and olfactory stimuli and dominance for language are functions of the temporal lobe. Memory processing occurs via the amygdala and hippocampus, clusters of gray matter located in the parahippocampal gyrus of the temporal lobe (Figs. 3.27 and 3.28). Located on the superior temporal gyrus is the auditory cortex, which can be divided into primary and secondary auditory areas (Figs. 3.27, 3.32, and 3.35). The primary auditory area, Heschl’s gyrus, receives the major auditory sensory information from the bilateral cochlea, whereas the secondary auditory area, Wernicke’s area, is the center for comprehension and formulation of speech (Fig. 3.35). Deep in the temporal lobe is another area of cortical gray matter termed the insula (island of Reil), often referred to as the fifth lobe. The insula is separated from the temporal lobe by the lateral fissure and is

thought to mediate motor and sensory functions of the viscera (Figs. 3.27, 3.28, and 3.31–3.38). Studies in neuroimaging have found correlations between structural abnormalities and decreased gray matter volume of the superior temporal gyrus in individuals with schizophrenia and autism.

A Frontal lobe

Lateral fissure Temporal lobe

Insula

L

R

Thalamus Posterior commissure Optic radiations Occipital lobe P

FIG. 3.36  Axial, T1-weighted MRI of cerebral lobes.

106

CHAPTER 3  Brain

Parietal lobe

S

Lateral ventricle

Suprasellar cistern

Lateral fissure L

R

Insula Temporal lobe

I

Sphenoid sinus

FIG. 3.37  Coronal CT reformat of cerebral lobes.

Basal Nuclei The basal nuclei (ganglia) are a collection of subcortical gray matter consisting of the caudate nucleus, lentiform nucleus, and claustrum (Figs. 3.27, 3.39, and 3.40). Collectively, they contribute to the planning and programming of muscle action and movement. The largest basal nuclei are the caudate nucleus and lentiform nucleus. Both nuclei serve as relay stations between the thalamus and the cerebral cortex of the same side. The caudate nucleus parallels the lateral ventricle and consists of a head, body, and tail. The head causes an indentation to the frontal horns of the lateral ventricles, and the tail terminates at the amygdala in the temporal lobe (Figs. 3.40–3.44). The lentiform nucleus is a biconvex lens–shaped mass of gray matter located among the insula, caudate nucleus, and thalamus. The lentiform nucleus can be further divided into the globus pallidus and the putamen (Figs. 3.41 and 3.42). The claustrum is a thin linear layer of gray matter lying between the insula and the lentiform nucleus and is thought to be involved in the mediation of visual attention (Figs. 3.41–3.44).

Basal nuclei disease or dysfunction causes symptoms of difficulty starting, stopping, or sustaining movement and problems with memory and thought processes. Brain disorders associated with basal nuclei dysfunction include Huntington disease, Wilson disease, dystonia, and Parkinson disease. Injuries to the brain that can also cause damage to the basal nuclei are many and include stroke, tumors, carbon monoxide poisoning, liver disease, infection, and drug overdose.

Three large tracts of white matter, the internal, external, and extreme capsules, separate the basal nuclei and transmit electrical impulses throughout the brain. The internal capsule is shaped like a boomerang and separates the thalamus and caudate nucleus from the lentiform nucleus. The external capsule is a thin layer of white matter that separates the claustrum from the lentiform nucleus. Another thin layer of white matter located between the claustrum and insular cortex is the extreme capsule (Figs. 3.40–3.44). The basal nuclei allow for the unconscious coordination of swinging our arms in rhythm with our legs as we walk.

CHAPTER 3  Brain

A

Frontal lobe

Lateral fissure

Insula

Temporal lobe R

L

Quadrigeminal cistern

P

Cerebellum

FIG. 3.38  Axial CT of cerebral lobes.

Body Thalamus

Head of caudate nucleus

Lentiform nucleus Amygdala

Tail of caudate nucleus

FIG. 3.39  Lateral view of basal nuclei.

107

108

CHAPTER 3  Brain

Lentiform nucleus

Internal capsule

S

Body of caudate nucleus

Thalamus

Head of caudate nucleus Frontal horn of lateral ventricle

A

P

Amygdala Hippocampus

I

FIG. 3.40  Sagittal, T2-weighted MRI with basal nuclei.

Frontal horn of lateral ventricle

Head of caudate nucleus Claustrum

Internal capsule

Insula Extreme capsule Putamen

Fornix Globus pallidus

Lentiform nucleus

External capsule Splenium of corpus callosum Thalamus

Occipital horn of lateral ventricle

Tail of caudate nucleus

FIG. 3.41  Axial view of basal nuclei.

CHAPTER 3  Brain A Head of caudate nucleus

Internal capsule External capsule Claustrum

Insula

Globus pallidus

Thalamus R

L

Lentiform nucleus Putamen

Pineal gland

P

FIG. 3.42  Axial, T1-weighted MRI of basal nuclei.

A Fornix

Head of caudate nucleus

External capsule Insula

Lentiform nucleus L

R

Internal capsule

Thalamus

P

FIG. 3.43  Axial CT of basal nuclei.

109

110

CHAPTER 3  Brain

S Corpus callosum

Septum pellucidum

Head of caudate nucleus

Internal capsule Lentiform nucleus External capsule R

L Optic chiasm

Claustrum Pituitary gland

I

FIG. 3.44  Coronal, T1-weighted MRI of basal nuclei.

DIENCEPHALON

Thalamus

The diencephalon is a complex of structures within the brain; its major components are the thalamus and hypothalamus. The diencephalon functions as a relay station for sensory information and as an interactive site between the central nervous and endocrine systems, and it is closely associated with the limbic system.

The thalamus consists of a pair of large oval gray masses that are interconnected with most regions of the brain and spinal cord via a vast number of fiber tracts. The thalamus makes up a portion of the walls of the third ventricle and connects through the middle of the third ventricle by adhesions known as the massa intermedia (Figs. 3.45 and 3.46). The thalamus serves as a relay

CHAPTER 3  Brain S Lateral ventricle

Third ventricle

Fornix

Body of corpus callosum Choroid plexus of third ventricle

Cingulate gyrus Genu of corpus callosum

Massa intermedia Splenium of corpus callosum

Rostrum of corpus callosum A

P Pineal gland

Anterior commissure

Posterior commissure

Optic chiasm

Cerebral aqueduct

Infundibulum Pituitary gland

Midbrain

Pons

Anterior lobe Posterior lobe

Fourth ventricle Medulla oblongata

Mamillary body

Central canal

I S Fornix

Septum pellucidum

Anterior commissure

Paraventricular nucleus Massa intermedia

Lamina terminalis

Posterior nucleus

Dorsomedial nucleus

Thalamus

Preoptic nucleus Ventromedial nucleus

A

P

Lateral hypothalamic area Midbrain

Supraoptic nuclei

Red nucleus

Optic tract Infundibular nucleus Optic nerve

Pons Lateral tuberal nuclei Infundibulum

Mamillary body

Oculomotor nerve

I

FIG. 3.45  Sagittal view of hypothalamus and hypothalamic nuclei. Box indicates close-up view of the hypothalamic nuclei.

111

112

CHAPTER 3  Brain

Fornix

Cerebral peduncle of midbrain

Posterior commissure Pineal gland

S

Superior colliculi

Inferior colliculi

Thalamus Hypothalamus Mamillary body

Cerebral aqueduct

Optic nerve A

P Fourth ventricle

Infundibulum Anterior lobe Pituitary gland Posterior lobe

Cerebellum

Suprasellar Pons cistern

I Medulla Cerebellar oblongata Spinal tonsil cord

FIG. 3.46  Midsagittal, T1-weighted MRI of brainstem.

station to and from the cerebral cortex for all sensory stimuli, with the exception of the olfactory nerves (Figs. 3.27–3.31 and 3.39–3.43).

Hypothalamus The hypothalamus consists of a cluster of small but critical nuclei located below the thalamus just posterior to the optic chiasm, forming the floor of the third ventricle. Anatomically, it includes the optic chiasm, mamillary bodies, and infundibulum, and it is functionally related to the pituitary gland (Figs. 3.45 and 3.46). The hypothalamus functions in integrating the activities of the autonomic, endocrine, and limbic systems by helping to maintain homeostasis as it controls regulation of temperature, appetite, sexual drive, and sleep patterns. In addition, the hypothalamus modulates the activities of the anterior and posterior lobes of the pituitary gland via the release of neurohormones, which stimulate or inhibit the release of pituitary hormones.

Pituitary Gland The pituitary gland (hypophysis) is an endocrine gland connected to the hypothalamus by the infundibulum.

The infundibulum is a slender stalk located between the optic chiasm and the mamillary bodies (Figs. 3.45 and 3.46). The pituitary gland is located in the sella turcica at the base of the brain (Figs. 3.45–3.49). The protected location of this gland suggests its importance. It is sometimes called the master gland because it controls and regulates the functions of many other glands through the action of its six major types of hormones. The hypothalamus sends signals to the pituitary gland to stimulate or inhibit hormone production. The pituitary gland can be broken down into an anterior lobe (adenohypophysis) and a posterior lobe (neurohypophysis) (Fig. 3.46). The anterior lobe synthesizes and releases six hormones: growth hormone (GH), prolactin (PRL), follicle-stimulating hormone (FSH), luteinizing hormone (LH), adrenocorticotropic hormone (ACTH), and thyroid-stimulating hormone (TSH). These six hormones help to regulate the function of other endocrine glands that influence growth, blood pressure, metabolism, temperature regulation, the reproductive glands, and response to stress. The posterior lobe does not produce hormones directly but releases into circulation two hormones that are synthesized in the hypothalamus. These hormones are antidiuretic hormone (ADH), which is commonly called vasopressin, and oxytocin.

CHAPTER 3  Brain

Insula

Corpus callosum

S

Lateral ventricle

Head of caudate nucleus

Lentiform nucleus

Optic chiasm

Lateral fissure

Infundibulum

Temporal lobe R

L

Anterior commissure

Pituitary gland

Suprasellar cistern

I

FIG. 3.47  Coronal, T1-weighted MRI of pituitary gland and optic chiasm.

S

Anterior cerebral artery

Optic chiasm

Infundibulum Suprasellar cistern R

L

Internal carotid artery (clinoid segment)

Pituitary gland

Internal carotid artery (cavernous segment)

I

Sphenoid sinus

Meckel’s cave

FIG. 3.48  Coronal CT reformat of pituitary gland.

113

114

CHAPTER 3  Brain A

Temporal lobe

Internal carotid artery

Pituitary gland R

L Basilar artery

Prepontine cistern

Vermis of cerebellum

Pons

Occipital lobe P

FIG. 3.49  Axial, proton density–weighted MRI of pituitary gland.

Epithalamus The epithalamus is the most posterior portion of the diencephalon and comprises the posterior commissure and pineal gland. The pineal gland, an endocrine structure, secretes the hormone melatonin, a serotonin-derived hormone that aids in the regulation of circadian rhythms. Melatonin also helps regulate the

reproductive hormones LH and FSH. The pineal gland sits on the roof of the midbrain just posterior to the third ventricle and below the splenium of the corpus callosum. It is sometimes calcified, which aids in its detection on CT scans and lateral radiographs of the cranium (Figs. 3.29, 3.30, 3.45, 3.46, 3.50, and 3.51). A

Anterior commissure R

L Posterior commissure

Third ventricle Occipital horn of lateral ventricle

Pineal gland

P FIG. 3.50  Axial, T2-weighted MRI of pineal gland.

CHAPTER 3  Brain

115

A Third ventricle Calcified pineal gland

R

L Occipital horn of lateral ventricle Calcified choroid plexus P FIG. 3.51  Axial CT with calcified pineal gland. Corpus callosum

Cingulate gyrus

Fornix

Anterior thalamic nuclei

Septum pellucidum Septal nuclei Anterior commissure

Mamillary body

Olfactory bulb Olfactory tract Hypothalamus Amygdala

Parahippocampal gyrus

Hippocampus

FIG. 3.52  Lateral view of limbic system within the brain.

LIMBIC SYSTEM The limbic system is a complex group of interconnected brain structures and fiber tracts located within and adjacent to the medial surface of the temporal lobes. These structures contain critical connecting pathways that extend to other areas deep within the midbrain, basal nuclei, and cerebral hemispheres (Figs. 3.52–3.57). They have a common functional role in the emotional aspects of behavior. Particularly, the limbic system is involved in aggression, submissive and sexual behavior, memory,

learning, and general emotional responses. Structures of the limbic system include the hippocampus, amygdala, olfactory tracts, fornix, cingulate gyrus, and mamillary bodies. The parahippocampal gyrus is the in-rolled medial border of the temporal lobe and resembles the shape of a seahorse when viewed in the coronal plane (Fig. 3.57). Contained within this gyrus are the hippocampus and amygdala, prominent structures involved with memory and emotion. The hippocampus is an important structure that has a strong role in the transition

116

CHAPTER 3  Brain

of short-term memory to long-term memory. The amygdala is an almond-shaped mass of gray matter located deep within the parahippocampal gyrus anterior to the hippocampus (Figs. 3.40 and 3.52–3.54). The amygdala coordinates the actions of the autonomic and endocrine systems and is concerned with decision making, emotional processing, and aggressive and sexual behavior. The olfactory tracts run underneath the frontal lobes and connect to the amygdala to bring information from the sense of smell to the limbic system (Figs. 3.52 and 3.56). The limbic system is integrated with other important structures of the brain via limbic fiber tracts. The most frequently identified limbic tract is the fornix. The fornix is an arch-shaped structure that lies below the splenium of the corpus callosum and makes up the inferior margin of the septum pellucidum. It serves specifically to integrate the hippocampus with other functional areas of the brain (Figs. 3.45, 3.46, 3.52, 3.55, and 3.57). The cingulate gyrus is a prominent gyrus located on the medial border of each cerebral hemisphere just superior to the corpus callosum (Figs. 3.52, 3.55, and 3.57). This area is considered to be the brain’s emotional control center, so it plays an important role in the limbic system.

The mamillary bodies are two small rounded bodies in the floor of the posterior hypothalamus responsible for memory and motivation. They receive direct input from the hippocampus via the fornix and give rise to fibers that terminate in the anterior thalamus and the periaqueductal gray matter of the midbrain (Figs. 3.45, 3.46, 3.52, and 3.53). Damage to the hippocampus may result in the loss of memory. High-resolution magnetic resonance images (MRIs) of the hippocampus are useful in evaluating patients with dementia or seizures associated with hippocampal sclerosis.

The amygdala is involved in learning and helps establish whether environmental cues and experiences are rewarding or dangerous. Abnormalities of the amygdala can profoundly influence behavior and have been linked to numerous neuropsychiatric and neurodevelopmental disorders. Amygdala dysregulation may cause increased risk taking, inappropriate social behavior, and elevated anxiety.

A

Lateral fissure

Optic tract

Suprasellar cistern

Mamillary body

Amygdala R

L

Ambient cistern

Hippocampus

Occipital lobe

Cerebral peduncle of midbrain Vermis of cerebellum P

FIG. 3.53  Axial, T1-weighted MRI of hippocampus and amygdala.

CHAPTER 3  Brain Suprasellar cistern

A

Lateral fissure Ambient cistern

Amygdala

L

R

Midbrain

Hippocampus

R

L P

Vermis of cerebellum

Cerebellum

FIG. 3.54  Axial CT of hippocampus and amygdala.

Cingulate gyrus Corpus callosum

Fornix

Inferior colliculi Cerebral aqueduct

Hippocampus

FIG. 3.55  Coronal view of hippocampus and fornix.

117

118

CHAPTER 3  Brain S

Frontal lobe R

L

Ethmoid sinuses

I

Olfactory tract

FIG. 3.56  Coronal, T2-weighted MRI of olfactory tracts.

Lateral ventricle

Corpus callosum

S

Fornix

Cingulate gyrus Thalamus

L

R

Temporal horn of lateral ventricle

Posterior commissure

Hippocampus Third ventricle

I

Pons

FIG. 3.57  Coronal, T2-weighted MRI of fornix, cingulate gyrus, and hippocampus.

CHAPTER 3  Brain

BRAINSTEM The brainstem is a relatively small mass of tissue packed with motor and sensory nuclei, making it vital for normal brain function. Of the 12 cranial nerves, 10 originate from nuclei located in the brainstem. Its major segments are the midbrain, pons, and medulla oblongata (Figs. 3.45, 3.46, 3.58, and 3.59). Located within the central portion of the brainstem and common to all three segments is the tegmentum, an

area that provides integrative functions, such as complex motor patterns, aspects of respiratory and cardiovascular activity, and regulation of consciousness (Fig. 3.60). The central core of the tegmentum contains the reticular formation, an area containing the cranial nerve nuclei and ascending and descending tracts to and from the brain. The brainstem as a whole acts as a conduit among the cerebral cortex, cerebellum, and spinal cord (Fig. 3.61).

Optic nerve (CN II) Optic chiasm

Thalamus

Floor of hypothalamus Optic tract Mamillary body Infundibulum (pituitary removed)

Trochlear nerve (CN IV)

Oculomotor nerve (CN III)

Trigeminal nerve (CN V)

Midbrain (cerebral peduncle)

Pons

Facial nerve (CN VII)

Middle cerebellar peduncle

Vestibulocochlear nerve (CN VIII)

Abducens nerve (CN VI)

Glossopharyngeal nerve (CN IX)

Hypoglossal nerve (CN XII) Medulla oblongata

Olive

Anterior median fissure

Vagus nerve (CN X)

Medullary pyramid

Accessory nerve (CN XI)

Decussation of pyramids Spinal cord

Ventral root of first cervical nerve

FIG. 3.58  Anterior view of brainstem and cranial nerves.

Thalamus Cerebral aqueduct Pineal gland Lateral geniculate nucleus Tectum of midbrain

Superior colliculus

Medial geniculate nucleus

Inferior colliculus

Trochlear nerve (CN IV) Superior cerebellar peduncle Inferior cerebellar peduncle

Middle cerebellar peduncle extending to pons

Facial nerve (CN VII)

Anterior wall of fourth ventricle

Vestibulocochlear nerve (CN VIII)

Choroid plexus (fourth ventricle)

Glossopharyngeal nerve (CN IX) Vagus nerve (CN X)

Posterior median fissure Medulla oblongata

119

Accessory nerve (CN XI) Posterior (dorsal) root of first cervical nerve

FIG. 3.59  Posterior view of brainstem.

120

CHAPTER 3  Brain

Midbrain

The tectum consists of four rounded protuberances termed colliculi. The upper pair, the superior colliculi, is a center for visual reflexes that coordinates movements of the eyes with those of the head and neck. The lower pair, the inferior colliculi, acts as a relay station for the auditory pathway, providing auditory information to the thalamus (Figs. 3.46 and 3.59–3.65). Anterior to the cerebral aqueduct are the two large cerebral peduncles (Figs. 3.46, 3.58, 3.60, and 3.62–3.65). These ropelike bundles, composed predominantly of axons that are a direct extension of the fibers of the internal capsule, extend from the cerebral cortex to the spinal cord

The midbrain (mesencephalon), which is located above the pons at the junction of the middle and posterior cranial fossae, is the smallest portion of the brainstem. The midbrain is primarily composed of massive bundles of nerve fiber tracts and can be divided into two major segments: cerebral peduncles and the tectum (quadrigeminal plate) (Figs. 3.58–3.60). The midbrain surrounds the cerebral aqueduct, which contains CSF and connects the third and fourth ventricles. Posterior to the cerebral aqueduct is the tectum, which makes up the roof or dorsal surface of the midbrain (Figs. 3.58–3.60).

Cerebral aqueduct Superior colliculi

Tectum

Inferior colliculi Periaqueductal gray matter

Cerebral peduncle of midbrain

Central gray matter Fourth ventricle

Tegmentum Pons

Median aperture Medulla oblongata Central canal

Spinal cord

FIG. 3.60  Sagittal view of brainstem with tegmentum.

Radiations to cerebral cortex

Pineal gland

Superior colliculi Tectum Inferior colliculi

Visual impulses

Pons

Midbrain

Medulla oblongata Reticular formation Ascending general sensory tracts (touch, pain, temperature)

Auditory impulses Descending motor projections to spinal cord

FIG. 3.61  Sagittal view of brainstem with reticular formation.

CHAPTER 3  Brain

121

S

Pineal gland Superior colliculus Inferior colliculus R

L Cerebral aqueduct Cerebral peduncle Cerebellum

I

FIG. 3.62  Coronal, T1-weighted MRI of midbrain.

Cerebral peduncle

Red nucleus

Substantia nigra

Tegmentum Tectum (colliculi)

Periaqueductal gray matter Cerebral aqueduct

FIG. 3.63  Axial view of midbrain and cerebral peduncles.

Tectum

CHAPTER 3  Brain

122

A

Middle cerebral artery Optic tract Cerebral peduncle R

P

Substantia nigra

Red nucleus Periaqueductal gray matter

Quadrigeminal cistern

Tectum (colliculi)

P

FIG. 3.64  Axial, proton density–weighted MRI of cerebral peduncles and red nucleus.

A Cerebral peduncle Tectum (colliculi) Lateral fissure

Third ventricle R

L

Cerebellum

Quadrigeminal cistern P

FIG. 3.65  Axial CT of cerebral peduncles and tectum.

CHAPTER 3  Brain (Figs. 3.46, 3.60, and 3.63–3.65). The cerebral peduncles are made more noticeable by the presence of the darkly pigmented substantia nigra, a broad layer of cells that contain melanin (Figs. 3.63 and 3.64). The substantia nigra is involved with the production of dopamine, a neurotransmitter in the brain that functions in facilitating movement and controlling the brain’s reward system. Within the tegmentum of the midbrain, at the level of the superior colliculi, is the red nucleus. The red nucleus is composed of a tract of motor nerve fibers and serves as a relay station between the cerebellum and the cerebral hemispheres (Figs. 3.63 and 3.64). The red nucleus contributes to the coordination of movements and the sense of balance. Another portion of the tegmentum is the periaqueductal gray matter, which surrounds the cerebral aqueduct. This area receives sensory input that conveys pain and temperature information to the brain (Figs. 3.60, 3.63, and 3.64). Parkinson disease, a neurodegenerative condition causing tremor and motor impairment, is caused by a loss of dopamine-secreting neurons in an area of the midbrain called the substantia nigra.

123

Dopamine is a neurotransmitter that plays a major role in reward and motivation behavior. Most rewards (e.g., food, sex, drugs of abuse, etc.) are capable of stimulating the release of dopamine in the brain. Dopamine may help with depression as well as focus/motivation; thus when dopamine levels are either elevated or low, resulting difficulties in focusing and staying on task can occur.

Pons The pons is a large, oval-shaped expansion of the brainstem centrally located between the midbrain and medulla oblongata. The pons creates a prominent bulge as it lies just posterior to the clivus and anterior to the cerebellum. The term pons literally means “bridge.” This definition is appropriate because the pontine fibers relay signals between the spinal cord and the cerebral and cerebellar cortices (Figs. 3.46, 3.58, 3.60, 3.61, and 3.66–3.69).

A

Lateral fissure

Basilar artery Hippocampus

Temporal horn of lateral ventricle

Pons R

L

Fourth ventricle

Middle cerebellar peduncle

Cerebellum

P

FIG. 3.66  Axial CT of pons.

124

CHAPTER 3  Brain Corpus callosum S

Fornix Third ventricle Thalamus

Insula L

R Cerebral peduncle

Hippocampus Pons

Trigeminal nerve (CN V)

I

FIG. 3.67  Coronal, T1-weighted MRI of pons.

A

Pituitary gland Internal carotid artery

Basilar artery R

L Pons

Prepontine cistern Fourth ventricle Cerebellum

P

FIG. 3.68  Axial, T1-weighted MRI of pons and cerebellum.

CHAPTER 3  Brain Thalamus

S

125

Midbrain

Lateral ventricle

Tectum (colliculi)

A

P Tentorium cerebelli

Pituitary gland Pons

Sphenoid sinus

I Clivus Medulla oblongata

Fourth ventricle

Cerebellum

FIG. 3.69  Sagittal CT reformat of pons.

Medulla Oblongata The medulla oblongata extends from the pons to the foramen magnum, where it continues as the spinal cord (Figs. 3.45 and 3.46). The medulla oblongata contains all fiber tracts between the brain and spinal cord, as well as vital centers that regulate internal activities of the body. These centers are involved in the control of heart rate, respiratory rhythm, and blood pressure. The center of the anterior and posterior surfaces of the medulla oblongata is marked by the anterior and posterior median fissures (Figs. 3.58 and 3.59). These two fissures divide the medulla oblongata into two symmetric halves. Located on

either side of the anterior median fissure are two bundles of nerve fibers called medullary pyramids (Figs. 3.58, 3.70, and 3.71). The pyramids contain nerve tracts that contribute to voluntary motor control. At the lower end of the pyramids, some of the nerve tracts cross over (decussate) to the opposite side (Fig. 3.58). This decussation in part accounts for the fact that each half of the brain controls the opposite half of the body. On each lateral surface of the medulla oblongata is a rounded oval prominence called the olive. The olives consist of nuclei that are involved in coordination, balance, and modulation of sound impulses from the inner ear (Figs. 3.58 and 3.70–3.72).

Olive

A

Anterior Clivus median fissure

Medullary pyramid

L

R

Inferior cerebellar peduncle Medulla oblongata

Fourth ventricle

Vermis

P

Posterior median fissure

FIG. 3.70  Axial, T2-weighted MRI of medulla oblongata and olives.

126

CHAPTER 3  Brain Anterior median fissure

A

Medullary pyramid

Medulla oblongata

R

L

Olive

P

Inferior cerebellar peduncle

Fourth ventricle

Cerebellum

FIG. 3.71  Axial CT of medulla oblongata and olives.

S

Pineal gland Superior colliculus Inferior colliculus Cerebral peduncle

Cerebral aqueduct L

R Cerebellum Medulla oblongata

Olive

I

FIG. 3.72  Coronal, T1-weighted MRI of medulla oblongata and olives.

Tectum

CHAPTER 3  Brain

CEREBELLUM The cerebellum, which is referred to as the “little brain,” attaches posteriorly to the brainstem and occupies the posterior cranial fossa (Fig. 3.73). The cerebellum is the coordination center for motor functions. Although the cerebellum does not initiate actual motor functions, it uses the brainstem to connect with the cerebrum to execute a variety of movements, including maintenance of muscle tone, posture, balance, and coordination of movement. The cerebellum consists of two cerebellar hemispheres. These hemispheres have an interesting appearance because the folds of gray matter resemble cauliflower. A midline structure called the vermis connects the two cerebellar hemispheres

Tectum

Primary fissure

Cerebellum

127

(Figs. 3.53, 3.54, 3.73, and 3.74). On the inferior surface of the cerebellar hemispheres are two rounded prominences called the cerebellar tonsils (Figs. 3.75 and 3.76). Three pairs of nerve fiber tracts, the cerebellar peduncles, connect the cerebellum to the brainstem (Fig. 3.59). The superior cerebellar peduncles connect the cerebellum to the midbrain. The middle cerebellar peduncles serve as attachments to the pons, and the inferior cerebellar peduncles attach to the medulla oblongata (Figs. 3.74 and 3.77–3.79). All information traveling to and from the cerebellum is routed through the cerebellar peduncles. Deep within the center of each cerebellar hemisphere is a collection of nuclei called the dentate nucleus, the largest and most lateral of the deep cerebellar nuclei (Figs. 3.73, 3.74, and 3.76). Fibers of the dentate nucleus project to the thalamus via the superior cerebellar peduncles. From there, the fibers travel to the motor areas of the cerebral cortex, namely, the precentral gyrus, thus influencing motor control.

Midbrain

A defect involving downward displacement or herniation of the brainstem and cerebellum through the foramen magnum is termed Arnold-Chiari malformation (deformity), or tonsillar herniation.

Pons

Fourth ventricle

Pons Cerebellar tonsil

Dentate nucleus

Fourth ventricle Superior cerebellar peduncle

Dentate nucleus Plane of section

Vermis

Middle cerebellar peduncle

Vermis

FIG. 3.74  Axial view through cerebellum.

Dentate nucleus

FIG. 3.73  Midsagittal view of cerebellum and superior

cerebellar peduncle.

128

CHAPTER 3  Brain

Fornix

Thalamus

Mamillary body

S

Tectum (colliculi) Tentorium cerebelli Cerebral peduncle Cerebellum A

P Fourth ventricle Medulla oblongata Cerebellar tonsil

Pituitary gland

Anterior lobe

Pons

I

Posterior lobe

FIG. 3.75  Sagittal, T1-weighted MRI of cerebellum.

S Longitudinal fissure

Occipital horn of lateral ventricle L

R Tentorium cerebelli

Vermis

Dentate nucleus Cerebellum Cerebellar tonsil I

FIG. 3.76  Coronal, T1-weighted MRI of cerebellum and dentate nucleus.

CHAPTER 3  Brain

Meckel’s cave

Fourth ventricle

Pons

Cerebellopontine angle cistern

Pons

129

Middle cerebellar peduncles

A

L

R

Superior cerebellar peduncles

Cerebellum

FIG. 3.77  Axial, T2-weighted MRI of superior cerebellar peduncles.

Fourth ventricle

P

Vermis

Cerebellum

FIG. 3.78  Axial, T2-weighted MRI of middle cerebellar peduncles.

130

CHAPTER 3  Brain tissues. However, there are some structures located within the brain that do not have a BBB, so they will naturally enhance when contrast media is used. It is normal for the pituitary gland, infundibulum, pineal gland, choroid plexus, mucosal surfaces of the nasopharynx and sinuses, venous structures, and meninges to be enhanced to varying degrees after contrast administration.

Arterial Supply A

The brain receives arterial blood from two main pairs of vessels and their branches, the internal carotid arteries and the vertebral arteries, which make up the anterior and posterior circulation, respectively (Figs. 3.80 and 3.92A). Many normal variations of the arterial blood supply exist. This section focuses on the most common anatomic findings visualized in cross-section (Figs. 3.80–3.103).

Medullary Inferior cerebellar peduncle pyramid

Internal Carotid Arteries.  The internal carotid ar-

R

L

P

Cerebellum

FIG. 3.79  Axial, T2-weighted MRI of inferior cerebellar peduncles.

CEREBRAL VASCULAR SYSTEM The vascular supply to the brain is unique. In comparison with the arteries in the body, the walls of the arteries in the brain are thin and weak, causing them to be susceptible to aneurysms and strokes. The veins of the brain do not contain valves. This lack of valves allows the blood to flow in either direction, creating a route for blood-borne pathogens to pass from the body to the head and vice versa. The capillaries of the brain are unlike those elsewhere in the body in that they do not allow movement of certain molecules from their vascular compartment into the surrounding brain tissue. This unique quality of impermeability is termed the blood–brain barrier (BBB). The presence of a normal BBB prevents large amounts of contrast medium from entering the brain. Pathologic conditions can disrupt the integrity of the BBB, allowing contrast to escape from the vessel into the surrounding

teries supply the frontal, parietal, and temporal lobes of the brain and orbital structures. These arteries arise from the bifurcation of the carotid arteries in the neck and can be divided into seven segments (Table 3.1 and Figs. 3.85 and 3.86). They ascend through the base of the skull and enter the carotid canals of the temporal bones (Figs. 3.80, 3.82, and 3.83). The internal carotid artery (ICA) then turns forward within the cavernous sinus, then up and backward through the dura mater, forming an S shape (which is referred to as the carotid siphon) before it reaches the base of the brain (Figs. 3.80 and 3.85– 3.87). As the ICA exits the cavernous sinus, it branches into the ophthalmic artery just inferior to the anterior clinoid process (Figs. 3.80 and 3.85). The ICA then runs lateral to the optic chiasm and branches into the anterior cerebral artery and the larger middle cerebral artery (Tables 3.1 and 3.2 and Figs. 3.80, 3.81, and 3.84–3.88). The anterior cerebral artery and its branches supply the anterior frontal lobe and the medial aspect of the parietal lobe (Fig. 3.84). The main segments and branches of the anterior cerebral artery are the horizontal (A1) segment, the vertical (A2) segment, and the distal (A3) segment (Figs. 3.84–3.88). The horizontal segment extends from the ICA bifurcation to the anterior communicating artery. The anterior communicating artery joins the two anterior cerebral arteries just anterior to the optic chiasm (Figs. 3.87–3.89). The vertical segment, an extension of the horizontal segment, courses superiorly toward the rostrum of the corpus callosum. The major branches of the vertical segment are the orbitofrontal, frontopolar, callosomarginal, and splenial arteries (Figs. 3.84 and 3.85). The distal segment curves around the genu of the corpus callosum and continues as the pericallosal artery (Tables 3.1 and 3.2 and Figs. 3.80 and 3.84) The middle cerebral artery is by far the largest of the cerebral arteries and is considered a direct continuation of the internal carotid artery. The middle cerebral artery gives off many branches as it supplies much of the lateral

CHAPTER 3  Brain TABLE 3.1

131

Segments of Internal Carotid, Anterior Cerebral, and Middle Cerebral Arteries

Artery

Segments

Location

Internal carotid artery (ICA)

Cervical (C1) Petrous (C2) Lacerum (C3) Cavernous (C4) Clinoid (C5)

Bifurcation of common carotid artery to carotid canal of temporal bone Carotid canal to foramen lacerum within the petrous portion of temporal bone Extends above foramen lacerum to curve toward cavernous sinus Cavernous sinus Exits the cavernous sinus to enter the subarachnoid space near the anterior clinoid process of sphenoid bone Extends from clinoid segment to the origin of the posterior communicating artery (PCoA) Origin of the PCoA to the bifurcation of the ICA into the anterior and middle cerebral arteries Termination of ICA to junction with anterior communicating artery (ACoA) From junction with ACoA, superiorly through longitudinal fissure, to origin or callosomarginal artery Continues from callosomarginal artery origin as pericallosal artery ICA bifurcation to lateral fissure Courses superiorly within the lateral fissure to the insula Courses inferolaterally through lateral fissure Exits lateral fissure to cortex

Ophthalmic (supraclinoid) (C6) Communicating (terminal) (C7) Anterior cerebral artery (ACA) Middle cerebral artery (MCA)

Horizontal (precommunicating) (A1) Vertical (postcommunicating) (A2) Distal (A3) Horizontal (M1) Insular (M2) Opercular (M3) Cortical (M4)

Middle cerebral artery

Posterior communicating artery

Pericallosal artery

Posterior cerebral artery Anterior cerebral artery

Basilar artery

Ophthalmic artery

Carotid siphon

Anterior inferior cerebellar artery Internal carotid artery Posterior inferior cerebellar artery

External carotid artery

Vertebral artery

FIG. 3.80  Lateral view of cerebral arterial system.

132

CHAPTER 3  Brain

Head of caudate nucleus Internal capsule

Cortical M4 segment Claustrum

External capsule

Opercular M3 segment

Lateral fissure

Lentiform nucleus Extreme capsule

Insular M2 segment

Anterior cerebral artery

Insula Lenticulostriate arteries

Middle cerebral artery Cavernous sinus Internal carotid artery

Temporal lobe Optic chiasm

Horizontal M1 segment

Pituitary gland

FIG. 3.81  Coronal view of internal carotid and middle cerebral arteries.

A

Internal carotid artery coursing in the carotid canal

L

R

Basilar artery Pons

P

FIG. 3.82  Axial, proton density–weighted MRI with carotid canal.

CHAPTER 3  Brain

133

A

Sphenoid sinus Internal carotid artery within carotid canal of temporal bone

Middle ear Inner ear L

R EAM

IAC

Basilar artery

P

FIG. 3.83  Axial CT with carotid canal.

Pericallosal artery

Callosomarginal artery

Parieto-occipital artery Calcarine artery

Anterior cerebral artery (distal A3 segment)

Frontopolar artery Anterior cerebral artery (vertical A2 segment) Orbitofrontal artery Anterior cerebral artery (horizontal A1 segment)

Superior cerebellar artery

Posterior cerebral artery

Anterior inferior cerebellar artery

Pons Basilar artery

FIG. 3.84  Sagittal view of anterior cerebral artery and branches.

Posterior inferior cerebellar artery

CHAPTER 3  Brain

134

TABLE 3.2

Internal Carotid Artery Branches

Artery

Region Supplied

Ophthalmic artery Anterior cerebral artery (ACA)

Globe, orbit, frontal scalp, and frontal and ethmoid sinuses Anterior frontal lobe and medial aspect of parietal lobe, head of caudate nucleus, anterior limb of the internal capsule, and anterior globus pallidus Lateral surface of the cerebrum, insula, anterior and lateral aspects of temporal lobe, nearly all the basal nuclei, and posterior and anterior internal capsules

Middle cerebral artery (MCA)

Pericallosal artery Callosomarginal artery

Anterior cerebral artery (distal A3 segment) S

Middle cerebral artery Internal carotid artery (communicating C7 segment)

Anterior cerebral arteries (vertical A2 segment)

Posterior cerebral arteries

Ophthalmic artery Internal carotid artery (ophthalmic C6 segment)

Basilar artery A

P

Internal carotid artery (clinoid C5 segment) Carotid siphon Internal carotid artery (cavernous C4 segment)

Vertebral arteries

Internal carotid artery (lacerum C3 segment)

Internal carotid artery (petrous C2 segment)

I Internal carotid artery (cervical C1 segment)

FIG. 3.85  Lateral CTA of cerebral arteries. surface of the cerebrum, insula, and anterior and lateral aspects of the temporal lobe; nearly all the basal nuclei; and the posterior and anterior internal capsule (Figs. 3.80 and 3.81). The four major segments of the middle cerebral artery are the horizontal (M1), insular (M2), opercular (M3), and cortical (M4) (Tables 3.1 and 3.2 and Figs. 3.81 and 3.85–3.91). The horizontal segment courses from the origin at the ICA bifurcation laterally toward the insula and branches into the lateral lenticulostriate arteries, which supply to the lentiform nucleus, parts of the internal capsule, and caudate nucleus (Fig. 3.81). The insular segment courses along the insula, continuing as the opercular segment that emerges from

the lateral fissure. Upon exiting the lateral fissure, the opercular segment becomes the cortical segment, which splits into the superior and inferior groups of cortical branches that supply nearly the entire surface of the cerebral hemispheres. A lacunar stroke or infarct is caused by occlusion of an artery that supplies the deep structures of the brain, such as the basal nuclei and internal capsule. The lenticulostriate branches of the middle cerebral artery supply blood to this area. Occlusion of one of these vessels will result in a lacunar infarct, causing this area to be the most frequent site of strokes.

CHAPTER 3  Brain Internal carotid artery (communicating C7 segment)

Posterior cerebral artery

Superior cerebellar artery

Anterior cerebral artery (vertical A2 segment) Middle cerebral artery Internal carotid artery (ophthalmic C6 segment) Basilar artery Internal carotid artery (clinoid C5 segment)

Posterior inferior cerebellar artery

Internal carotid artery (cavernous C4 segment)

Vertebral arteries

Carotid siphon

Internal carotid artery (lacerum C3 segment) Internal carotid artery (cervical C1 segment)

Internal carotid artery (petrous C2 segment)

FIG. 3.86  Lateral MRA of cerebral arteries.

Internal Anterior cerebral carotid artery arteries (vertical (carotid siphon) A2 segment)

A

Anterior communicating artery

Middle cerebral artery (horizontal M1 segment)

Middle cerebral artery (insular M2 segment) Middle cerebral artery (opercular M3 segment) Anterior cerebral artery (horizontal A1 segment)

Basilar artery Middle cerebral artery (cortical M4 segment)

P Vertebral arteries

FIG. 3.87  Submentovertex CTA of internal carotid arteries.

135

136

CHAPTER 3  Brain Anterior Anterior cerebral Middle cerebral Anterior cerebral artery (horizontal artery (horizontal communicating arteries (vertical artery A2 segment) M1 segment) A1 segment) S

Carotid siphon R

L Internal carotid artery

I

FIG. 3.88  Coronal oblique MRA of anterior cerebral arteries.

Anterior cerebral artery A Middle cerebral artery (horizontal M1 segment)

Anterior communicating artery

Posterior cerebral artery (ambient P2 segment)

Suprasellar cistern

Cerebral aqueduct

Cerebral peduncle L

R

Tectum

P

FIG. 3.89  Axial, T2-weighted MRI with anterior communicating and middle cerebral arteries.

Quadrigeminal cistern

CHAPTER 3  Brain Middle cerebral artery (MCA) (horizontal M1 segment)

ICA bifurcation

137

Anterior cerebral artery

A

Cerebral peduncle

MCA bifurcation

MCA (Insular M2 segment)

R

L Tectum

Posterior communicating artery

Posterior cerebral artery

P Basilar artery bifurcation

FIG. 3.90  Axial CT with middle cerebral artery.

Anterior cerebral arteries

Middle cerebral artery S (horizontal M1 segment)

Middle cerebral artery (opercular M3 segments)

Middle cerebral artery (cortical M4 segments)

Middle cerebral artery (insular M2 segments) R

L

Internal carotid artery

I

FIG. 3.91  Anterior MRA of middle cerebral arteries.

138

TABLE 3.3

CHAPTER 3  Brain Segments of Vertebral and Posterior Cerebral Arteries

Artery

Segment

Location

Vertebral artery (VA)

Extraosseous (V1) Foraminal (V2) Extraspinal (V3) Intradural (V4)

Posterior cerebral artery (PCA)

Precommunicating (P1) Ambient (P2) Quadrigeminal (P3) Calcarine (P4)

Subclavian artery to C6 C6 to C1 C1 to foramen magnum Courses superomedially behind clivus, joins with contralateral VA to form basilar artery Extends from basilar artery bifurcation to posterior communicating artery Around cerebral peduncle within ambient cistern Quadrigeminal cistern In calcarine fissure on medial aspect of occipital lobe

Vertebral Arteries.  The vertebral arteries begin in

the neck at the subclavian artery and ascend vertically through the transverse foramina of the cervical spine. They can be divided into four segments (see Table 3.3). The vertebral arteries curve around the atlantooccipital joints to enter the cranium through the foramen magnum (Fig. 3.92). The two vertebral arteries course along the medulla oblongata and unite ventral to the pons, forming the basilar artery (Figs. 3.80, 3.82–3.87, and 3.92–3.100). The vertebral and basilar arteries give rise to several pairs of smaller arteries that supply the cerebellum, pons, and inferior and medial surfaces of the temporal and occipital lobes. The four major pairs of arteries are listed in order from inferior to superior: posterior inferior cerebellar (PICA), anterior inferior cerebellar (AICA), superior cerebellar (SCA), and posterior cerebral (PCA). Located between the anterior inferior cerebellar artery and superior cerebellar artery are many tiny perforating pontine vessels (Figs. 3.92B and 3.94– 3.97). The posterior cerebral arteries can be divided into four major segments: precommunicating or peduncular (P1), ambient (P2), quadrigeminal (P3), and calcarine (P4) (Fig. 3.94). The precommunicating segment is a short segment that extends laterally from the basilar bifurcation to the posterior communicating artery (Fig. 3.92C). The posterior communicating artery forms a connection between the posterior cerebral artery and the ICA (Figs. 3.92A and C, 3.94, 3.99, and 3.100). The ambient segment courses posteriorly in the ambient cistern around the midbrain and then continues as the quadrigeminal segment located within the quadrigeminal cistern. The calcarine segment is located on the medial surface of the occipital lobe. The distal posterior

cerebral artery frequently divides into many branches, including several temporal and occipital arteries (Tables 3.3 and 3.4 and Figs. 3.94, 3.101, and 3.102). Arteriovenous malformations (AVMs) are the most common type of congenital vascular malformation. They consist of a tangle of dilated arteries and veins, usually accompanied by arteriovenous shunting. Approximately 40% of individuals with AVMs will bleed by the age of 40 years.

Pathology involving the cerebrovascular system is a common cause of cranial neurologic deficits. The brain needs a constant source of oxygen and glucose and is dependent on the vascular system to provide a steady supply. Any injury or disease affecting the cerebrovascular system can result in vascular insufficiency. Vascular interruptions lasting more than a few minutes will result in necrosis of adjacent brain tissue.

Circle of Willis.  The cerebral arterial circle, or circle

of Willis, is a critically important anastomosis among the four major arteries (two vertebral and two internal carotid) feeding the brain. The circle of Willis is formed by the anterior and posterior cerebral, anterior and posterior communicating, and the internal carotid arteries. The circle is located mainly in the suprasellar cistern at the base of the brain. Many normal variations of this circle may occur in individuals. The circle of Willis functions as a means of collateral blood flow between cerebral hemispheres in the event of blockage (Figs. 3.94 and 3.98–3.103).

CHAPTER 3  Brain

139

Anterior circulation: Middle cerebral artery Posterior circulation:

Anterior cerebral artery Posterior communicating artery

Posterior cerebral artery

Ophthalmic artery

Basilar artery Ophthalmic (C6) segment Internal carotid artery

Vertebral artery, intracranial

Cavernous (C4) segment Petrous (C2) segment

Vertebral artery, extracranial

Cervical (C1) segment

External carotid artery

Subclavian artery

Internal carotid artery Common carotid artery Brachiocephalic artery Aorta

A Thalamus

Midbrain Posterior cerebral artery (PCA) Pons Cerebellum

Optic tract

Posterior communicating artery (PCoA) Superior cerebellar artery (SCA) Short and long circumferential pontine arteries Basilar artery Internal auditory (labyrinthine) artery Anterior inferior cerebellar artery (AICA)

Posterior inferior cerebellar artery (PICA)

Medulla oblongata Vertebral artery

B Anterior spinal artery FIG. 3.92  Vertebrobasilar arterial system. (A) Lateral view of vertebrobasilar arterial system. (B) Lateral view of basilar artery and branches.

140

CHAPTER 3  Brain Right anterior cerebral artery Right middle cerebral artery

Anterior communicating artery Left posterior communicating artery

Right ophthalmic artery

Left posterior cerebral artery (precommunicating P1 segment)

Right posterior cerebral artery (ambient P2 segment)

Basilar artery

Right internal carotid artery

Left internal carotid artery

Right external carotid artery

Left external carotid artery

Right common carotid artery

Left common carotid artery

Right vertebral artery

Left vertebral artery

Right subclavian artery Left subclavian artery Brachiocephalic trunk

Aortic arch

C

FIG. 3.92, cont’d  (C) Anterior view of internal carotid and vertebral arteries.

Right vertebral artery

A

Basilar artery

Left vertebral artery

L

R

P

FIG. 3.93  Axial CT of vertebral and basilar arteries.

CHAPTER 3  Brain

141

Olfactory bulb Olfactory tract

Anterior cerebral artery Anterior communicating artery

Optic nerve

Pituitary gland

Optic chiasm Posterior communicating artery

Striate arteries Middle cerebral artery

Mamillary body Posterior cerebral artery (precommunicating P1 segment)

Anterior choroidal artery

Superior cerebellar artery

Posterior cerebral artery (ambient P2 segment) Anterior inferior cerebellar artery

Basilar artery Pontine arteries

Posterior inferior cerebellar artery

Posterior cerebral artery (quadrigeminal P3 segment) Posterior cerebral artery (calcarine P4 segment) Vertebral arteries

Anterior spinal artery

FIG. 3.94  Inferior view of brain with basilar artery. S Posterior cerebral artery

Superior cerebellar artery Basilar artery R

L Anterior inferior cerebellar artery

Posterior inferior cerebellar artery

Vertebral arteries

I

FIG. 3.95  Coronal oblique MRA of vertebral and basilar arteries.

142

CHAPTER 3  Brain S

Posterior cerebral artery

Superior cerebellar artery

Basilar artery

R

L

Posterior inferior cerebellar artery

Vertebral artery

I

FIG. 3.96  Anterior CTA of vertebral and basilar arteries. S

Posterior cerebral artery Superior cerebellar artery Pontine artery

Anterior inferior cerebellar artery R

L

Basilar artery

Occipital condyle

Vertebral artery C1 Internal carotid artery (cervical C1 segment)

C2

I

FIG. 3.97  Coronal CT reformat of vertebral and basilar arteries.

CHAPTER 3  Brain Anterior communicating artery Anterior cerebral artery Middle cerebral artery

Internal carotid artery Basilar artery

Posterior cerebral artery

Vertebral arteries

FIG. 3.98  Anterior CTA of circle of Willis.

Internal carotid artery

A

MCA bifurcation Anterior cerebral artery (ACA)

Insular (M2) segments

Basilar artery bifurcation

R

L

Middle cerebral artery (horizontal M1 segment)

Posterior cerebral artery (ambient P2 segment)

Posterior communicating artery (PCoA) Posterior cerebral artery (precommunicating P1 segment)

P

FIG. 3.99  Axial CT with posterior communicating artery.

143

144

CHAPTER 3  Brain Anterior cerebral artery Left posterior communicating artery Anterior communicating artery Basilar artery

Right middle cerebral artery

Left internal carotid artery

Right posterior cerebral artery

Left vertebral artery

Superior cerebellar artery

FIG. 3.100  Submentovertex MRA of circle of Willis.

Posterior cerebral artery (ambient P2 segment)

A

Midbrain

Posterior cerebral artery (precommunicating P1 segment)

Middle cerebral artery (horizontal M1 segment)

Suprasellar cistern Interpeduncular cistern L

R

Ambient cistern

Quadrigeminal cistern P

FIG. 3.101  Axial, T2-weighted MRI of middle and posterior cerebral arteries.

CHAPTER 3  Brain A

Right anterior cerebral artery Basilar artery bifurcation

Middle cerebral artery R

L

Posterior cerebral artery (ambient P2 segment)

Midbrain

Posterior cerebral artery (precommunicating P1 segment)

P

FIG. 3.102  Axial CT of posterior cerebral arteries.

TABLE 3.4

Vertebral and Basilar Artery Branches

Artery

Region Supplied

Posterior inferior cerebellar (PICA) Anterior inferior cerebellar (AICA) Pontine vessels Superior cerebellar (SCA)

Inferior cerebellum

Posterior cerebral (PCA)

Anterior and inferior cerebellum Pons Superior cerebellum, portions of midbrain, and pons Occipital and temporal lobes

Anterior communicating Anterior cerebral Internal carotid Middle cerebral Posterior communicating Posterior cerebral Superior cerebellar Pontine Basilar Internal auditory (labyrinthine) Anterior inferior cerebellar Vertebral Posterior inferior cerebellar Anterior spinal

FIG. 3.103  Inferior view of circle of Willis.

145

146

CHAPTER 3  Brain

Venous Drainage

major dural sinuses are the superior and inferior sagittal, straight, transverse, sigmoid, cavernous, and petrosal (Figs. 3.104 and 3.105). The superior sagittal sinus lies in the longitudinal fissure between the falx cerebri and the cranium. It begins at the crista galli, runs the entire length of the falx cerebri, and ends at the internal occipital protuberance of the occipital bone (Figs. 3.3 and 3.104–3.108). The inferior sagittal sinus, which is much smaller than the superior sagittal sinus, runs posteriorly just under the free edge of the falx cerebri

The venous system of the brain and its coverings are primarily composed of the dural sinuses, superficial cortical veins, and deep veins of the cerebrum.

Dural Sinuses.  The dural sinuses are very large veins located within the dura mater of the brain. All the veins of the head drain into the dural sinuses and ultimately into the internal jugular veins of the neck. The seven

Septal, choroidal and thalamostriate veins

Superior anastomotic vein

Superior sagittal sinus Inferior sagittal sinus Internal cerebral vein Great cerebral vein Basal vein of Rosenthal

Anterior cerebral vein

Straight sinus Inferior anastomotic vein

Superficial middle cerebral vein Deep middle cerebral vein Cavernous sinus Superior petrosal sinus Inferior petrosal sinus

Transverse sinus Sigmoid Occipital sinus sinus

FIG. 3.104  Lateral view of intracranial venous system. Septal vein

Choroidal vein

S

Thalamostriate Superior vein sagittal sinus

Inferior sagittal sinus Great cerebral vein P

A Internal cerebral veins

Straight sinus

Confluence of sinuses

Sigmoid sinus Internal jugular vein I

Transverse sinus

FIG. 3.105  Lateral CT venogram of cerebral venous system.

CHAPTER 3  Brain within the longitudinal fissure (Figs. 3.3, 3.104, 3.105, and 3.107). The inferior sagittal sinus converges into the great cerebral vein to form the straight sinus. The straight sinus extends along the length of the junction of the falx cerebri and the tentorium cerebelli (Figs. 3.3, 3.104, 3.105, and 3.107–3.109). The junction of the superior sagittal, transverse, and straight sinuses creates

the large confluence of sinuses or the torcular herophili (Figs. 3.3, 3.104, 3.105, 3.109, and 3.110). The transverse sinuses extend from the confluence of sinuses between the attachment of the tentorium and the cranium (Figs. 3.3 and 3.110–3.112). As the transverse sinuses pass through the tentorium cerebelli, they become the sigmoid sinuses. The S-shaped sigmoid sinuses A

Falx cerebri

R

L

P

Parietal lobe

Superior sagittal sinus

Calvaria

FIG. 3.106  Axial CT with superior sagittal sinus.

Superior sagittal sinus

147

Internal cerebral vein

S

Interior Great sagittal cerebral vein Straight sinus (vein of Galen) sinus

A

P Internal occipital protuberance

I

FIG. 3.107  Sagittal CT reformat of inferior sagittal and straight sinuses.

148

CHAPTER 3  Brain S Superior sagittal sinus Internal cerebral vein Great cerebral vein Straight sinus

A P

Internal occipital protuberance

Anterior cerebral artery

I

FIG. 3.108  Midsagittal, T2-weighted MRI with internal cerebral vein. Lateral ventricle A

Great cerebral vein

L

R Calcified choroid plexus

P

FIG. 3.109  Axial CT of straight sinus.

Confluence of sinuses

Straight sinus

CHAPTER 3  Brain Superior sagittal sinus

FIG. 3.110  Coronal MRI with transverse and sigmoid sinuses.

Right transverse sinus

Confluence of sinuses

Left sigmoid sinus

A

Lateral fissure

R

L Temporal lobe

Right transverse sinus

P

FIG. 3.111  Axial CT of transverse sinuses.

Left transverse sinus

149

150

CHAPTER 3  Brain Internal carotid artery leaving cavernous sinus

Optic nerve (CN II)

Meningeal branches of trigeminal nerve (CN V) V3 V2

Superior ophthalmic vein Ophthalmic artery

Pituitary gland

V1

Foramen rotundum Cavernous sinus

Middle meningeal vessels

Anterior clinoid process Foramen ovale

Abducens nerve (CN VI)

Trigeminal nerve (CN V)

Oculomotor nerve (CN III)

Petrosal sinuses Sigmoid sinus Pons

Midbrain Trochlear nerve (CN IV) Cerebellum

Great cerebral vein

Tentorium cerebelli Straight sinus

Transverse sinus Confluence of sinuses

FIG. 3.112  Axial view of dural sinuses.

Optic nerve (CN II)

Free edge of tentorium cerebelli

Pituitary gland

Subarachnoid space Oculomotor nerve (CN III)

Cavernous sinus

Trochlear nerve (CN IV) Dura Ophthalmic branch of trigeminal nerve (CN V1)

Sphenoid sinus

Maxillary branch of trigeminal nerve (CN V2) Greater wing of sphenoid bone

Abducens nerve (CN VI) Internal carotid artery

Sympathetic fibers

FIG. 3.113  Coronal view of cavernous sinus.

CHAPTER 3  Brain

151

Sphenoid sinus

A

Cavernous sinus L

R

Internal carotid artery

P

FIG. 3.114  Axial, T1-weighted MRI of cavernous sinus with contrast enhancement.

Cavernous sinus

A

Pituitary gland

R

L

FIG. 3.115  Axial CT of cavP

Dorsum sella

ernous sinus with contrast enhancement.

152

CHAPTER 3  Brain

S

Cavernous sinus

Internal carotid artery Trochlear nerve (CN IV) Oculomotor nerve (CN III)

Trigeminal nerve (ophthalmic division) (CN V1) L

R Abducens nerve (CN VI)

Sphenoid sinus

Trigeminal nerve maxillary division (CN V2)

I

FIG. 3.116  Coronal, T1-weighted MRI of cavernous sinus with contrast enhancement.

S

Pituitary gland R

L P

Cavernous sinus

I

FIG. 3.117  Coronal CT reformat of cavernous sinus with contrast enhancement.

Sphenoid sinus

CHAPTER 3  Brain continue in the posterior cranial fossa to join the jugular bulbs of the internal jugular veins (Figs. 3.104, 3.105, 3.110, and 3.112). The cavernous sinuses, located on each side of the sella turcica and body of the sphenoid bone, are formed by numerous interconnected venous channels. They envelop the internal carotid arteries and third through sixth cranial nerves. Each cavernous sinus receives blood from the superior and inferior ophthalmic veins and communicates with the transverse sinuses via the petrosal sinuses (Figs. 3.104, 3.112, and 3.113–3.117).

Superficial Cortical and Deep Veins.  The superficial cortical veins are located along the surface of each cerebral hemisphere and are responsible for draining the cerebral cortex and portions of the white matter. The veins drain into the dural sinuses with numerous anastomoses between the superficial and deep veins (Fig. 3.118). The deep veins of the cerebrum drain the white matter and include the thalamostriate, septal, internal cerebral, basal (vein of Rosenthal), and great cerebral vein Superficial cortical veins

153

(vein of Galen) (Figs. 3.104–3.123). The thalamostriate vein runs in a groove between the thalamus and caudate nucleus, where it drains both structures. The septal vein runs posteriorly across the septum pellucidum and joins with the thalamostriate veins to create the paired internal cerebral veins at the inferior aspect of the interventricular foramen (Figs. 3.104, 3.105, and 3.122). The basal vein of Rosenthal drains the medial temporal lobe and basal nuclei as it curves posteriorly around the cerebral peduncle and quadrigeminal plate to join the great cerebral vein. Each internal cerebral vein runs posteriorly beneath the third ventricle to meet with the paired basal veins beneath the corpus callosum to form a short trunk, the great cerebral vein. The unpaired great cerebral vein (vein of Galen) is a short, midline vessel running between the splenium of the corpus callosum and pineal gland, where it joins with the inferior sagittal sinus to form the straight sinus. All cerebral venous output will eventually drain into one of the dural sinuses and ultimately into the internal jugular veins (Figs. 3.104, 3.105, 3.107–3.109, and 3.118–3.123).

Superior sagittal sinus

Corpus callosum Head of caudate nucleus

Superficial middle cerebral vein

Transverse sinus Sigmoid sinus

Fornix Thalamostriate vein Choroidal vein

Internal jugular vein

FIG. 3.118  Lateral view of superficial cortical veins.

Third ventricle

Thalamus Internal cerebral vein Pineal gland Great cerebral vein Basal vein of Rosenthal

Straight sinus Entry point of inferior sagittal sinus

FIG. 3.119  Superior view of deep cerebral veins.

154

CHAPTER 3  Brain A

Lateral ventricle

Third ventricle R

L

L

Basal vein of Rosenthal

Tectum Midbrain

Cerebellum

P

FIG. 3.120  Axial CT of basal vein of Rosenthal. A

Thalamostriate vein Internal cerebral vein

R

L

Great cerebral vein

Straight sinus

P

FIG. 3.121  Axial CT of internal cerebral and thalamostriate veins.

CHAPTER 3  Brain Choroidal vein

155

Thalamostriate vein Fornix

Septal vein Corpus callosum

Inferior sagittal sinus

Internal cerebral vein

Anterior cerebral vein

Straight sinus

Deep middle cerebral vein Striate veins

Basal vein (vein of Rosenthal) Superior sagittal sinus

Great cerebral vein (vein of Galen)

FIG. 3.122  Sagittal view of deep cerebral veins.

Pericallosal branch of ACA

S

Superior sagittal sinus

A

P

Straight sinus

Anterior cerebral artery (ACA)

Confluence of sinuses

I

Internal Great cerebral vein cerebral vein (vein of Galen)

FIG. 3.123  Sagittal CT reformat with deep cerebral veins.

CRANIAL NERVES There are 12 cranial nerves (CNs), numbered from anterior to posterior according to their attachment to the brain. All but the first and second CNs arise from the

brainstem (Figs. 3.58, 3.59, and 3.124). Each of these nerves corresponds to a specific function of the body (Table 3.5). It is important to recognize the adjacent brain structures that act as anatomic landmarks to localize the course of the CNs in the head.

CHAPTER 3  Brain

156

A

Olfactory bulb Optic nerve (CN II)

Olfactory nerve (CN I) Trigeminal nerve (CN V): Ophthalmic branch (V1) Maxillary branch (V2) Mandibular branch (V3)

Oculomotor nerve (CN III) Trochlear nerve (CN IV)

R

L Pons

Vestibulocochlear nerve (CN VIII)

Abducens nerve (CN VI)

Glossopharyngeal nerve (CN IX)

Facial nerve (CN VII) Hypoglossal nerve (CN XII)

Vagus nerve (CN X)

Accessory nerve (CN XI) Medulla oblongata

P

Cerebellum

FIG. 3.124  Inferior view of brain with cranial nerves. TABLE 3.5

Cranial Nerves

Cranial Nerves

Type

Olfactory (I)

Sensory Olfactory foramina in cribriform Smell plate of ethmoid bone Sensory Optic foramen Vision Motor Superior orbital fissure Movement of superior, inferior, and medial rectus; inferior oblique; and levator palpebrae muscles Motor Superior orbital fissure Movement of superior oblique muscle Mixed Meckel’s cave Sensory from face and head and movement of muscles of mastication and suprahyoid muscles Sensory Superior orbital fissure Sensation from cornea, iris, scalp, eyelids, lacrimal apparatus, nasal cavity, forehead, ethmoid and frontal sinuses, nose Sensory Foramen rotundum Sensation from upper lip, upper jaw and teeth, maxillary sinuses, palate Mixed Foramen ovale Movement of muscles of mastication and suprahyoid muscles Sensation from lower jaw and teeth, TMJ, parotid and sublingual glands, anterior 2/3 of tongue Motor Superior orbital fissure Movement of lateral rectus muscle Mixed Internal auditory canal, facial Movement of the muscles of facial expression canal, stylomastoid foramen Taste from anterior 2/3 of tongue, floor of mouth, and palate Sensation from external auditory meatus (EAM); lacrimal, parotid, sublingual, and submandibular glands

Optic (II) Oculomotor (III) Trochlear (IV) Trigeminal (V) Ophthalmic (V1) Maxillary (V2) Mandibular (V3) Abducens (VI) Facial (VII) Branches: -Temporal -Zygomatic -Buccal -Marginal mandibular -Cervical Vestibulocochlear (VIII) Vestibular branch Cochlear branch Glossopharyngeal (IX) Group 1 Group 2 Group 3 Vagus (X)

Accessory (XI) Cranial root Spinal root Hypoglossal (XII)

Foramen

Sensory Internal auditory canal Mixed

Jugular foramen

Mixed

Jugular foramen

Motor

Jugular foramen

Motor

Hypoglossal canal

Function

Sensation from vestibular structures for equilibrium Sensation from cochlea for interpretation of sound Movement of muscle for swallowing Taste from posterior 1/3 of tongue Sensory input on pain and temperature from middle ear Sensory input from carotid sinus and carotid body Movement of pharyngeal and laryngeal muscles Movement of smooth muscle in trachea, bronchi, digestive tract; moderates cardiac pacemaker and vasoconstriction of coronary arteries Sensation from EAM and dura mater of posterior cranial fossa Movement of pharynx and palate Movement of sternocleidomastoid (SCM) and trapezius muscles Movement of tongue muscles

CHAPTER 3  Brain

Olfactory Nerve (CN I) The olfactory nerve is the nerve of smell. The olfactory neurosensory cells are located in the covering of the superior nasal concha and the superior part of the nasal septum. The axons of these cells unite to form 18 to 20 small nerve bundles that are known collectively as olfactory nerve fibers. The nerve fibers pass through

the olfactory foramina in the cribriform plate of the ethmoid bone to synapse with the olfactory bulb in the anterior cranial fossa. The right and left olfactory tracts extend from the olfactory bulbs and run along the inferior surface of the frontal lobes to pass to the lateral hippocampal gyrus and interact with the limbic system (Figs. 3.124–3.127). Each olfactory nerve is surrounded by the three layers of the cranial meninges.

Olfactory bulb Frontal lobe

Frontal sinus

Olfactory tract

Cribriform plate of ethmoid bone

Superior nasal concha Middle nasal concha

Hard palate

Olfactory nerve fibers

FIG. 3.125  Sagittal view of olfactory nerve (CN I).

S

Thalamus

A

P Hypothalamus Infundibulum

Olfactory nerve (CN I)

157

Pituitary gland

I

FIG. 3.126  Sagittal, T1-weighted MRI of olfactory nerve (CN I).

CHAPTER 3  Brain

158

S

Frontal lobe R

L

Olfactory nerve

Ethmoid sinuses

I

FIG. 3.127  Coronal, T2-weighted MRI of olfactory nerve (CN I).

A

Optic nerve (CN II) R

L

Pituitary gland

P

FIG. 3.128  Axial, T1-weighted MRI of optic nerve (CN II).

Optic Nerve (CN II) The optic nerve is the nerve of sight. Sensory nerve cells arise from the retina and converge toward the posterior aspect of the eye (Figs. 3.129 and 3.130). These fibers unite to form the large optic nerve that

passes posteromedially through the optic canal into the middle cranial fossa to join its partner at the optic chiasm just anterior to the infundibulum (Figs. 3.44, 3.58, 3.128, and 3.129). In the optic chiasm, the fibers from the medial side of the retina cross to the opposite side, and the fibers from the lateral aspect remain on the same

CHAPTER 3  Brain Optic Superior rectus nerve (CN II) muscle Lens Retina

159

S

A

P

Globe

Retroorbital fat

Inferior rectus muscle

I

FIG. 3.129  Sagittal oblique CT reformat of optic nerve (CN II). Medial half of retina Lateral half of retina

Optic nerve (CN II) Optic chiasm

Optic tract

Thalamus Head of caudate nucleus

Visual cortex

A

Thalamus

Lateral geniculate body of thalamus Optic radiation

FIG. 3.130  Axial view of optic tract and optic radiations.

side (Fig. 3.130). This decussation of the medial fibers allows for binocular vision. Posterior to the optic chiasm, the optic nerve extends as optic tracts, which continue around the midbrain and terminate in the posterolateral thalamus (Figs. 3.15, 3.53, and 3.130). The optic pathway continues posteriorly from the thalamus as nerve axons forming optic radiations that are relayed to the visual cortex located in the occipital lobe (Figs. 3.130 and 3.131).

L

R

Great cerebral vein

Occipital horn of lateral ventricle

Occipital lobe

Optic radiations

P

FIG. 3.131  Axial, proton density–weighted MRI with optic

radiations.

160

CHAPTER 3  Brain

Oculomotor Nerve (CN III)

Damage to the visual system will result in visual losses related to the location of the damage. If the optic nerve is damaged anterior to the optic chiasm, the result will be loss of vision in that eye. At the optic chiasm, damage on the medial aspect will result in loss of peripheral vision, whereas damage on the lateral aspect results in loss of the ipsilateral central (nasal) visual field. If damage occurs posterior to the optic chiasm, the result will be loss of input from the contralateral visual fields of both eyes.

The oculomotor nerve moves the eye by supplying fibers to all extraocular muscles of the eye except the superior oblique and lateral rectus muscles (Figs. 3.132 and 3.133). This nerve emerges from the midbrain and passes anteriorly into the interpeduncular cistern. It runs lateral to the posterior communicating artery through the roof of the cavernous sinus and travels in the lateral wall superolateral to the ICA (Fig. 3.134). The nerve enters the orbit through the superior orbital fissure and then breaks into superior and inferior branches that innervate the superior, medial, and inferior rectus muscles, as well as the inferior oblique and levator palpebrae muscles (Figs. 3.132–3.135 and 3.137).

Superior oblique muscle Superior rectus muscle

Optic chiasm

Optic nerve (CN II)

Midbrain

Oculomotor nerve (CN III)

Trochlear nerve (CN IV)

Superior levator palpebrae muscle

Pons Inferior oblique muscle Medial rectus muscle

Abducens Inferior rectus nerve (CN VI) muscle Lateral rectus muscle (cut)

FIG. 3.132  Sagittal view of oculomotor (CN III), trochlear (CN IV), and abducens (CN VI) nerves. S

Thalamus Optic tract A

P

Oculomotor nerve (CN III)

Pons

Cerebellar tonsil

Abducens nerve (CN VI)

Vertebral artery

I

Posterior inferior cerebellar artery

FIG. 3.133  Sagittal, T2-weighted MRI with oculomotor (CN III) and abducens (CN VI) nerves.

CHAPTER 3  Brain Optic nerve (CN II) Free edge of tentorium cerebelli

Pituitary gland

Subarachnoid space Cavernous sinus

Oculomotor nerve (CN III) Trochlear nerve (CN IV)

Dura Sphenoid sinus

Ophthalmic branch of trigeminal nerve (CN V1) Maxillary branch of trigeminal nerve (CN V2)

Greater wing of sphenoid bone

Abducens nerve (CN VI)

Internal carotid artery

Sympathetic fibers

FIG. 3.134  Coronal view of cavernous sinus.

A

Pituitary gland Cavernous sinus

Basilar artery R

L Cerebral peduncle

Oculomotor nerves (CN III)

Cerebral aqueduct

Posterior cerebral artery Ambient cistern P

FIG. 3.135  Axial, T2-weighted MRI of oculomotor nerve (CN III).

161

CHAPTER 3  Brain

162

A

Basilar artery

R

L Ambient cistern

Cerebral peduncle

Fourth ventricle Trochlear nerve (CN IV)

Tectum

P

Vermis

Quadrigeminal cistern

FIG. 3.136  Axial, T2-weighted MRI of trochlear nerve (CN IV).

S Internal carotid arteries

Trochlear nerve (CN IV) Oculomotor nerve (CN III)

Trigeminal nerve (ophthalmic division) (CN V1) R

L Cavernous sinus

Abducens nerve (CN VI)

Sphenoid sinus Trigeminal nerve (maxillary division) (CN V2)

I

FIG. 3.137  Coronal, T1-weighted MRI of oculomotor (CN III) and trochlear (CN IV) nerves in cavernous sinus with contrast enhancement.

CHAPTER 3  Brain

Trochlear Nerve (CN IV)

trigeminal ganglion, where it is covered in dura, resulting in a CSF-filled subarachnoid space referred to as the trigeminal cistern (Figs. 3.138–3.141). The ophthalmic

The trochlear nerve innervates only the superior oblique muscle of the eye. It is the only cranial nerve that emerges from the posterior surface of the brainstem (Figs. 3.59, 3.132, and 3.136). The nerve originates in the tegmentum and exits the posterior surface of the midbrain. It travels around the brainstem to enter the cavernous sinus just below the oculomotor nerve. This nerve enters the orbit through the superior orbital fissure, where it finally reaches the superior oblique muscle (Figs. 3.132, 3.134, 3.136, and 3.137).

Ophthalmic branch (V1)

Trigeminal ganglion Maxillary branch (V2)

Foramen rotundum

Trigeminal Nerve (CN V) The trigeminal nerve, the largest of the cranial nerves, has three major divisions: ophthalmic, maxillary, and mandibular (Fig. 3.138). It is the major sensory nerve of the face and contains motor fibers for the muscles of mastication and sensory fibers from the head. The nerve exits the brain between the pons and the middle cerebellar peduncles (Fig. 3.58). Before trifurcating into three branches, the nerve enters Meckel’s cave and forms the

Foramen ovale Mandibular branch (V3)

FIG. 3.138  Sagittal view of trigeminal nerve (CN V).

Meckel's cave

A

Trigeminal nerve (CN V)

R

Occipital lobe

163

L

Cerebellum

P

Fourth ventricle

FIG. 3.139  Axial, T2-weighted MRI of trigeminal nerve (CN V).

Pons

CHAPTER 3  Brain

164

S

Pons L

R

Trigeminal nerve (CN V)

I

FIG. 3.140  Coronal, T1-weighted MRI of trigeminal nerve (CN V).

S

L

R

I

Trigeminal nerve (CN V)

Meckel’s cave

FIG. 3.141  Coronal CT reformat of Meckel’s cave.

branch (V1) runs through the lateral wall of the caver­ nous sinus and enters the orbit through the superior orbital fissure, where it branches again to provide sensation to the lacrimal apparatus, cornea, iris, forehead, ethmoid and frontal sinuses, and nose (Figs. 3.134 and 3.138). The maxillary branch (V2) courses in the lateral

wall of the cavernous sinus and exits the skull through the foramen rotundum (Figs. 3.134 and 3.138). Branches of the maxillary nerve continue through the inferior orbital fissure and infraorbital foramen. This branch provides sensation to the cheek, palate, sides of the nose and upper jaw and teeth, and maxillary sinuses. The

CHAPTER 3  Brain mandibular branch (V3) is considered a “motor” nerve and exits the skull through the foramen ovale. It innervates the muscles of mastication, ear canal, lower jaw and teeth, parotid and sublingual glands, and anterior two-thirds of the tongue (Figs. 3.138–3.141). Trigeminal neuralgia or tic douloureux is a neurologic syndrome involving one or more branches of the trigeminal nerve. The syndrome is characterized by sudden, severe attacks of excruciating pain which can last from a few seconds to several minutes. The painful attacks may be triggered by talking, eating, drinking, or a simple touch to the face. The most common cause is thought to be a result of compression of the nerve by an adjacent artery or vein, causing irritation. Other causes may include tumors located within the CPA cistern, trauma, infections, and multiple sclerosis.Treatment options include medication to control pain, nerve injections, and surgical or rhizotomy procedures.

Abducens Nerve (CN VI) The abducens nerve supplies motor impulses to the lateral rectus muscle of the eye. It originates near the midline of the lower portion of the pons and ascends through the prepontine cistern to the cavernous sinus. Of all the CNs within the cavernous sinus, the abducens nerve courses most medial. It exits the skull through the superior orbital fissure, where it meets up with the

165

lateral rectus muscle (Figs. 3.132–3.134, 3.137, and 3.142).

Facial Nerve (CN VII) The facial nerve emerges as two distinct roots from the lower portion of the pons in a recess between the olive and inferior cerebellar peduncle and enters the internal auditory canal of the temporal bone, just anterior to CN VIII (Figs. 3.58 and 3.143). After passing through the temporal bone, the nerve continues along the facial canal, where it finally emerges from the skull through the stylomastoid foramen and runs through the parotid gland (see Chapter 2, temporal bone). While in the parotid gland, the nerve splits into five terminal branches: temporal, zygomatic, buccal, marginal mandibular, and cervical. The facial nerve innervates the facial muscles, lacrimal gland, and parotid, sublingual, and submandibular glands. In addition, it provides taste sensation to the anterior twothirds of the tongue (Figs. 3.143 and 3.145–3.147). A type of temporary facial nerve paralysis is called Bell’s palsy. It is believed that a viral infection may cause the facial nerve to become inflamed and swell, causing the resultant paralysis. Symptoms include mild weakness, twitching, a drooping eyelid or corner of the mouth, excessive tearing, and drooling.

A

Abducens nerve (CN VI)

Temporal lobe Internal auditory canal

Meckel’s cave

R

L Basilar artery

Pons Fourth ventricle

CPA cistern

Cerebellum

P

FIG. 3.142  Axial, T2-weighted MRI of abducens nerve (CN VI).

166

CHAPTER 3  Brain Temporal branch Facial nerve (CN VII)

Zygomatic branches

Chorda tympani

Posterior auricular branch Stylomastoid foramen

Buccal branch Cervical branch

Mandibular branch

Buccal branch

FIG. 3.143  Sagittal view of facial nerve (CN VII) branches.

External ear

Middle ear

Inner ear Oval window

Auricle (pinna)

Auditory ossicles

Semicircular canals Posterior Anterior Lateral

Temporal bone (petrous portion) Vestibular complex Vestibular branch (CN VIII) Cochlea Vestibulocochlear nerve (CN VIII) Bony labyrinth of inner ear

Cartilage External auditory canal

Tympanic membrane Round Internal window jugular vein

Cochlear branch (CN VIII) Auditory tube To pharynx

FIG. 3.144  Coronal view of vestibulocochlear nerve (CN VIII) within inner ear.

CHAPTER 3  Brain S

Facial nerve (CN VII)

Cerebral peduncle

R

L

Superior semicircular canal

Pons

Vestibule

Trigeminal nerve (CN V)

Vestibulocochlear nerve (CN VIII)

Vertebral artery I

FIG. 3.145  Coronal, T2-weighted MRI of facial (CN VII) and vestibulocochlear (CN VIII) nerves.

Facial nerve (CN VII)

Pons

A

Basilar artery

Cochlea Vestibular branch Vestibulocochlear nerve (CNVIII)

Vestibule

R

L Semicircular canal

Cochlear branch

Internal auditory canal Fourth ventricle

Cerebellum P

FIG. 3.146  Axial, T2-weighted MRI of facial (CN VII) and vestibulocochlear (CN VIII) nerves.

167

CHAPTER 3  Brain

168

Glossopharyngeal nerve (CN IX)

Pons

Medulla

Vagus nerve Laryngeal nerve Vestibule

Facial nerve canal

A

Vagus nerve (CN X)

Carotid sinus

Internal auditory canal

R

L

FIG. 3.148  Glossopharyngeal (CN IX) and vagus (CN X) nerves. P

FIG. 3.147  Axial CT of internal auditory canal.

The vestibulocochlear nerve exits the brainstem at the pontomedullary junction and enters the internal auditory canal posterior to the facial nerve (Figs. 3.58 and 3.144). The vestibulocochlear nerve has two distinct components, vestibular and cochlear. The vestibular branch picks up impulses from the semicircular canals that aid in the maintenance of equilibrium. The cochlear branch receives impulses from the cochlea and separates these impulses into high and low frequencies for the interpretation of sound (Figs. 3.144–3.146).

group 2 provides sensory input on pain and temperature from the middle ear, and group 3 gathers sensory input from the carotid sinus and carotid body. The carotid sinus is a dilatation at the origin of the ICA that contains baroreceptors, which react to changes in arterial blood pressure. The carotid body, a small neurovascular structure located at the bifurcation of the common carotid artery, acts as a chemoreceptor, which senses changes in the chemical composition of blood (see Chapter 5, carotid arteries). The glossopharyngeal nerve emerges as a series of rootlets from the medulla oblongata between the olive and inferior cerebellar peduncles (Fig. 3.58). It exits the cranium through the jugular foramen and courses to the root of the tongue (Figs. 3.148–3.150).

Glossopharyngeal Nerve (CN IX)

Vagus Nerve (CN X)

The glossopharyngeal nerve supplies motor impulses to the muscles involved in swallowing. In addition, its sensory component can be divided into three groups: group 1 innervates the posterior third of the tongue,

In Latin, vagus means “wandering,” which the vagus nerve does as it “wanders” inferiorly from the brainstem to cover an extensive course as it innervates areas of the neck, thorax, and abdomen. The vagus nerve

Vestibulocochlear Nerve (CN VIII)

CHAPTER 3  Brain Dorsum sella Foramen ovale Foramen lacerum Foramen spinosum

Clivus

Hypoglossal canal

Medullary pyramid

Glossopharyngeal nerve (CN IX)

Hypoglossal nerve (CN XII) Internal auditory canal

Vagus nerve (CN X)

Medullary olive

Accessory nerve (CN XI)

Jugular fossa Jugular foramen Spinal nucleus CN V

Nucleus ambiguus

Foramen magnum

Dorsal vagal nucleus (efferent involuntary visceral motor)

Solitary tract nucleus

Fourth ventricle

Dorsal vagal nucleus (afferent visceral sensory)

FIG. 3.149  Axial view of glossopharyngeal (CN IX), vagus (CN X), and accessory (CN XI) nerves.

Olive

A

Vertebral arteries

Medullary pyramid

Jugular foramen Glossopharyngeal nerve (CN IX) R

L Medulla oblongata

Vagus nerve (CN X)

Cerebellum

P

FIG. 3.150  Axial, T2-weighted MRI of jugular foramen and glossopharyngeal (CN IX) and vagus (CN X) nerves.

169

CHAPTER 3  Brain

170

arises from the medulla oblongata as 8 to 10 rootlets between the inferior cerebellar peduncle and the olive, eventually converging into two roots that exit the skull through the jugular foramen (Fig. 3.58). It descends through the carotid sheath while in the neck and continues inferiorly to the thorax and abdomen. At the neck, it passes through the superior thoracic aperture between the subclavian artery and brachiocephalic vein, where it continues its course toward the diaphragm behind the respective main bronchi. There are many branches of the vagus nerve that supply such structures as the dura of the posterior fossa, auricle, Hypoglossal nerve (CN XII)

Pons

Medulla

Glossopharyngeal nerve (CN IX) Vagus nerve (CN X)

Tongue muscles

Accessory nerve (CN XI)

Genioglossus muscle Geniohyoid muscle

Trapezius muscle

Mylohyoid muscle Hyoid bone

Sternocleidomastoid muscle

FIG. 3.151  Sagittal view of accessory (CN XI) and hypoglossal (CN XII) nerves.

Hypoglossal nerve (CN XII)

A

external auditory meatus, pharynx, soft palate, larynx, heart, stomach, liver, duodenum, and pancreas (Figs. 3.148–3.151). The vagus nerve (CNX) provides the bulk of the parasympathetic input to the gastrointestinal system, lungs, and heart. The vagus nerve triggers the release of the neurotransmitter acetylcholine and hormones such as prolactin, vasopressin, and oxytocin that influence digestion, metabolism, and the relaxation response and may also slow the immune response. People with a stronger vagus response may recover more quickly after stress, injury, or illness.

Activation of the vagus nerve typically leads to a reduction in heart rate and/or blood pressure. This occurs commonly in the setting of gastrointestinal illness or in response to other stimuli that may include emotional stress. When the circulatory changes are great enough, vasovagal syncope results from a sudden drop in cardiac output, causing cerebral hypoperfusion.

Accessory Nerve (CN XI) The accessory nerve has both cranial and spinal roots. These two roots form a common stem before their exit through the jugular foramen. The cranial root, an accessory to the vagus nerve, emerges from a series of rootlets arising from the medulla oblongata (Fig. 3.58). These fibers supply the skeletal muscles of the pharynx and palate. The spinal root arises from a series of rootlets from the lateral cervical cord to innervate the sternomastoid and trapezius muscles in the neck and back (Figs. 3.149, 3.151, and 3.152).

Vertebral arteries

Hypoglossal canal Accessory nerve (CN XI) R

L Anterior median fissure

Olive Medulla oblongata Cerebellum

P

FIG. 3.152  Axial, T2-weighted MRI of accessory (CN XI) and hypoglossal (CN XII) nerves.

CHAPTER 3  Brain

Zygoma

Ethmoid air cells

A

Sphenoid sinus

171

Condyle of mandible

Clivus

Hypoglossal canal Temporal bone

Foramen magnum

P

Zygomatic process of temporal bone

Occipital bone

FIG. 3.153  Axial CT of occipital condyles and hypoglossal canal.

Hypoglossal Nerve (CN XII)

REFERENCES

All of the muscles of the tongue with the exception of the palatoglossus are supplied by the hypoglossal nerve. Several rootlets arise from the medulla oblongata between the olive and the medullary pyramids (Fig. 3.58). The rootlets unite to form a trunk that passes posterior to the vertebral artery to exit the cranium through the hypoglossal canal of the occipital bone (Fig. 3.149). Inferior to the skull, the hypoglossal nerve crosses lateral to the bifurcation of the common carotid artery to enter the floor of the mouth and innervate the muscles of the tongue (Figs. 3.151–3.153).

Frank, G. (2012). Merrill’s atlas of radiographic positions and radiologic procedures (12th ed.). St. Louis: Mosby. Osborn, A. G. (2016). Diagnostic imaging: Brain (3rd ed.). Philadelphia: Elsevier. Som, P. M., & Curtin, H. D. (2012). Head and neck imaging (5th ed.). St. Louis: Mosby. Standring, S. (2012). Gray’s anatomy (41st ed.). New York: Elsevier.

CHAPTER

4

Spine When you suffer an attack of nerves you’re being attacked by the nervous system. What chance has a man got against a system? Russell Hoban (1925–2011), American writer and illustrator

The spine functions to protect the delicate sensory and motor nerves that allow for peripheral sensations and body movement. Sensory or neurologic loss can be a result of injury or pathologic abnormalities of any of the many areas that constitute the normal anatomy of this region (Fig. 4.1).

FIG. 4.1  Posttraumatic fractures of the thoracic spine.

OBJECTIVES • Identify the structures of a typical vertebra. • Identify the atypical structures of the atlas and axis, thoracic vertebrae, sacrum, and coccyx. • Identify and explain the function of the spinal ligaments. • Define the action of and identify the muscle groups of the spine.

• Describe the components of the spinal cord and spinal nerves. • Describe the four plexuses of the spinal cord, and list the structures they innervate. • Identify the vasculature of the spine and spinal cord.

OUTLINE VERTEBRAL COLUMN, 173 Cervical Vertebrae, 179 Thoracic Vertebrae, 185 Lumbar Vertebrae, 185 Sacrum and Coccyx, 191 LIGAMENTS, 194 MUSCLES, 201 Superficial Layer, 202 172

Intermediate Layer, 204 Deep Layer, 205 SPINAL CORD, 210 Spinal Meninges, 210 Spinal Cord and Nerve Roots, 212 PLEXUSES, 229 Cervical Plexus, 229 Brachial Plexus, 229 Copyright © 2019, Elsevier Inc.

Lumbar Plexus, 229 Sacral Plexus, 229 VASCULATURE, 241 Spinal Arteries, 241 Spinal Veins, 246

CHAPTER 4  Spine

173

VERTEBRAL COLUMN The vertebral column is a remarkable structure that supports the weight of the body, helps maintain posture, and protects the delicate spinal cord and nerves. It is made up of 33 vertebrae, which can be separated into cervical, thoracic, lumbar, sacral, and coccygeal sections. Curvatures associated with the vertebral column provide spinal flexibility and distribute compressive forces over the spine. The cervical and lumbar sections convex forward, creating lordotic curves, and the thoracic and sacral sections convex backward, creating kyphotic curves (Fig. 4.2).

Kyphosis is a spinal disorder in which an excessive convex curvature or forward rounding of the thoracic spine occurs. In more severe situations, the kyphosis can pro­ gress over time, causing an exaggerated hunchback, which can lead to compression of the spinal cord and resulting neuro­ logic symptoms. Kyphosis can occur at any age but most commonly occurs in older women as a result of osteoporosis. Other causes of kyphosis in the elderly include degenerative arthritis and ankylosing spondylitis that can lead to a collapse of the anterior vertebral bodies. Three types of kyphosis found in children are postural kyphosis, Scheuermann’s kyphosis, and congenital kyphosis. Causes include weakening of the paraspinous muscles and ligaments, abnormal wedging of the vertebral bodies, and abnormal development of the vertebrae during development before birth.

Lordotic curve

Cervical vertebrae

Thoracic vertebrae

Kyphotic curve

Lordotic curve

Lumbar vertebrae

An abnormal lateral curvature of the spine is termed scoliosis. Scoliosis can occur from congenital bony abnormalities of the spine present at birth, growth abnor­ malities during adolescence, and degenerative spinal changes or injury that occurs during adulthood. Scoliosis is rarely painful, and small curves do not require treatment; however, larger degrees of scoliosis may require the wear­ ing of a brace or surgical interventions to restore normal posture.

Kyphotic curve Sacrum

Sacral cornu Sacral hiatus

Vertebrae vary in size and shape from section to section, but a typical vertebra consists of two main parts: the body (anterior element) and the vertebral arch (posterior element). The cylindrical body is anteriorly located and functions to support body weight (Figs. 4.3 and 4.4). The size of the vertebral bodies progressively increases from the superior to the inferior portion of the spine. The compact bone on the superior and inferior surfaces of the body is called the vertebral end plate (Figs. 4.5 and 4.6). Located posteriorly is the ringlike arch that attaches to the sides of the body, creating a space called the vertebral foramen (Figs. 4.3 and 4.4). The succession of the vertebral foramina forms the

Coccygeal cornu Coccyx

FIG. 4.2  Lateral view of the spine.

vertebral canal, which contains and protects the spinal cord. The vertebral arch is formed by pedicles (2), laminae (2), the spinous process (1), transverse processes (2), and superior (2) and inferior (2) articular processes (Figs. 4.3–4.6). The two pedicles project from the body to meet with two laminae, which continue posteriorly and medially to form a spinous process. The transverse

174

CHAPTER 4  Spine Vertebral body (anterior element)

Pedicle Vertebral foramen Superior articular process

Transverse process

Lamina

Spinous process

Vertebral arch (posterior element)

FIG. 4.3  Superior view of the typical vertebra.

Vertebral body (anterior Vertebral element) foramen A

Pedicle

Nerve roots of spinal cord (cauda equina)

R

L

Spinous process

Vertebral arch

FIG. 4.4  Axial CT of lumbar vertebra.

P

Lamina

Transverse process

CHAPTER 4  Spine Vertebral end plate

Superior costal facet Pedicle

175

Superior articular process

Body Transverse process

Vertebral end plate

Inferior costal facet

Spinous process Inferior vertebral Inferior articular notch process

FIG. 4.5  Lateral view of thoracic vertebra.

S

Pedicle Inferior vertebral notch Intervertebral foramen Superior vertebral notch Superior articular process

Vertebral body A

P

Vertebral end plates

Inferior articular process

I

FIG. 4.6  Sagittal, T2-weighted MRI of lumbar vertebrae.

176

CHAPTER 4  Spine processes project laterally from the approximate junction of the pedicle and lamina (Figs. 4.3 and 4.4). On the upper and lower surfaces of the pedicles is a concave surface termed the vertebral notch (Figs. 4.5 and 4.6). When the superior and inferior notches of adjacent vertebrae meet, they form intervertebral foramina, which allow for the transmission of spinal nerves and blood vessels (Fig. 4.6). Four articular processes, two superior and two inferior, arise from the junctions of the pedicles and laminae to articulate with adjacent vertebrae and form the zygapophyseal joints (facet joints). These joints give additional support and allow movement of the vertebral column (Figs. 4.7–4.10). The pars interarticularis is the small bony segment that joins the superior and inferior facet joints. It is the weakest portion of the vertebrae, making it the most vulnerable to injury (Figs. 4.21, 4.31, and 4.32). The vertebral bodies are separated by shock-absorbing cartilaginous intervertebral disks. These disks consist of a central mass of soft, semigelatinous material called the nucleus pulposus and a firm outer portion termed the annulus fibrosus. The nucleus pulposus contains up to 85% water at birth, which gradually decreases as a person ages. The fibers of the annulus fibrosis surround and help contain the nucleus pulposus. They attach to the anterior and posterior longitudinal ligaments, which help increase the stability of the spine (Figs. 4.9–4.12).

1 2 3 4 Facets and demi-facets on vertebral bodies

Intervertebral foramina

5

Inferior articular process

6 7

Superior articular process

8 9

Zygapophyseal joints (facet joints)

10 11 12

FIG. 4.7  Lateral oblique view of thoracic spine.

S

C1 Inferior vertebral notch Superior vertebral notch

C2 A

P Inferior articular process

C3

Superior articular process

C4

C5 C6

I

Intervertebral foramina

Zygapophyseal joints (facet joints)

FIG. 4.8  Sagittal oblique CT reformat of cervical spine with zygapophyseal joints.

CHAPTER 4  Spine

177

A Cauda equina

Annulus fibrosus Nucleus pulposus

R

L Zygapophyseal joint (facet joint)

Superior articular process Inferior articular process Spinous process

P

FIG. 4.9  Axial, T2-weighted MRI of lumbar spine with intervertebral disk and zygapophyseal joint.

Dorsal root ganglion

Annulus fibrosis

A

Nucleus pulposus

Cauda equina

R

L

Zygapophyseal joint (facet joint)

Spinous process

P

Inferior articular process

Superior articular process

FIG. 4.10  Axial CT of lumbar spine with intervertebral disk and zygapophyseal joint.

178

CHAPTER 4  Spine

Nucleus pulposus Annulus fibrosus Dorsal root ganglion

Spinal nerve

Cauda equina

Epidural space

Lamina Spinous process

FIG. 4.11  Axial view of intervertebral disk. S Spinal cord T12 Vertebral end plates L1

Annulus fibrosus of intervertebral disk

L2

A

Anterior longitudinal ligament

Posterior longitudinal ligament

P

L3

Nucleus pulposus of intervertebral disk L4

L5

I

FIG. 4.12  Sagittal, T2-weighted MRI of intervertebral disk.

CHAPTER 4  Spine

Cervical Vertebrae There are seven cervical vertebrae that vary in size and shape. The cervical vertebrae are the most mobile section of the spine. Within the transverse process of each cervical vertebra is a transverse foramen (Figs. 4.13 and 4.14). These foramina allow passage of the vertebral arteries and veins as they ascend to and descend from the head. The first cervical vertebra is termed the atlas because it supports the head; its large superior articular processes articulate with the occipital condyles of the

179

cranium to form the atlantooccipital joint. The atlas is a ringlike structure that has no body and no spinous process. It consists of an anterior arch, posterior arch, and two large lateral masses (Figs. 4.13–4.15). The lateral masses provide the only weight-bearing articulation between the cranium and vertebral column. The second cervical vertebra, the axis, has a large odontoid process (dens) that projects upward from the superior surface of the vertebral body. The odontoid process projects into the anterior vertebral foramen and articulates with the anterior arch of the atlas to act as a

Anterior arch

Transverse foramen

Superior articular process

Transverse process

Lateral mass

Posterior arch

FIG. 4.13  Superior view of C1 (atlas). Transverse Odontoid process of C2 process

A

Anterior arch

R L

Posterior arch

FIG. 4.14  Axial CT of C1 (atlas).

P

Lateral mass

Transverse foramen

180

CHAPTER 4  Spine S

Odontoid process of C2

Atlantooccipital joint

Occipital condyle

Lateral mass of C1

Superior articular process

Atlantoaxial joint

C2 R

L C3

Intervertebral disk

C4

Uncinate process

Vertebral artery

C5 C6

I

FIG. 4.15  Coronal, T1-weighted MRI of cervical spine.

pivot for rotational movement of the atlas (Figs. 4.14– 4.19). Lateral to the odontoid process on the upper surface of the body are the superior articular processes, on which the atlas articulates at the atlantoaxial joint (Figs. 4.15–4.17 and 4.19–4.21). The spinous process of the axis is the first projection to be felt in the posterior groove of the neck. The cervical vertebrae C3–C6 have a unique configuration with their bifid spinous processes (Figs. 4.22 and 4.23). The seventh cervical vertebra (vertebra prominens) has a long spinous process that is typically not bifid. This spinous process is easily palpable posteriorly at the base of the neck (Figs. 4.24–4.26). Also unique to the C3–C7 vertebrae are the uncinate processes. These hook-shaped projections are located bilaterally on the superior end plates of the vertebral bodies where the lateral edges curve upward. The uncinate processes help to prevent lateral movement of the cervical vertebrae (Figs. 4.15, 4.17, 4.20, and 4.22).

Superior articular process

Odontoid process (dens)

Transverse process

Inferior articular process

FIG. 4.16  Anterior view of C2 (axis).

Body

CHAPTER 4  Spine

181

S Occipital condyle

Odontoid process of C2 Atlantoaxial joint

Atlantooccipital joint Lateral mass of C1

Superior articular process of C2 R

L

Transverse process of C2

Body of C2

Uncinate process of C3 Body of C3 I

FIG. 4.17  Coronal CT reformat of C1 (atlas) and C2 (axis).

S

Occipital bone

Anterior arch of C1

Posterior arch of C1

Odontoid process of C2 A

P

Pharynx

Spinous process of C2

C2

Spinous process of C3

C3

Vertebral canal

I

FIG. 4.18  Sagittal CT reformat of C1 (atlas) and C2 (axis).

Superior articular process and anterior arch of C1

Odontoid process of C2 Body of C2

Superior articular process of C2

Posterior arch of C1

Atlantoaxial joint

Spinous process of C2

FIG. 4.19  Posterosuperior view of cervical vertebrae.

CHAPTER 4  Spine

182

S Occipital condyle

Odontoid process of C2

Atlantooccipital joint

Styloid process of temporal bone

Atlantoaxial joint

Lateral mass of C1 R

L

Transverse foramen of C1

Superior articular process of C2 Body of C2

Transverse process of C3

Uncinate process of C3 Body of C4

Body of C3 I

FIG. 4.20  3D CT of cervical vertebrae, anterior view.

Odontoid process (dens) Pars interarticularis

Superior articular process

Transverse foramen

Transverse process

Body Transverse process

Spinous process

Inferior articular process Uncinate process

Superior articular process

FIG. 4.21  Lateral view of C2 (axis).

Transverse foramen

Pedicle

Vertebral foramen

Lamina

Spinous process (bifid)

FIG. 4.22  Superior view of cervical vertebra with bi­ fid spinous process.

CHAPTER 4  Spine

Lamina

Spinous process (bifid)

A

Intervertebral foramen

P

Body

FIG. 4.23  Axial CT of cervical vertebra with bifid spinous process.

Body of C7

A

Transverse foramen

L

R

Spinous process C7

P

FIG. 4.24  Axial CT of C7 (vertebral prominens).

Transverse process C7

183

CHAPTER 4  Spine

184

S Posterior arch of C1 Posterior thecal sac

C2 C3

Spinal cord

C4 C5 C6

Spinous process of C7 (vertebral prominens)

C7 T1 T2

A

P T3 Spinous process of T4

T4 T5

Cerebrospinal fluid in subarachnoid space

T6 T7 T8 T9 T10

FIG. 4.25  Midsagittal, T2-weighted MRI of cervical

I

C2

Contrast in subarachnoid space

Spinal cord

and thoracic spine.

S

C1

Spinous process of C2

Spinous process of C3 Spinous process of C4 Spinous process of C5

C3 A

P

C4 C5

Spinous process of C6

C6 Spinous process of C7

C7

FIG. 4.26  Midsagittal CT reformat of cervical

I T1

spine, post-myelogram.

CHAPTER 4  Spine

185

Thoracic Vertebrae

Lumbar Vertebrae

Twelve vertebrae make up the thoracic section. They have typical vertebral configurations except for their four characteristic costal facets (demi-facets), two located on the body and two located on the transverse processes, that articulate with the ribs. The head of the rib articulates with the vertebral bodies at the costovertebral joints, whereas the tubercle of the ribs articulates with the transverse processes at the costotransverse joints. The spinous processes of the thoracic vertebrae are typically long and slender, projecting inferiorly over the vertebral arches of the vertebrae below (Figs. 4.7, 4.25, 4.27–4.29).

The lumbar section typically consists of five vertebrae. Their massive bodies increase in size from superior to inferior (Fig. 4.30). The largest of the lumbar vertebrae, L5, is characterized by its massive transverse processes. The entire weight of the upper body is transferred from the fifth lumbar vertebra to the base of the sacrum across the L5–S1 intervertebral disk (Figs. 4.9, 4.10, and 4.31– 4.35).

Body Costal facet of body

Costovertebral joint

A unilateral or bilateral stress fracture or defect of the pars interarticularis is termed spondylolysis. Spondy­ lolysis is most common at the L5 level and is a frequent cause of low back pain in adolescent athletes. Bilateral spondylolysis may result in spondylolisthesis, which is an anterior slippage of one vertebra over another. When the pars interarticularis of C2 is fractured, it is usually the result of hyperextension of the head and is commonly called a hangman’s fracture.

Rib Costotransverse Transverse process joint

Spinous process

Costal facet of transverse process

FIG. 4.27  Superior view of thoracic vertebra. A

Costovertebral joint

Body Costal facet of body Pedicle

R

L

Rib

Transverse process Lamina

Spinous process

P

Costal facet of transverse process

Costotransverse joint

FIG. 4.28  Axial CT of thoracic vertebra.

186

CHAPTER 4  Spine S

First rib

Spinal cord

Thoracic pedicle

R

L Medial end of rib

Costovertebral joint

Subarachnoid space with intrathecal contrast

Thecal sac Conus medullaris Lumbar pedicle

I

FIG. 4.29  Coronal CT reformat of thoracic spine with intrathecal contrast.

CHAPTER 4  Spine S T10

Rib

T11

Costovertebral joint

T12

L1

L2

L3

L4

R

L Transverse process

L5 Sacral promontory Sacrum

Sacral foramina

Coccyx

I

FIG. 4.30  3D CT of lumbar spine, anterior view.

187

188

CHAPTER 4  Spine S T10 Rib T11

Costovertebral joint

T12 Intervertebral foramen

L1

Transverse process

Pedicle L2

Inferior articular process

Intervertebral disk space

Zygapophyseal joint

L3 A

P Superior articular process

L4 Superior end plate

Spinous process

L5 body Inferior end plate L5–S1 disk space

Sacrum

Sacral promontory

A I S Superior articular process

Superior vertebral notch

Transverse process

Pedicle

Pars interarticularis

A

P

Body

Inferior vertebral notch

Spinous process Inferior articular process

B I

FIG. 4.31  (A) 3D CT of lumbar spine, lateral view. (B) 3D CT of lumbar vertebra, lateral view.

CHAPTER 4  Spine A Body

Pedicle

Vertebral foramen

R

L

Lamina Transverse process Superior articular process

Spinous process

C P

FIG. 4.31, cont’d (C) 3D CT of lumbar vertebra, superior view.

%RG\

6XSHULRU YHUWHEUDO QRWFK

3HGLFOH 6XSHULRUDUWLFXODU SURFHVV 7UDQVYHUVH SURFHVV 3DUV LQWHUDUWLFXODULV 6SLQRXV SURFHVV

,QIHULRU YHUWHEUDO QRWFK

,QIHULRU DUWLFXODU SURFHVV

FIG. 4.32  Lateral view of lumbar vertebra.

189

190

CHAPTER 4  Spine Body of L1

Pedicle

A

R

L

Lamina

Spinous process

P

Transverse process

FIG. 4.33  Axial CT of lumbar vertebra.

A

Body

Pedicle

R

L

Spinous process

P

FIG. 4.34  Axial CT of L5 vertebra (midbody).

Lamina

Transverse process

CHAPTER 4  Spine

191

S Epidural fat T12

Annulus fibrosus of intervertebral disk

Conus medullaris

L1

Spinous process of L1 L2

Nucleus pulposus of intervertebral disk

Supraspinous ligament A

L3

P

Anterior longitudinal ligament

Cauda equina L4

Posterior longitudinal ligament L5

S1

Thecal sac S2

I

FIG. 4.35  Midsagittal, T2-weighted MRI of lumbar spine.

Sacrum and Coccyx The sacral section consists of five vertebrae that fuse to form the sacrum. Their transverse processes combine to form the lateral masses (alae), which articulate with the pelvic bones at the sacroiliac joints. Located within the lateral masses are the sacral foramina that allow for the passage of spinal nerves (Figs. 4.30, 4.36, and 4.37). The lateral masses provide the lateral boundaries of the sacral canal, which is a continuation of the vertebral canal. The triangular-shaped sacral canal terminates at the sacral hiatus and communicates with the first four pairs of sacral foramina for the passage of the S1–S4 nerve roots (Fig. 4.39). The first sacral segment has a prominent ridge located on the anterior surface of the

body termed the sacral promontory (Figs. 4.38 and 4.39). This bony landmark is used to separate the abdominal cavity from the pelvic cavity. The spinous process of the fifth sacral segment is absent, leaving an opening termed the sacral hiatus (Fig. 4.2). Located at the sides of the sacral hiatus are the inferior articular processes of the fifth sacral segment, which project downward as the sacral cornu. Located inferior to the fifth sacral segment is the coccyx, which consists of three to five small fused bony segments (Figs. 4.36 and 4.38). Superior projections off the first coccygeal segment, called cornua, have ligamentous attachments to the sacral cornu that provide additional stability to the articulation between the sacrum and coccyx. The coccyx represents the most inferior portion of the vertebral column.

192

CHAPTER 4  Spine Ala or lateral mass

Body of first sacral segment

1

2

Sacral foramina

Sacrum 3 4 5 1 2 3

Coccyx

4

FIG. 4.36  Anterior view of sacrum and coccyx.

Sacral promontory

Ilium

S

Lateral mass

R

L

Sacral foramina

Body

I

Sacrum

FIG. 4.37  Coronal CT of sacrum and coccyx.

Sacroiliac joint

CHAPTER 4  Spine

193

S

S1 prSacral promontory S2

S3 A

P S4

Sacrum S5 1 Coccyx

2 3

I

FIG. 4.38  Sagittal, T1-weighted MRI of sacrum.

SI joint

Body

A

Sacral promontory

Sacral canal

Ilium

R

L

Lateral mass

P

FIG. 4.39  Axial CT of sacrum and sacroiliac joints.

Articular process

194

CHAPTER 4  Spine

LIGAMENTS There are several ligaments and membranes of the spine that serve to connect the cervical vertebrae and the cranium to provide mobility and protection for the head and neck. The apical ligament is a midline structure that connects the apex of the odontoid process to the inferior margin of the clivus (Figs. 4.40–4.42). The alar ligaments are two strong bands that extend obliquely from the sides of the odontoid process and upward to the lateral margins of the occipital condyles to limit rotation and flexion of the head (Figs. 4.43 and 4.44). The transverse ligament extends across the vertebral foramen of C1 to form a sling over the posterior surface of the odontoid process. It has a small band of longitudinal fibers that ascend to attach to the posteroinferior aspect of the clivus and inferiorly to attach to the body of the axis. The transverse ligament holds the odontoid process of C2 against the anterior arch of C1 (Figs. 4.43–4.46). The transverse ligament is sometimes called the cruciform ligament because of its crosslike appearance when viewed in the coronal plane. In addition to the ligaments listed previously, the stability of the suboccipital region of the spine is reinforced with the atlantooccipital and tectorial membranes. The atlantooccipital membrane consists of an anterior and posterior portion, which serve to connect the arches of the atlas with the occipital bone. The anterior atlantooccipital membrane passes from the anterior arch of the atlas and connects to the base of the occipital bone at its anterior margin (Fig. 4.40). This ligament is the superior

6SKHQRLGERQH 'XUDPDWHU &OLYXVRI RFFLSLWDOERQH $QWHULRUDWODQWRRFFLSLWDOPHPEUDQH

extension of the anterior longitudinal ligament. The posterior atlantooccipital membrane extends from the posterior arch of C1 to the occipital bone, closing the posterior portion of the vertebral canal between the cranium and C1 (Figs. 4.40–4.42). The tectorial membrane is a broad ligament that extends from the clivus of the occipital bone to the posterior body of the axis, covering the dens, transverse, apical, and alar ligaments. The tectorial membrane forms the anterior boundary of the vertebral canal and is continuous with the posterior longitudinal ligament (Figs. 4.40–4.42). Another important ligament of the cervical region is the ligamentum nuchae, which serves as an attachment point for muscles in the posterior portion of the neck. This expansive ligament extends from the external occipital protuberance of the cranium to the spinous processes of the cervical vertebrae (Figs. 4.40–4.42). The ligamentum nuchae continues inferiorly as the supraspinous ligament. The supraspinous ligament is a narrow band of fibers that runs over and connects the tips of the spinous processes from the seventh cervical vertebra to the lower lumbar vertebrae. The interspinous ligaments extend between adjacent spinous processes throughout the spinal column (Figs. 4.47–4.49). Several ligaments enclose the vertebral column to help protect the spinal cord and maintain the stability of the vertebral column. Two of the larger ligaments are the anterior and posterior longitudinal ligaments (Fig. 4.47). The anterior longitudinal ligament is a broad fibrous band that extends downward from C1 along the entire anterior surface of the vertebral bodies to the sacrum.

&19,,9,,,

&1,;;;, &1;,,

$SLFDOOLJDPHQW 7HFWRULDOPHPEUDQH $QWHULRUDUFKRIDWODV 2GRQWRLGSURFHVV RI& 7UDQVYHUVHOLJDPHQW $QWHULRUORQJLWXGLQDOOLJDPHQW ,QWHUYHUWHEUDOGLVN

6TXDPRXVSRUWLRQ RIRFFLSLWDOERQH 3RVWHULRU DWODQWRRFFLSLWDOPHPEUDQH 3RVWHULRUDUFKRI& ,QWHUVSLQRXVOLJDPHQW 6SLQRXVSURFHVV /LJDPHQWXPQXFKDH 'XUDPDWHURIWKHFDOVDF

3RVWHULRUORQJLWXGLQDOOLJDPHQW

FIG. 4.40  Midsagittal view of atlantooccipital joint.

CHAPTER 4  Spine Tectorial membrane

195

S

Clivus Posterior atlantooccipital membrane

Apical ligament Anterior atlantooccipital membrane

Ligamentum nuchae

Anterior arch of C1

Posterior longitudinal ligament

Odontoid process of C2 A

P

Anterior longitudinal ligament

Spinal cord

Supraspinous ligament

CSF in subarachnoid space

Interspinous ligament

I

FIG. 4.41  Midsagittal, T2-weighted MRI of cervical spine with spinal ligaments. Apical ligament

Transverse (cruciform) ligament

Tectorial membrane

Anterior atlantooccipital membrane

Posterior atlantooccipital membrane A

P

Ligamentum nuchae

Anterior longitudinal ligament

I

Posterior longitudinal ligament

FIG. 4.42  Sagittal CT reformat of atlantooccipital joint.

Interspinous ligament

CHAPTER 4  Spine

196

&OLYXVRI RFFLSLWDOERQH

/RQJLWXGLQDO EDQGRI WUDQVYHUVH OLJDPHQW 2FFLSLWDO FRQG\OH

$ODU OLJDPHQW

/DWHUDOPDVV RI& 6HFRQGFHUYLFDO YHUWHEUD

/RQJLWXGLQDO EDQGRI WUDQVYHUVH OLJDPHQW

7UDQVYHUVHEDQG RIWUDQVYHUVH OLJDPHQW

This ligament connects the anterior aspects of the vertebral bodies and intervertebral disks to maintain the stability of the joints and to help prevent hyperextension of the vertebral column. It is thicker in the thoracic region than in the cervical and lumbar regions, providing additional support to the thoracic spine. The posterior longitudinal ligament is narrower and slightly weaker than the anterior longitudinal ligament. It lies inside the vertebral canal and runs along the posterior aspect of the vertebral bodies (Figs. 4.47–4.53). Unlike the anterior longitudinal ligament, the posterior longitudinal ligament is attached only at the intervertebral disk and adjacent margins. It is separated from the middle of each vertebra by epidural fat, which provides passage of the basivertebral veins. The posterior longitudinal ligament runs the entire length of the vertebral column beginning at C2. This ligament helps prevent posterior protrusion of the nucleus pulposus and hyperflexion of the vertebral column. The ligamenta flava are strong ligaments (consisting of yellow elastic tissue) present on either side of the spinous processes. They join the laminae of adjacent vertebral arches, helping to preserve the normal curvature of the spine (Figs. 4.47–4.53).

FIG. 4.43  Posterior view of alar ligaments.

Clivus

S

Occipital condyle Alar ligament

Lateral mass of C1

Odontoid process R

L Transverse band of transverse ligament

Body of C2

I

FIG. 4.44  Coronal, T1-weighted MRI of alar ligaments.

CHAPTER 4  Spine A

Odontoid process of C2 Lateral mass of C1

L

R

Transverse band of transverse ligament Spinal cord

P

Posterior arch of C1

FIG. 4.45  Axial, T1-weighted MRI of cervical vertebra with transverse ligament.

$QWHULRU DUFKRI&

7UDQVYHUVH EDQGRIWUDQVYHUVH OLJDPHQW





3RVWHULRU DUFKRI&

2GRQWRLG SURFHVVRI&

FIG. 4.46  Axial CT of C1, C2, and transverse ligament.

197

198

CHAPTER 4  Spine Lamina

Transverse process Intertransverse ligament

Ligamentum flavum

Posterior longitudinal ligament

Transverse process Spinous process Interspinous ligament

Anterior longitudinal ligament

Supraspinous ligament Vertebral body

FIG. 4.47  Anterior oblique view of spinal ligaments.

Pedicle

S Lamina

Vertebral endplate

Ligamentum flavum

Nucleus Intervertebral pulposus disk Annulus fibrosus

Supraspinous ligament A

P

Anterior longitudinal ligament

Intervertebral foramen

Vertebral body Posterior longitudinal ligament

Interspinous ligament

I

FIG. 4.48  Sagittal view of spinal ligaments.

Spinous process

CHAPTER 4  Spine S

Supraspinous ligament

Anterior longitudinal ligament

A

P

Posterior longitudinal ligament

Interspinous ligament

Ligamentum flava

Thecal sac Filum terminale I

FIG. 4.49  Midsagittal, T2-weighted MRI of lumbar spine with spinal ligaments. Posterior longitudinal ligament

A

Anterior longitudinal ligament

L

R

Ligamentum flavum

P

Ligamentum nuchal

FIG. 4.50  Axial CT of cervical vertebra with spinal ligaments.

199

200

CHAPTER 4  Spine Descending aorta

A

Anterior longitudinal ligament

Vertebral body

Posterior longitudinal ligament R

L Thoracic spinal cord

Ligamentum flavum

Rib

Lamina

Epidural fat

P

FIG. 4.51  Axial, T2-weighted MRI of thoracic vertebra with spinal ligaments.

A Superior articular process

Zygapophyseal joint

R

L

Inferior articular process

Ligamentum flavum

Spinous process

P

Supraspinous ligament

FIG. 4.52  Axial CT of lumbar vertebra with spinal ligaments.

Posterior longitudinal ligament

CHAPTER 4  Spine

201

A Anterior longitudinal ligament

Posterior longitudinal ligament R

L Cauda equina

Ligamentum flava

Thecal sac

P

MUSCLES The muscles of the back can be separated into three groupings or layers: the superficial layer (splenius muscles), the intermediate layer (erector spinae group), and TABLE 4.1

FIG. 4.53  Axial, T1-weighted MRI of

Epidural fat

lumbar vertebra with spinal ligaments.

the deep layer (transversospinal group). The muscle groups that run the length of the spine can be divided into regions according to their location: capitis, cervicis, thoracis, and lumborum (Table 4.1).

Spinal Muscles

Muscle

Origin

Insertion

Splenius Splenius capitis

Nuchal ligament and spinous processes of C7–T4

Mastoid process of temporal bone and lateral aspect of occipital bone Transverse processes of C1–C3 or C4

Splenius cervicis Erector Spinae Iliocostalis Iliocostalis cervicis Iliocostalis thoracis Iliocostalis lumborum Longissimus Longissimus capitis Longissimus cervicis Longissimus thoracis Spinalis Spinalis capitis Spinalis cervicis Spinalis thoracis Transversospinal Semispinalis Semispinalis capitis Semispinalis cervicis Semispinalis thoracis Multifidus Rotatores

Spinous processes of T3–T6 Broad tendon arising from posterior iliac crest, sacrum, spinous processes of sacrum and inferior lumbar spine, and supraspinous ligament

Fibers run superiorly to cervical transverse processes of C4 to C7 and angles of lower ribs, 7-12

Broad tendon arising from posterior iliac crest, sacrum, spinous processes of sacrum and inferior lumbar spine, and supraspinous ligament

Fibers run superiorly to mastoid process of temporal bone and to transverse processes of thoracic and cervical vertebrae and just medial to the angles of the lower ribs

Broad tendon arising from posterior iliac crest, sacrum, spinous processes of sacrum and inferior lumbar spine, and supraspinous ligament

Fibers run superiorly to occipital bone and spinous processes of upper thoracic and cervical spine May blend with semispinalis capitis muscle

Transverse processes of cervical and thoracic spine

Fibers span 4–6 vertebral segments, running superomedially to occipital bone and spinous processes in cervical and thoracic spine

Sacrum, ilium, transverse processes of T1–L5 and articular processes of C4–C7

Fibers span 4–6 vertebral segments, running superomedially to spinous processes

Transverse processes of vertebrae, well developed in thoracic spine

Fibers run superomedially and attach to junction of lamina and transverse processes on same vertebra or spinous processes of vertebrae above their origin

202

CHAPTER 4  Spine nuchae. They are divided into a cranial portion, the splenius capitis, which inserts on the mastoid process of the temporal bone and on the lateral aspect of the occipital bone, and a cervical portion, the splenius cervicis, which inserts on the transverse processes of C1–C3 (Figs. 4.54–4.58). Together they act to extend the head and neck.

Superficial Layer The splenius muscles are located on the lateral and posterior aspect of the cervical and upper thoracic spine. These bandage-like muscles originate on the spinous processes of C7–T6 and the inferior half of the ligamentum

S

External occipital protuberance

Inferior nuchal line Mastoid process

Transverse process of C1 C2

Ligamentum nuchae

C3 C4 C5

Splenius capitis muscle

C6 C7

Spinous process of C7

T1

L

Splenius cervicis muscle

R

2 3

4 Spinous process of T4

5 6

Spinous process of T6

7 I

FIG. 4.54  Posterior view of splenius muscles.

A

Multifidus muscle

Spinalis cervicis muscle Splenius cervicis muscle

R

L Semispinalis capitis muscle Splenius capitis muscle P

Trapezius muscle

FIG. 4.55  Axial view of splenius muscles.

CHAPTER 4  Spine A

Multifidus muscle

R

L Semispinalis capitis muscle

Trapezius muscle

Levator scapulae muscle

Splenius capitis muscle

P

FIG. 4.56  Axial, T1-weighted MRI of cervical vertebra with spinal muscles.

A

Cervical vertebral body

Splenius cervicis muscle R

L Longissimus capitis muscle

Levator scapulae muscle

Semispinalis cervicis muscle

Lamina

Semispinalis capitis muscle

Multifidus muscle

Spinous process

Ligamentum nuchae

P

Trapezius Splenius muscle capitis muscle

FIG. 4.57  Axial CT of cervical vertebra with spinal muscles.

203

204

CHAPTER 4  Spine

Intermediate Layer The intermediate muscle group, the erector spinae muscle group, consists of massive muscles that form a prominent bulge on each side of the vertebral column. The erector spinae muscle group is the chief extensor of the vertebral column and is arranged in three vertical columns, the iliocostalis layer (lateral column), longissimus layer (intermediate column), and the spinalis layer (medial column) (Figs. 4.58 and 4.59). This muscle group arises from a common broad tendon from the posterior part of the iliac crest, sacrum, and inferior lumbar spinous

processes. The iliocostalis muscles run superiorly to attach to the angles of the lower ribs and transverse processes of C7–C4. The longissimus muscles run superiorly to insert into the tips of the transverse processes of the thoracic and cervical regions, medial to the angles of the lower ribs, and the mastoid process. The narrow spinalis muscle group extends from the spinous processes of the upper lumbar and lower thoracic regions to the spinous processes of the superior thoracic spine, cervical spine, and occipital bone (Figs. 4.58–4.63). The spinalis muscles are most prominent in the thoracic region and may be absent or blend with the semispinalis muscles in the cervical region. Occipital bone

Ligamentum nuchae Splenius capitis

Superior nuchal line Semispinalis capitis

Longissimus capitis

Vertebra prominens (spinous process of C7)

Iliocostalis cervicis

Splenius cervicis

Iliocostalis Erector spinae group

Longissimus

Spinalis

Iliocostalis lumborum

Transversus abdominis Iliac crest Common broad tendon of erector spinae muscle group

Posterior superior iliac spine

Sacrum

FIG. 4.58  Posterior view of erector spinae muscle group.

CHAPTER 4  Spine

Deep Layer

A Rotatores muscle

T9

Multifidus muscle Semispinalis muscle

R

L Vertebral groove

Longissimus muscle

Iliocostalis muscle

P

205

Spinalis muscles

FIG. 4.59  Axial view of erector spinae muscle group at the thoracic level.

The transversospinal muscles consist of several short muscles that are located in the groove between the transverse and spinous processes of the vertebrae. They can be separated into the semispinalis, multifidus, and rotatores and have a primary function to flex and rotate the vertebral column (Figs. 4.59–4.64). The semispinalis muscles arise from the thoracic and cervical transverse processes and insert on the occipital bone and spinous processes in the thoracic and cervical regions. The semispinalis muscles form the largest muscle mass in the posterior portion of the neck. The multifidus muscles consist of many fibrous bundles that extend the full length of the spine and are the most

A

Thoracic vertebra Rotatores muscle R

L

Multifidus muscle

Spinalis muscle

Semispinalis muscle

Longissimus muscle

Iliocostalis muscle

Trapezius muscle P

FIG. 4.60  Axial, T2-weighted MRI of thoracic vertebra with spinal muscles.

A

Thoracic vertebra

Semispinalis muscle

R

L

Rotatores muscle

Iliocostalis muscle

Multifidus muscle

Longissimus muscle

Trapezius muscle

P

Spinalis muscle

FIG. 4.61  Axial CT of thoracic vertebra with spinal muscles.

CHAPTER 4  Spine

206

S

Semispinalis thoracis muscle

R

L Ribs

Spinous process Iliocostalis thoracis muscle

Multifidus muscle I

Longissimus thoracis muscle

FIG. 4.62  Coronal, T1-weighted MRI of thoracic vertebrae with spinal muscles. S

Rib

Iliocostalis thoracis muscle Spinalis thoracis muscle R

L Longissimus thoracis muscle

Semispinalis thoracis muscle

Multifidus muscle

Spinous process Iliac crest I

FIG. 4.63  Coronal CT reformat of lumbar vertebrae with spinal muscles.

CHAPTER 4  Spine prominent in the lumbar region. The deepest of the transversospinal muscles are the rotatores, which connect the lamina of one vertebra to the transverse process of the vertebra below. They are best developed in the thoracic region.

Two additional muscles that are commonly visualized in the lumbar region of the spine are the quadratus lumborum and the psoas muscles, which are considered abdominal muscles (Figs. 4.65–4.68). Further information on these muscles can be found in Chapter 7.

Rectus capitis posterior minor Superior oblique capitis Spinous process Semispinalis capitis

Rectus capitis posterior major Transverse process Inferior oblique capitis

Vertebra prominens (spinous process of C7)

207

Rotatores (long, short)

Semispinalis thoracis

Levatores costarum (short, long)

Intertransverse Quadratus lumborum Multifidus Iliac crest

Erector spinae (cut)

FIG. 4.64  Posterior view of transversospinal muscle group.

208

CHAPTER 4  Spine S

Left crus of diaphragm Quadratus lumborum

Right crus of diaphragm

Psoas minor Psoas major R

L

Piriformis

Anterior superior iliac spine

Coccygeus

Illiacus

Inguinal ligament

Pectineus

Levator ani Pubic tubercle

Tensor fasciae latae

A

P Quadratus lumborum muscle

Psoas muscle

Transversospinal muscle Erector spinae muscle

Deep layer of thoracolumbar fascia

B

Posterior layer of thoracolumbar fascia

Latissimus dorsi muscle

Middle layer of thoracolumbar fascia

Transversus abdominis muscle Internal oblique muscle External oblique muscle

FIG. 4.65  (A) Anterior view of quadratus lumborum and psoas muscles. (B) Axial view of quadratus lumborum and psoas muscles. S

Spinous process Quadratus lumborum muscle Iliocostalis lumborum L muscle

R Sacroiliac joint

I

FIG. 4.66  Coronal, T1-weighted MRI of quadratus lumborum muscle.

CHAPTER 4  Spine

209

Quadratus lumborum muscle

A

Psoas muscle L

R

Iliocostalis muscle

P

Longissimus muscle

Transversospinal (multifidus) muscle

FIG. 4.67  Axial, T2-weighted MRI of lumbar vertebra with spinal muscles.

A

Psoas muscle

L

R

Quadratus lumborum muscle

Iliocostalis muscle

P

Longissimus Transversospinal muscle (multifidus) muscle

FIG. 4.68  Axial CT of lumbar vertebra with spinal muscles.

CHAPTER 4  Spine

210

SPINAL CORD Spinal Meninges Throughout its length, the delicate spinal cord is surrounded and protected by cerebrospinal fluid, which is contained in the thecal sac formed by the spinal meninges (Fig. 4.69). The spinal meninges are continuous with the cranial meninges and can be broken into the same three

Cervical vertebrae

Cranial meninges

1 2 3 4 5 6 7

1 2 3 4 5 7 8 1

1

2

2

3

3

4

4

6

6

7

7

Thoracic nerves

Epidural space

L1 Conus medullaris

8

8

9

9

10

10

11

11

Lumbar vertebrae

T12

5

5

Conus medullaris

Cervical nerves

6

Brachial plexus

Thoracic vertebrae

layers: dura, arachnoid, and pia. The dura mater is the tough outer layer that extends to approximately the level of S2, creating the thecal sac (Figs. 4.29, 4.49, and 4.69– 4.72). The anterior thecal sac adheres to the posterior longitudinal ligament and is separated from the vertebral column by an epidural space that contains fat and vessels. Each spinal nerve is surrounded by dura mater that extends through the intervertebral foramen called the dural nerve root sleeve. The arachnoid mater is the thin

12

12 1

1

2

2

3

3

4

4

5

5

Cauda equina

Dura mater Subarachnoid space

Lumbar nerves

L2 Thecal sac Subarachnoid space

L3

Filum terminale

L4

Thecal sac

L5 S1

1 2 3

S2 Sacral nerves

S3

4

S4

5

S5 C1 Coccygeal nerve

Filum terminale

FIG. 4.69  Posterior view of spinal meninges, thecal sac, and spinal cord.

2 3 5

4

FIG. 4.70  Midsagittal view of thecal sac, conus medullaris, and filum terminale.

CHAPTER 4  Spine

211

S

Thecal sac

CSF in subarachnoid space

Conus medullaris

A

P

Cauda equina

Filum terminale

I

FIG. 4.71  Midsagittal, T2-weighted MRI of thecal sac, conus medullaris, and filum terminale.

CHAPTER 4  Spine

212

S Conus medullaris

Cauda equina

A

P Thecal sac Subarachnoid space with intrathecal contrast

L5

Thecal sac termination

Sacrum

I

Filum terminale

FIG. 4.72  Sagittal CT reformat of lumbar spine with thecal sac, post-myelogram. transparent membrane that is attached to the inner surface of the dura mater. A potential space called the subdural space runs between the arachnoid and dura mater. The arachnoid mater is connected to the pia mater by numerous delicate strands, creating the spiderlike appearance associated with the arachnoid mater. The space between the arachnoid mater and pia mater is the subarachnoid space, which is filled with cerebrospinal fluid and the blood vessels that supply the spinal cord (Figs. 4.69–4.74). The pia mater is a highly vascular layer that closely adheres to the spinal cord. At the distal end of the spinal cord, approximately L1, the pia mater continues as a long, slender strand called the filum terminale. The filum terminale descends through the subarachnoid space to the inferior border of the thecal sac, where it is reinforced by the dura mater. After leaving the thecal sac, it eventually exits the sacral canal through the sacral hiatus and attaches to the coccyx, providing an anchor between the spinal cord and the coccyx (Figs. 4.49, 4.69, and 4.70). In addition, lateral extensions of the pia mater leave the spinal cord to form pairs of denticulate ligaments,

which attach to the dura, preventing lateral movement of the spinal cord within the thecal sac. The denticulate ligaments run between the ventral and dorsal nerve roots within the spinal column (Fig. 4.75). After producing chickenpox, the herpes zoster virus can lie dormant within the ventral horns of the spinal cord for years. When reactivated, the virus attacks the dorsal roots of peripheral nerves, producing a painful rash with a distribution that corresponds to the affected sensory nerve. This condition is termed shingles.

Spinal Cord and Nerve Roots The spinal cord functions as a large nerve cable that connects the brain with the body. It begins as a continuation of the medulla oblongata at the inferior margin of the brainstem and extends to approximately the first lumbar vertebra. The spinal cord tapers into a cone-shaped segment called the conus medullaris (Figs. 4.69–4.72 and

CHAPTER 4  Spine

Spinal nerve

Dorsal horn

Ventral horn

Anterior median fissure

Body of vertebra Central canal Gray matter

Ventral root

Ventral ramus

Dural nerve root sleeve

Dorsal root ganglion Dorsal root

Dorsal ramus

White matter Subdural space Epidural space (contains fat) Subarachnoid space

Dura mater Arachnoid Posterolateral sulcus

Posterior median sulcus

Spinal meninges

Pia mater

FIG. 4.73  Axial view of spinal meninges, dural spaces, and spinal cord.

Ventral root

Cervical spinal cord

Vertebral body

A

R

L

Dorsal root Epidural fat

Spinous process

P

Subarachnoid space with intrathecal contrast

FIG. 4.74  Axial CT of cervical spine, post-myelogram.

Lamina

213

214

CHAPTER 4  Spine

Denticulate ligament

A

Cervical spinal cord

Thecal sac

Subarachnoid space Lamina L

R

P

FIG. 4.75  Axial, T2-weighted MRI of cervical spine with denticulate ligament.

4.76–4.79). The conus medullaris is the most inferior portion of the spinal cord and is located at approximately the level of T12–L1. At the termination of the spinal cord, nerves continue inferiorly in bundles. This grouping of nerves has the appearance of a horse’s tail and is termed the cauda equina, which exits through the lumbosacral foramina (Figs. 4.69, 4.76, 4.77, 4.80, and 4.81). The spinal cord retains the anterior and posterior fissures of the medulla oblongata, which extend along the length of the spinal cord. The anterior median fissure extends into the spinal cord at an average depth of 3 mm. The posterior median sulcus is shallower but together with the anterior median fissure separates the spinal cord into symmetric right and left halves. There is a shallow depression on each side of the posterior median sulcus called the posterolateral sulcus. These depressions mark the location where the ventral nerve rootlets enter the spinal cord (Figs. 4.73 and 4.91). The spinal cord is composed of white and gray matter. The white matter (myelinated axons) comprises the external borders of the cord and is more abundant. The gray matter is composed of nerve cells and runs the entire length of the cord. It is centrally located and surrounds the central canal, which contains cerebrospinal fluid and

is continuous with the ventricles of the brain (Figs. 4.73, 4.82, and 4.91). In cross-section, the gray matter has the appearance of a butterfly. The two posterior projections are the dorsal horns, and the two anterior projections are the ventral horns (Fig. 4.73). The dorsal horns contain neurons and sensory fibers that enter the cord from the body periphery via the dorsal roots at the posterolateral sulcus. These are called the afferent (sensory) nerve roots (Figs. 4.74, 4.78, 4.79, 4.88, and 4.91). The dorsal root ganglion, an oval enlargement of the dorsal root that contains the nerve cell bodies of the sensory neurons, is located in the intervertebral foramen (Figs. 4.73 and 4.84–4.91). The ventral horns contain the nerve cell bodies of the efferent (motor) neurons. The efferent (motor) nerve roots exit the spinal cord via the ventral root to be distributed throughout the body (Figs. 4.78, 4.79, 4.83, 4.84, and 4.88). Just outside the intervertebral foramina, the ventral and dorsal roots unite to form the 31 pairs of spinal nerves. Of these nerve pairs, 8 correspond to the cervical region, 12 belong to the thoracic section, 5 correspond to the lumbar region, 5 correspond to the sacrum, and 1 belongs to the coccyx (Figs. 4.76, 4.88, and 4.91–4.93). Each spinal nerve provides a specific cutaneous distribution that can be demonstrated on a dermatome map (Fig. 4.94). (Text continues on page 229)

CHAPTER 4  Spine S

Conus medullaris

T12

Pedicle L1

Radicular vessels Cauda equina

L2

L3

L Psoas muscle

R

L4 I Dorsal root ganglion

Sacral promontory

L5

I

FIG. 4.76  Coronal, T2-weighted MRI of spinal cord, conus medullaris, and cauda equina. S Conus medullaris

Cauda equina

R

L

Dorsal root ganglion L4 pedicle

Body of L5

I

Spinal nerve root in intervertebral foramen

Sacral promontory

FIG. 4.77  Coronal CT reformat of spinal cord, conus medullaris, and cauda equina, post-myelogram.

215

216

CHAPTER 4  Spine IVC

A

Aorta

Ventral root

R

L

Conus medullaris Dorsal root

P

FIG. 4.78  Axial, T1-weighted MRI of conus medullaris.

A

Ventral root

Conus medullaris R

L

Rib Epidural fat

Dorsal root

P

Subarachnoid space with intrathecal contrast

FIG. 4.79  Axial CT of conus medullaris.

CHAPTER 4  Spine Thecal sac

A

R

L

Epidural fat

Cauda equina

P

Multifidus muscle

FIG. 4.80  Axial, T2-weighted MRI of cauda equina.

Thecal sac

A Basivertebral vein Contrast in intrathecal sac

L

R

Cauda equina

P

FIG. 4.81  Axial CT of cauda equina.

217

CHAPTER 4  Spine

218

S Lateral ventricle

Third ventricle

Pons R

L Trigeminal nerve (CN V) Medulla oblongata Spinal cord Central canal of spinal cord

I

FIG. 4.82  Coronal, T2-weighted MRI of brain and spinal cord with central canal.

A Ventral root

R

L

Conus medullaris Dorsal root

P

FIG. 4.83  Axial, T1-weighted MRI of spinal cord with ventral and dorsal roots.

CHAPTER 4  Spine Ventral root Dorsal root ganglion Intervertebral disk Spinous process

Vertebral body

Intervertebral foramen

Pedicle

FIG. 4.84  Sagittal view of spine with intervertebral foramina.

S Superior articular process

Intervertebral foramina

Dorsal root ganglion P

A

Pedicle Body of lumbar vertebra

I

FIG. 4.85  Sagittal, T1-weighted MRI of lumbar spine with intervertebral foramina.

219

220

CHAPTER 4  Spine Lumbar vertebral body

A

R

L

Cauda equina

P

Dorsal root ganglion

FIG. 4.86  Axial, T1-weighted MRI of lumbar vertebra with dorsal root ganglion.

A

R

Lumbar vertebral body

L

Dorsal root ganglion Lamina

Nerve roots of cauda equina

Spinous process

P

FIG. 4.87  Axial CT of lumbar vertebra with dorsal root ganglion, post-myelogram.

Psoas muscle

CHAPTER 4  Spine

Arachnoid matter Dura matter

Vertebral body

Subarachnoid space

Pedicle

Pia matter Dorsal root Dural nerve root sleeve

Ventral root

Dorsal root ganglion

Spinal nerve

Spinal cord

Ventral ramus

Dorsal ramus Intervertebral disk

FIG. 4.88  Coronal view of spinal dural nerve root sleeve.

221

CHAPTER 4  Spine

222 Thecal sac

Dorsal root

S

Lumbar spine

S

Psoas muscle

Psoas muscle

R L

R

L Nerve roots of cauda equina

Dorsal root ganglion

Transverse process of L5

Sacrum

I Ventral Dorsal ramus ramus

I

Dorsal root ganglion

FIG. 4.90  Coronal CT reformat with nerve roots of cauda equina, post-myelogram. FIG. 4.89  Coronal, T2-weighted MRI of dural nerve root sleeve and dorsal root ganglion.

CHAPTER 4  Spine

C1 C2 C3 Cervical nerves

C4 C5 C6 C7 C8 T1 T2 T3 T4 T5

Subdural space

Posterior

Cervical cord

Anterior median fissure Gray matter

Dura mater Arachnoid mater Dorsal rootlets

White matter

Central canal Dorsal horn

Anterior

Posterolateral sulcus Posterior median sulcus Thoracic cord Ventral horn

T6 Thoracic nerves

T7

Dorsal root ganglion

Dorsal horn

T8 T9

Subarachnoid space

Lumbar cord

Ventral horn

T10 T11

Dorsal horn

T12 L1

Conus medullaris

Sacral cord Ventral horn Dorsal horn

L2 Lumbar nerves

Cauda equina

B

L3 L4

Thecal sac

L5 Sacral and coccygeal nerves

S1-S5, coccygeal nerve

A

FIG. 4.91  (A) Posterior view of spinal cord and meninges. (B) Transverse sections through spinal cord.

223

CHAPTER 4  Spine

224

A

Sacrum

Sacroiliac joint Sacral nerve R

L

Thecal sac

P

FIG. 4.92  Axial, T1-weighted MRI of sacral nerves.

C3

C2

C5

C3

C4

C5 T2

C6 T2

C7 A

C4

T2

T4

T4

T6

T6

T8

T8

T10

C6 C7 C8

T2

T10 T12

C8 T1

L1

T12

L2

L1

S4 S3

T1

L2

L2 R

L3 S2

L3 L L5

Sacrum

P

Sacral nerve

FIG. 4.93  Axial CT of sacrum with nerves.

L4

L4

L5

S1 S1 L5

FIG. 4.94  Dermatomes. Left (anterior) and right (posterior) distri­ bution of dermatomes on the surface of the skin.

CHAPTER 4  Spine S

Odontoid process of C2 Lateral mass of C1

R

L

Transverse band of transverse ligament

P

Cervical spinal cord

CSF in subarachnoid space

FIG. 4.95  Axial, T1-weighted MRI of cervical spinal cord.

Cervical spinal cord

A

Subarachnoid space with intrathecal contrast

R

L

P

FIG. 4.96  Axial CT of cervical spinal cord, post-myelogram.

225

226

CHAPTER 4  Spine Descending aorta

A

Anterior longitudinal ligament

Vertebral body

Posterior longitudinal ligament R

L Thoracic spinal cord

Ligamentum flavum

Rib

Lamina

Epidural fat

P

FIG. 4.97  Axial, T1-weighted MRI of thoracic spinal cord.

Vertebral body

Thoracic spinal cord A

Descending aorta

L

R

Rib

Spinous process

P

FIG. 4.98  Axial CT of thoracic spinal cord, post-myelogram.

Intrathecal contrast in subarachnoid space

CHAPTER 4  Spine

227

A Ventral root

R

L

Conus medullaris

Dorsal root

P

FIG. 4.99  Axial, T1-weighted MRI of conus medullaris at T12.

A

R

L

Epidural fat Intrathecal contrast in subarachnoid space Ventral root

Dorsal root

P

Conus medullaris

FIG. 4.100  Axial CT of conus medullaris at T12, post-myelogram.

228

CHAPTER 4  Spine

Ventral roots

Spinal nerve

Ventral ramus

Dorsal ramus

Dorsal roots

FIG. 4.101  Distribution of ventral and dorsal rami in transverse section of spinal cord.

C1 Cervical plexus (C1–C4, upper C5)

C4

T1

Brachial plexus (C5–C8, T1)

Intercostal nerves

T12 L1

Lumbar plexus (T12, L1–L4)

L5

S1

Lumbosacral plexus (L4–L5 and S1–S4) S5 Sacral plexus

FIG. 4.102  Anterior view of major nerve plexuses.

CHAPTER 4  Spine

PLEXUSES The spinal cord is enlarged in two regions by the cell bodies of nerves that extend to the extremities. The cervical enlargement extends from the vertebral bodies of approximately C3–C7, and the lumbosacral enlargement occurs within the lower thoracic region. Cross-sectional images of the spinal cord at various levels show considerable differences in size and shape because of the changing proportion of gray and white matter (Figs. 4.91 and 4.95–4.100). Shortly after emerging from the intervertebral foramen, each nerve divides into dorsal and ventral rami, which contain both motor and sensory fibers (Fig. 4.101). The dorsal rami of all spinal nerves extend posteriorly to innervate the skin and muscles of the posterior trunk. The ventral rami of T2–T12 pass anteriorly as the intercostal nerves to supply the skin and muscles of the anterior and lateral trunk. The ventral rami of all other spinal nerves form complex networks of nerves called plexuses. These plexuses serve the motor and sensory needs of the muscles and skin of the extremities. The four major nerve plexuses are the cervical, brachial, lumbar, and sacral (Fig. 4.102).

Cervical Plexus The cervical plexus arises from the upper four ventral rami of C1–C4 to innervate the neck, the lower part of the face and ear, the side of the scalp, and the upper thoracic area. The major motor branch of this plexus is the phrenic nerve, which is formed by the branches of C3, C4, and the upper division of C5. This nerve descends vertically down the neck and passes into the superior thoracic aperture, where it continues inferiorly to the diaphragm (Figs. 4.102–4.106). The phrenic nerve, which innervates the diaphragm, is formed by motor fibers from C3–C5. A primary danger of a broken neck is that an injury at or above the level of C4 may result in paralysis of respiratory muscles, resulting in breathing difficulties and impaired speech production.

Brachial Plexus The brachial plexus is a large, complex network of nerves arising from the five ventral rami of C5–C8 and T1. The brachial plexus is located posterior to the subclavian artery as it courses toward the axillary region of the shoulder (Figs. 4.107–4.109). The roots of the

229

brachial plexus emerge between the anterior and middle scalene muscles to form three trunks: superior, middle, and inferior. The trunks continue laterally and inferiorly to form three cords just posterior to the clavicle. The cords extend through the axilla to form five terminal branches: the musculocutaneous, axillary, median, radial, and ulnar nerves. These nerves provide innervation for the muscles of the upper extremity and shoulder, with the exception of the trapezius and levator scapula muscles (Figs. 4.107–4.115).

Lumbar Plexus The lumbar plexus consists of six nerves arising from the ventral rami of T12 and L1–L4. The lumbar plexus is situated on the posterior abdominal wall, between the psoas major muscle and the transverse processes of the lumbar vertebrae. In general, it serves the lower abdominopelvic region and anterior and medial muscles of the thigh. The femoral nerve is the largest branch of the lumbar plexus descending beneath the inguinal ligament (Fig. 4.117). At the level of the lesser trochanter, the femoral nerve divides into several branches, the largest being the saphenous nerve, which descends along the medial aspect of the leg to the ankle, accompanied by the great saphenous vein. The saphenous nerve innervates the anterior lower leg, some of the ankle, and part of the foot (Figs. 4.116–4.119).

Paraplegia will result from transection of the spinal cord between the cervical and lumbosacral enlarge­ ments. Quadriplegia will result if the transection occurs above the level of C3.

Sacral Plexus Arising from L4–L5 and S1–S4, the nerves of the sacral plexus innervate the buttocks, posterior thigh, and feet. These nerves converge toward the inferior sacral foramina to unite into a large, flattened band. Most of this nerve network continues into the thigh as the sciatic nerve, which is the largest nerve in the body. The sciatic nerve exits the pelvis through the greater sciatic foramen and continues to descend vertically along the posterior thigh. In its course, it divides into the tibial and peroneal nerves, which innervate the posterior aspect of the lower extremity. The sacral plexus lies against the posterolateral wall of the pelvis between the piriformis muscle and internal iliac vessels, just anterior to the sacroiliac joint (Figs. 4.116, 4.117, and 4.120–4.124). (Text continues on page 241)

230

CHAPTER 4  Spine S

Spinal cord

Cervical plexus R

L

Cervical transverse processes

Sternocleidomastoid muscle

Middle scalene muscle Subclavian artery

Brachial plexus I

FIG. 4.103  Coronal, T1-weighted MRI of cervical plexus. S Mastoid air cells Occipital condyle Transverse process of C1

Cervical spinal cord

Cervical plexus R

L

Zygapophyseal joint Cervical transverse processes

Nerve rootlets (ventral)

First rib

I

FIG. 4.104  Coronal CT reformat of cervical plexus.

CHAPTER 4  Spine Spinal nerve in intervertebral foramen

Nerve rootlets of cervical plexus S

Spinal cord

A

Spinous process

P

I

FIG. 4.105  Sagittal oblique, T2-weighted MRI of cervical plexus. Right vagus nerve

Trachea

Left vagus nerve Left common carotid artery Left subclavian artery

Right phrenic nerve

Left phrenic nerve

Azygos vein Aorta Right pulmonary arteries

231

Ligamentum arteriosum Left pulmonary artery

SVC Pulmonary veins

Right atrium Right ventricle

Diaphragm Left ventricle

FIG. 4.106  Coronal view of phrenic nerve in thoracic cavity.

232

CHAPTER 4  Spine

Clavicle Axillary nerve

Humerus Radial nerve Musculocutaneous nerve

Radial nerve (superficial branch)

Median nerve Ulnar nerve

Radius

Ulna

Dorsal branch of ulnar nerve

Muscular branch

Superficial branch of ulnar nerve

Median nerve

Digital branch of ulnar nerve

Digital branch

Dorsal scapular Nerve to subclavius

Roots: C4 C5 C6

Suprascapular

C7

Posterior divisions

C8

Lateral Cords Posterior

Superior Middle Inferior

T1

Median

Long thoracic

Axillary

Medial pectoral

Musculocutaneous

Lateral pectoral Upper subscapular

Radial

Lower subscapular

Median

Thoracodorsal Ulnar

Medial cutaneous nerves of the arm and forearm

FIG. 4.107  Anterior view of brachial plexus.

Trunks

CHAPTER 4  Spine

233

Anterior scalene muscle Middle scalene muscle Posterior scalene muscle Superior trunk Middle trunk Clavicle

Inferior trunk

Sternum Scapula Common carotid artery Subclavian vein Subclavian artery

FIG. 4.108  Anterior oblique view of brachial plexus.

Right vertebral artery

Parotid gland

S

Odontoid process of C2

Sternocleidomastoid muscle

R

L

Right subclavian vein

Brachial plexus

I

FIG. 4.109  Coronal, T1-weighted MRI of brachial plexus.

Left Subclavian artery

234

CHAPTER 4  Spine Trachea Esophagus Thyroid gland

Sternocleidomastoid muscle

Anterior scalene muscle

Left internal jugular vein Left common carotid artery

Brachial plexus Middle scalene muscle

Multifidus muscle

Posterior scalene muscle

Trapezius muscle

Spinal cord

Semispinalis capitis muscle Splenius capitis muscle

FIG. 4.110  Axial view of brachial plexus.

Esophagus

A

Trachea

Thyroid gland

Internal jugular vein

Anterior scalene muscle

Common carotid artery

Brachial plexus R

L Middle scalene muscle

Vertebral body

Spinal cord

Thecal sac

P

FIG. 4.111  Axial, T1-weighted MRI of brachial plexus.

CHAPTER 4  Spine Sternocleidomastoid muscle

Thyroid gland

A

Trachea

235

Esophagus Anterior scalene muscle

Internal jugular vein

Brachial plexus

Common carotid artery

Middle scalene muscle R

L

P

FIG. 4.112  Axial CT of brachial plexus.

S

Odontoid process of C2 Parotid gland

R Sternocleidomastoid muscle

C2

L

C3 C4

Middle scalene muscle

C5 C6 C7

Brachial plexus

T1

I

FIG. 4.113  Coronal, T1-weighted MRI of cervical spine and brachial plexus.

236

CHAPTER 4  Spine Sternocleidomastoid muscle

S

Clavicle

Internal jugular vein

Middle scalene muscle Anterior scalene muscle A

P

Subclavian vein

Subclavian artery

Brachial plexus

I

Lung

FIG. 4.114  Sagittal, T1-weighted MRI of brachial plexus and scalene muscles.

Pectoralis major

Clavicle

Serratus anterior muscle

S

Trapezius muscle

Supraspinatus muscle

P

A

Subclavian vein

Subclavian artery

I

Brachial plexus

FIG. 4.115  Sagittal, T1-weighted MRI of brachial plexus.

CHAPTER 4  Spine

237

L1 Psoas muscle Iliohypogastric nerve

L2

Ilioinguinal nerve Genitofemoral nerve

L3

Lateral femoral cutaneous nerve

L4

Obturator nerve Iliacus muscle

L5

Femoral nerve S1 S2 S3 S4

Superior gluteal nerve Inferior gluteal nerve Piriformis muscle Posterior femoral cutaneous nerve Pudendal nerve Sciatic n Common peroneal part Tibial part

FIG. 4.116  Anterior view of lumbar and sacral plexuses. Sacrum Gluteal nerves

T12 L1

Lumbar plexus

L2

Sciatic nerve

L3

Femoral nerve

L4 L5

Sacral plexus

Posterior femoral cutaneous nerve

Inguinal ligament

FIG. 4.117  Anterior and posterior views of lumbar and sacral plexuses. Tibial nerve Peroneal nerve

Saphenous nerve

Anterior

Posterior

CHAPTER 4  Spine

238

S

Psoas muscle

Pedicle

Lumbar nerve

Segmental artery R

L

Thecal sac Sacral nerve Sacroiliac joint

I

FIG. 4.118  Coronal, T1-weighted MRI of lumbar plexus. S Superior articular process Pedicle

Dorsal root ganglion A

P Spinal artery

Lumbar vertebra

Sacrum

I

FIG. 4.119  Sagittal, T1-weighted MRI of lumbar vertebra.

CHAPTER 4  Spine Ilium

239

Sacroiliac joints

S

Gluteus medius muscle Gluteus maximus muscle

Sacrum Ilium

Piriformis muscle R

L Levator ani muscle

Sacral plexus

Ischium Semitendinosus and biceps femoris (common tendon attachment)

Obturator internus muscle

Adductor magnus muscle attachment I

FIG. 4.120  Coronal, T1-weighted MRI of sacroiliac joints and sacral plexus.

A Sacrum

Sacroiliac joint

Sacral nerve

R

L

Thecal sac

P

FIG. 4.121  Axial, T1-weighted MRI of sacrum and sacral nerve.

240

CHAPTER 4  Spine A Femoral nerve Femoral artery Femoral vein

Femoral head

Greater trochanter R

L Acetabulum

IT band

Sciatic nerve

Gluteus maximus muscle

P

FIG. 4.122  Axial, T1-weighted MRI of femoral head and sciatic nerve, right hip.

Femoral vein

Femoral artery

A

Fovea capitis

Femoral head

Acetabulum

Bladder R L Obturator internus muscle

Piriformis muscle

Sciatic nerve

Gemellus muscle

P

Gluteus maximus muscle

FIG. 4.123  Axial CT of femoral head and sciatic nerve, left hip.

Greater trochanter

CHAPTER 4  Spine S

Femur

A

Rectus femoris muscle

241

P

Vastus intermedius muscle

Lesser trochanter

I

Quadratus femoris muscle

Sciatic nerve

FIG. 4.124  Sagittal, T1-weighted MRI of sciatic nerve.

VASCULATURE Spinal Arteries The spinal cord is supplied by the anterior spinal artery, paired posterior spinal arteries, and a series of spinal branches. The anterior spinal artery is formed, just caudal to the basilar artery, by the union of two small branches of the vertebral arteries (Fig. 4.125). It runs the entire length of the spinal cord in the anterior median fissure and supplies the anterior two-thirds of the spinal cord (Figs. 4.125–4.127). The posterior spinal arteries arise as small branches of either the vertebral or the posterior inferior cerebellar arteries. They descend along the dorsal surface of the spinal cord and supply the posterior one-third of the spinal cord (Fig. 4.128). There exist frequent anastomoses joining the two posterior spinal arteries with each other and with the anterior spinal artery. Arising from the posterior aspect of the descending aorta are segmental arteries that supply the vertebral column and spinal cord. They are termed the intercostal arteries in the thoracic region and lumbar arteries in the

lumbar region. These vessels extend toward the intervertebral foramen, where they divide into spinal branches (Figs. 4.128–4.131). After giving off an anterior and posterior branch to the walls of the vertebral column, the spinal branches divide into anterior and posterior radicular arteries that pass along the ventral and dorsal roots into the spinal cord (Fig. 4.128). The anterior radicular arteries contribute blood to the anterior spinal artery, and the posterior radicular arteries contribute blood to the posterior spinal arteries. The largest of the radicular arteries is the great anterior radicular artery (artery of Adamkiewicz), which arises in the lower thoracic and upper lumbar region, typically between T12 and L3 (Figs. 4.125 and 4.127). This vessel makes a major contribution to the anterior spinal artery and provides the main blood supply to the inferior two-thirds of the spinal cord. An injury of the great radicular artery (artery of Adam­ kiewicz) may result in paralysis of the lower limbs be­ cause the artery provides the main blood supply to the inferior two-thirds of the spinal cord.

CHAPTER 4  Spine Anterior view Posterior cerebral artery Superior cerebellar artery Basilar artery Anterior inferior cerebellar artery

Anterior median fissure

Posterior inferior cerebellar artery Anterior spinal artery Vertebral artery Anterior segmental medullary arteries Ascending cervical artery

Cervical vertebrae

242

Deep cervical artery

Subclavian artery

Spinal branch Intercostal artery

Thoracic vertebrae Great anterior radicular artery (artery of Adamkiewicz) Intercostal artery Spinal branch

Lumbar artery

Lumbar vertebrae

Lateral (or median) sacral arteries Sacrum

FIG. 4.125  Anterior view of spinal arteries.

CHAPTER 4  Spine

Right lung

S

Anterior spinal artery

243

Left lung

L

R

Liver

I

Left kidney

FIG. 4.126  Coronal CT reformat with anterior spinal artery.

Great anterior radicular artery (artery of Adamkiewicz)

A

Vertebral body of L1

Lumbar segmental artery

R

L

P

Anterior spinal artery

FIG. 4.127  Axial CT with anterior spinal artery and great anterior radicular artery (artery of Adamkiewicz).

244

CHAPTER 4  Spine Anterior spinal artery Anterior central artery Nutrient vessels Posterior median sulcus Aorta Anterior radicular artery Intercostal artery (segmental artery) Posterior branch Posterior radicular artery Dorsal root ganglion

Posterior spinal arteries

Anterior branch Spinal nerve

Muscular branch

Posterior plexiform network

FIG. 4.128  Posterior oblique view of radicular arteries. Intercostal artery

Lung

S

Intervertebral foramen

Spinal muscles

A

Rib

P

Aorta

Vertebral body

I

FIG. 4.129  Coronal oblique CT reformat with aorta and intercostal artery.

CHAPTER 4  Spine

245

A

Aorta

Inferior vena cava

Lumbar (segmental) artery

Lumbar vertebra

R

L

P

FIG. 4.130  Axial CT of aorta and lumbar artery. S

Intercostal (segmental) artery Aorta

T12

Celiac trunk Superior mesenteric artery P

A Renal artery

Lumbar (segmental) artery

L5

I

FIG. 4.131  3D CT of lumbar spine, aorta, and segmental arteries, anterior oblique view.

246

CHAPTER 4  Spine

Spinal Veins Veins of the Spinal Cord.  The veins that drain the

spinal cord follow the same segmental organization as their arterial counterparts. The central gray matter of the cord is drained by the anterior and posterior central veins located in the anterior median fissure and posterior sulcus, respectively (Fig. 4.132). The outer white matter is drained by small radial veins that encircle the spinal cord within the pia mater. The venous blood collected by these tiny veins drains into the anterior and posterior median (spinal) veins created by the longitudinal venous channels within the pia mater on the anterior and posterior surfaces of the spinal cord (Fig. 4.132). The anterior and posterior median veins drain into the anterior and posterior radicular veins that parallel the ventral and dorsal nerve roots. They eventually empty into the intervertebral veins that accompany the spinal nerves through the intervertebral foramina.

Veins of the Vertebral Column.  The veins of

the vertebral column form an extensive network of internal and external venous plexuses, named according to their corresponding location in the vertebral column (Figs. 4.132–4.135). The internal venous plexuses lie within the vertebral canal in the epidural space and are

divided into anterior and posterior internal plexuses The valveless external venous plexuses communicate freely with the vertebral veins and intracranial venous sinuses and are located at the outer surfaces of the vertebral column. They can be divided into the anterior and posterior external plexuses. The anterior external venous plexuses run directly in front of the vertebral bodies, and the posterior external venous plexuses run along the posterior aspect of the vertebral arches (Fig. 4.133). The anterior sections of the internal and external plexuses communicate via a network of veins called the basivertebral veins, which drain the vertebral bodies. The large basivertebral veins emerge from the posterior surfaces of the vertebral bodies (Figs. 4.132, 4.133, 4.136, and 4.137). The internal and external venous plexuses, along with the radicular veins, drain into the intervertebral veins, ending in the vertebral, intercostal, lumbar, and sacral veins. Because the vertebral venous plexuses are valveless, an increase in intra-abdominal pressure (e.g., coughing, straining) may cause backflow of blood into the basivertebral veins of the spine or dural sinuses of the brain. This creates a potential pathway for metastatic disease or other pathology to spread to the central nervous system.

Anterior external vertebral venous plexus Basivertebral vein Anterior central vein

Anterior median (spinal) vein Anterior median fissure Anterior radicular vein

Intervertebral vein

Anterior internal vertebral venous plexus

Vertebral artery

Posterior internal vertebral venous plexus

Vertebral veins

Deep cervical vein

Posterior radicular vein

Radial veins Posterior median (spinal) veins

Posterior external venous plexus Posterior central vein

FIG. 4.132  Axial view of venous drainage of vertebral column and spinal cord.

CHAPTER 4  Spine

247

Basivertebral vein

Posterior external venous plexus

Anterior external venous plexus

Intervertebral disk Spinous process Vertebral body

Anterior internal venous plexus

Posterior internal venous plexus

FIG. 4.133  Sagittal view of venous plexuses of the spine. S

Conus medullaris

Cauda equina A

P

Posterior longitudinal ligament

Anterior internal venous plexus

Thecal sac Filum terminale I

FIG. 4.134  Sagittal, T2-weighted MRI of lumbar spine with anterior internal venous plexus.

248

CHAPTER 4  Spine A

Vertebral vein Vertebral artery Anterior internal venous plexus

Intervertebral vein R

L Cervical spinal cord

P

FIG. 4.135  Axial CT of cervical vertebra with anterior internal venous plexus.

Basivertebral vein

Psoas muscle

Thecal sac

Cauda equina

FIG. 4.136  Axial, T2-weighted MRI of lumbar vertebra with basivertebral vein.

CHAPTER 4  Spine

Psoas muscle

A

Vertebral body

249

Basivertebral vein

Contrast in intrathecal sac

R

L

P Cauda equina

FIG. 4.137  Axial CT of lumbar vertebra with basivertebral vein, post-myelogram.

REFERENCES Anderson, M. W., & Fox, M. G. (2017). Sectional anatomy by MRI and CT (4th ed.). Philadelphia: Elsevier. Frank, G. (2012). Merrill’s atlas of radiographic positions and radiologic procedures (12th ed.). St. Louis: Mosby. Haaga, J. R., & Boll, D. T. (2017). CT and MRI of the whole body (6th ed.). Philadelphia: Elsevier. Larsen, W. J. (2002). Anatomy: Development, function, clinical correlations. Philadelphia: Saunders. Palastanga, N. (2002). Anatomy and human movement: Structure and function (4th ed.). Boston: Butterworth-Heinemann.

Ross, J. S., & Moore, K. R. (2015). Diagnostic imaging: Spine (3rd ed.). Philadelphia: Elsevier. Som, P. M., & Curtin, H. D. (2011). Head and neck imaging (5th ed.). St. Louis: Elsevier. Standring, S. (2012). Gray’s anatomy, the anatomical basis of clinical practice (41st ed.). New York: Elsevier. Stark, D. D., & Bradley, W. G. (1999). Magnetic resonance imaging (3rd ed.). St. Louis: Mosby. Weir, J., & Abrahams, P. H. (2011). Imaging atlas of human anatomy (4th ed.). London: Elsevier.

CHAPTER

5

Neck A sharp tongue and a dull mind are usually found in the same head. Proverb

The neck is a region of considerable anatomic and functional complexity situated in a relatively small area. Recent advances in medical imaging have enhanced the ability to differentiate among the structures of the neck (Fig. 5.1).

FIG. 5.1  Coronal CT reformat demonstrating massive cervical lymphadenopathy.

OBJECTIVES • • • • • •

List the three anatomic sections of the pharynx. List and identify the laryngeal cartilages. Identify and describe the esophagus and trachea. Identify and state the function of the salivary glands. Describe the location and function of the thyroid gland. List the lymph node regions of the neck.

• Identify the fascial spaces. • Identify the pharyngeal muscles. • State the triangles of the neck, and identify the muscles located within them. • Describe the course of the major vessels located within the neck.

OUTLINE ORGANS, 251 Pharynx, 251 Larynx, 261 Esophagus and Trachea, 269 Salivary Glands, 271 Thyroid Gland, 277 Lymph Nodes, 280 250

Fascial Spaces, 283 MUSCLES, 294 Pharyngeal and Tongue Muscles, 294 Muscles Within the Anterior Triangle, 298

Copyright © 2019, Elsevier Inc.

Muscles Within the Posterior Triangle, 300 VASCULAR STRUCTURES, 302 Carotid Arteries, 302 Vertebral Arteries, 302 Jugular and Vertebral Veins, 308

CHAPTER 5  Neck

ORGANS The structures of the neck are attached by connective tissue and muscles. They are located primarily in the anterior and middle portions of the neck and include the pharynx, larynx, esophagus, trachea, salivary glands, thyroid gland, and lymph nodes.

Pharynx The pharynx is a funnel-shaped fibromuscular tube approximately 12 cm long that acts as an opening for both the respiratory and digestive systems. The pharynx extends from the base of the skull and ends inferiorly as the continuation of the esophagus. The pharynx is divided into three sections: nasopharynx, oropharynx, and laryngopharynx (Figs. 5.2–5.5). The nasopharynx is the most superior portion of the pharynx. It is an extension of the nasal cavities along with the nasal mucosa. The nasopharynx has a

251

respiratory function; it allows for the passage of air from the nasal cavity to the larynx. Posteriorly, the boundaries of the nasopharynx are the clivus and upper cervical spine. It is bordered inferiorly by the soft palate and the posterior muscular extension of the hard palate, and extends down to the level of the uvula, which is a projection on the posterior edge of the soft palate (Figs. 5.2–5.7). In the roof and posterior wall of the nasopharynx is a collection of lymphoid tissue known as the pharyngeal tonsils, commonly called the adenoids (Figs. 5.2–5.5). Within the lateral wall of the nasopharynx, posterior to the inferior nasal conchae, is the opening of the eustachian tube (auditory tube), which connects the middle ear to the nasopharynx (Fig. 5.2; see also Chapter 2, temporal bone). The oropharynx is the posterior extension of the oral cavity and extends from the soft palate to the level of the hyoid bone (Figs. 5.2, 5.4, 5.5, 5.8, and 5.9). It is separated from the larynx by the epiglottis. Two additional pairs of lymphoid tissue are found within the (Text continues on page 256)

Frontal sinus Nasal bone Sphenoid sinus

Nasal cartilage

Clivus

Inferior nasal concha

Pharyngeal tonsil

Hard palate

Opening for eustachian tube Nasopharynx

Oral cavity

Soft palate Uvula

Tongue

Palatine tonsil

Mandible

Oropharynx Epiglottis

Hyoid bone

Laryngopharynx

Lingual tonsil

Larynx

Vallecula Thyroid cartilage

Vestibular folds

True vocal folds

Cricoid cartilage Trachea

Esophagus

FIG. 5.2  Midsagittal view of the neck.

252

CHAPTER 5  Neck

Dorsum sellae

Clivus

Temporal bone

Mastoid process

Stylopharyngeus muscle

Pharyngeal tonsils

Posterior digastric muscle

NASOPHARYNX

Nasal septum Parotid gland

Eustachian tube Palatine tonsils

Soft palate OROPHARYNX

Medial pterygoid muscle

Submandibular gland

Valleculae

Uvula Lingual tonsils

Aryepiglottic fold

Tongue

Cuneiform cartilage

Epiglottis

Piriform sinus

LARYNGOPHARYNX

Corniculate cartilage Thyroid gland

Esophagus Trachea

Tracheal cartilages

FIG. 5.3  Posterior view of pharynx.

CHAPTER 5  Neck Soft palate

S

Clivus

Pharyngeal tonsils

Hard palate

Nasopharynx Tongue

Epiglottis

Oropharynx A

P

Valleculae Hyoid bone

Laryngopharynx

Thyroid cartilage

Cricoid cartilage

Esophagus

I

FIG. 5.4  Midsagittal, T2-weighted MRI of pharyngeal divisions.

Soft palate

S

Clivus

Pharyngeal tonsil Nasopharynx Hard palate

Uvula Oropharynx

Tongue Lingual tonsil

Laryngopharynx

Hyoid bone A

P Anterior longitudinal ligament

Valleculae Epiglottis

Cricoid cartilage

Thyroid cartilage Esophagus Thyroid gland Trachea I

FIG. 5.5  Sagittal CT reformat of pharynx.

253

CHAPTER 5  Neck

254

Masseter muscle

Medial pterygoid muscle

Hard palate

Nasopharynx

A

Ramus of mandible

Soft palate R

L

Longus capitis muscle

Parotid gland

Mastoid process

P

Odontoid process of C2

Lateral mass of C1

FIG. 5.6  Axial, T1-weighted MRI of nasopharynx. Medial pterygoid muscle

Hard palate

A

Uvula

Masseter muscle Parotid gland

Ramus of mandible

R

L

Longus capitis muscle Mastoid air cells Anterior arch of C1

Soft palate

Occipital bone

Odontoid process of C2

P

Nasopharynx

FIG. 5.7  Axial CT of nasopharynx.

Splenius capitis muscle

CHAPTER 5  Neck

Mandible

Mylohyoid muscle

A

Genioglossus muscle

Hyoglossus muscle Submandibular gland

Longus capitis muscle R

L

Oropharynx Palatopharyngeus muscle

Longus colli muscle

Sternocleidomastoid muscle

Semispinalis capitis muscle Splenius capitis muscle Trapezius muscle P

FIG. 5.8  Axial, T1-weighted MRI of oropharynx.

Genioglossus muscle

A

Mandible

Lingual tonsils

Mylohyoid muscle Palatopharyngeus muscle

Submandibular gland Longus colli muscle R

L

Sternocleidomastoid muscle

Oropharynx

P

FIG. 5.9  Axial CT of oropharynx.

255

256

CHAPTER 5  Neck

oropharynx: the palatine tonsils, which are located on the lateral walls, and the smaller lingual tonsils, which are situated on the base of the tongue (Figs. 5.2, 5.3, 5.5, and 5.9). Collectively, the tonsils initiate specific defense mechanisms of the immune system by protecting against pathogens entering the nasopharynx and oropharynx. At the union of the base of the tongue and the epiglottis are two pouchlike openings called valleculae. The valleculae are common sites for foreign objects to become lodged within the pharynx (Figs. 5.2–5.5 and 5.10–5.12).

Hyoid bone

A

The narrow laryngopharynx continues from the oropharynx and lies between the hyoid bone and the entrance to the larynx and esophagus (Figs. 5.2–5.5). It continues as the esophagus at the level of the cricoid cartilage of the larynx. Within the anterior walls of the laryngopharynx, along either side of the larynx, are two depressions or cavities termed the piriform sinuses (recesses). These sinuses divert food away from the entrance of the larynx and into the esophagus (Figs. 5.3 and 5.12–5.17). The laryngopharynx is commonly referred to as the hypopharynx.

Mandible

Valleculae

Digastric muscle

Submandibular gland

Submandibular gland R

L Epiglottis

Sternocleidomastoid muscle

Palatopharyngeus muscle

External jugular vein

Splenius capitis muscle

Levator scapulae muscle

Semispinalis capitis muscle

Trapezius muscle P

FIG. 5.10  Axial, T1-weighted MRI of valleculae.

CHAPTER 5  Neck

Valleculae

A

Hyoid bone

257

Epiglottis

Submandibular gland External carotid artery

Oropharynx

Facial vein Sternocleidomastoid muscle

External jugular vein R

L

Vertebral artery Internal jugular vein

Semispinalis cervicis muscle

P

Internal carotid artery

Semispinalis capitis muscle

FIG. 5.11  Axial CT of valleculae.

Nasopharynx S

Medial pterygoid muscle

Mandible Submandibular gland

Masseter muscle

Aryepiglottic fold

Vallecula Epiglottis R

L Arytenoid cartilage

Piriform sinus

Cricoid cartilage

Laryngopharynx

Thyroid cartilage

I

FIG. 5.12  Coronal, T1-weighted MRI of larynx.

Trachea

258

CHAPTER 5  Neck Maxillary sinus

Middle nasal concha S

Inferior nasal concha

Tongue

Masseter muscle

Hyoid bone

Mandible R

L Thyrohyoid muscle

Submandibular gland

Thyroid cartilage Aryepiglottic fold Laryngopharynx Platysma muscle

Arytenoid cartilage

Cricoid cartilage Trachea I

FIG. 5.13  Coronal, T1-weighted MRI of laryngopharynx.

Pituitary gland

Pharyngeal tonsil

S

Parotid gland

Temporal bone

Oropharynx Superior constrictor muscle

Ramus of mandible R

L Hyoid bone

Palatine tonsil

Piriform sinus

Laryngopharynx

Aryepiglottic fold Thyroid cartilage

Arytenoid cartilage

Thyroid gland Internal jugular vein

Cricoid cartilage

I

Trachea

FIG. 5.14  Coronal CT reformat of piriform sinuses.

CHAPTER 5  Neck Sphenoid sinus S

Ramus of mandible Oropharynx Palatine tonsil Parotid gland Digastric muscle Hyoid bone R Laryngopharynx

L Submandibular gland

Piriform sinus Epiglottis Arytenoid cartilage Thyroid cartilage Sternocleidomastoid muscle Thyroid gland

Internal jugular vein Common carotid artery

I Trachea

FIG. 5.15  Coronal CT reformat of epiglottis.

259

260

CHAPTER 5  Neck Thyrohyoid muscle

Sternohyoid muscle

A

Larynx

Platysma muscle Aryepiglottic fold

Thyroid cartilage

Piriform sinus

Inferior constrictor muscle Sternocleidomastoid muscle

External jugular vein R

L Longus capitis muscle

Internal jugular vein

Longus colli muscle

Internal carotid artery Levator scapulae muscle

Splenius capitis muscle

Semispinalis capitis muscle

Trapezius muscle

Semispinalis cervicis muscle P

FIG. 5.16  Axial, T1-weighted MRI of laryngopharynx. Sternohyoid and thyrohyoid muscles

Larynx

A

Thyroid cartilage

Aryepiglottic fold

Platysma muscle

Piriform sinus Common carotid artery

Sternocleidomastoid muscle

Internal jugular vein R

L

External jugular vein Retropharyngeal space

Longus capitis muscle

Levator scapulae muscle

Longus colli muscle

P

Inferior constrictor muscle

FIG. 5.17  Axial CT of laryngopharynx.

Trapezius muscle

CHAPTER 5  Neck

third to the sixth cervical vertebrae. These cartilages are connected to one another by ligaments and are moved by numerous muscles. Three of the cartilages are unpaired: the thyroid, epiglottis, and cricoid. The three paired cartilages are the arytenoid, corniculate, and cuneiform (Figs. 5.18–5.21). The largest and most superior is the thyroid cartilage. It consists of a right and left lamina that unite anteriorly to form a shield that protects the vocal cords (Figs. 5.16–5.20, 5.22, and 5.23). The

Larynx The larynx is the bony skeleton that surrounds and protects the vocal cords and is commonly called the voice box. It begins at the laryngopharynx, continues to the trachea, and marks the beginning of the respiratory pathway by allowing for the passage of air into the trachea. The larynx consists of an outer skeleton made up of nine cartilages that extend from approximately the

Hyoepiglottic ligament Hyoid bone

Thyrohyoid membrane

Epiglottis

Superior horn of thyroid cartilage

Thyroepiglottic ligament

Thyroid cartilage

Vestibular fold (false vocal cord)

Corniculate cartilage

Laryngeal prominence of thyroid cartilage A

Laryngeal ventricle P Arytenoid cartilage

True vocal cord

Cricoid cartilage Tracheal cartilages

FIG. 5.18  Sagittal view of larynx.

Superior thyroid notch Hyoid bone

Epiglottis Thyrohyoid membrane

Thyrohyoid ligament Thyroid cartilage

Superior horn of thyroid cartilage

Laryngeal prominence

Corniculate cartilage Cricoid cartilage

Cricothyroid ligament Inferior horn of thyroid cartilage

Arytenoid cartilage

Thyroid gland

Parathyroid gland Tracheal cartilage

Trachea $QWHULRUYLHZ

261

Membranous part of trachea 3RVWHULRUYLHZ

FIG. 5.19  Anterior and posterior views of larynx.

262

CHAPTER 5  Neck C1

Clivus

S

Hard palate Tongue Uvula

Anterior longitudinal ligament

Epiglottis A

P

Hyoid bone Superior vestibular folds Thyroid cartilage Inferior vestibular folds Cricoid cartilage Trachea

Laryngeal ventricle Arytenoid cartilage

I

Esophagus

FIG. 5.20  Sagittal, T1-weighted MRI of larynx.

Nasopharynx

S

Clivus

Pharyngeal tonsil C1 Tongue

Oropharynx Anterior longitudinal ligament

Valleculae Hyoid bone

Epiglottis A

P

Pre-epiglottic space

Laryngopharynx

Superior vestibular folds Thyroid cartilage Laryngeal ventricle Inferior vestibular folds

Cricoid cartilage

Cricoid cartilage

Esophagus

Thyroid gland

Trachea

I

FIG. 5.21  Sagittal CT reformat of larynx.

CHAPTER 5  Neck Glottis

A

263

True vocal cord Thyroid cartilage

Sternohyoid muscle Platysma muscle

Anterior jugular vein

Thyrohyoid muscle

Arytenoid cartilage

Cricoid cartilage External jugular vein

Sternocleidomastoid muscle R

L

Internal jugular vein

Inferior constrictor muscle

Common carotid artery Levator scapulae muscle

Posterior cricoarytenoid muscle

P

FIG. 5.22  Axial, T1-weighted MRI of neck with thyroid cartilage.

Aryepiglottic fold

Epiglottis

A

Thyroid cartilage Larynx

Aryepiglottic fold Piriform sinus Common carotid artery

Anterior jugular vein Superior thyroid artery

Internal jugular vein

Inferior constrictor muscle

Longus colli muscle

External jugular vein R

L Levator scapulae muscle

Sternocleidomastoid muscle

Trapezius muscle

P

FIG. 5.23  Axial CT of neck with thyroid cartilage.

Semispinalis capitis muscle

Splenius capitis muscle

264

CHAPTER 5  Neck

posterior aspect of the lamina has superior and inferior projections termed the superior and inferior horns (cornua), respectively. The anterior union of the lamina forms a vertical projection commonly referred to as the laryngeal prominence (Adam’s apple). Just above the laryngeal prominence is an area where the laminae do not meet, creating the superior thyroid notch. On the posterior aspect of this projection is the attachment for the epiglottis (Fig. 5.18). The leaf-shaped epiglottis differs from the other cartilages in that it is elastic and allows for movement. It is covered with a mucous membrane and projects superiorly and posteriorly behind the tongue. It is attached to the thyroid cartilage via the thyroepiglottic ligament and to the hyoid bone via the hyoepiglottic ligament. During swallowing, the epiglottis folds back over the larynx, preventing the entry of liquids or solid food into the respiratory passageways (Figs. 5.18–5.21, 5.24, and 5.25). The paired arytenoid cartilages are shaped like pyramids and are situated at the posterior aspect of the larynx just on top of the cricoid cartilage (Figs. 5.18, 5.19, 5.26, and 5.27). Articulating with the superior surface of the arytenoid cartilages are the small, elastic, horn-shaped corniculate cartilages (Figs. 5.18 and 5.19). These cartilages are involved in the movement of the vocal cords for the production of sound. The small, curved cuneiform cartilages lie within the folds of tissue termed the aryepiglottic folds that extend between the lateral aspect of the arytenoid cartilage and epiglottis (Figs. 5.3 and 5.30). The cricoid cartilage is a complete ring that forms the base of the larynx. The posterior portion is broader than the anterior portion, and this is where the other laryngeal cartilages rest. The cricoid cartilage marks the junction between the larynx and the trachea and the

beginning of the esophagus (Figs. 5.2, 5.12, 5.19–5.21, 5.28, and 5.29). Resultant swelling of the epiglottis caused by bacterial or viral infections can be very dangerous (acute epiglottitis). This condition can result in direct blockage of the glottis and airway, leading to suffocation and death.

The inner structures of the larynx include the false and true vocal cords and the aryepiglottic folds. The false and true vocal cords consist of two pairs of ligaments that extend from the arytenoid cartilages to the posterior laminal surface of the thyroid cartilage. They are separated by a space termed the laryngeal ventricle (Figs. 5.18, 5.20, and 5.21). The superior pair of ligaments is called the vestibular folds or false vocal cords because they are not directly involved in the production of sound. The inferior pair is the true vocal cords, named accordingly for their involvement in the production of sound (Figs. 5.18, 5.20, 5.21, 5.26, and 5.27). The true vocal cords extend toward the midline in a closed position during phonation. With quiet respiration, the true vocal cords are in a relaxed position, creating an opening between them called the glottis (Figs. 5.26, 5.27, 5.30, and 5.31). The glottis is the part of the larynx most directly involved with voice production. The aryepiglottic folds consist of tissue projecting off the arytenoid cartilages to the inferior margin of the epiglottis. These folds form the lateral margins of the entrance to the larynx. Located lateral to these folds, between the larynx and thyroid cartilage, are two mucosal pouches called the piriform sinuses whose medial borders form the lateral walls of the larynx (Figs. 5.3, 5.12, and 5.14–5.17).

CHAPTER 5  Neck

Valleculae

Geniohyoid muscle

Mylohyoid muscle

265

Thyroepiglottic ligament

A

Epiglottis

Submandibular gland

Palatopharyngeus muscle Middle constrictor muscle

External carotid artery R

L

Internal carotid artery Internal jugular vein

Sternocleidomastoid muscle

Vertebral artery

P

FIG. 5.24  Axial, T1-weighted MRI of neck with epiglottis. Mylohyoid muscle

Genioglossus muscle

A

Mandible

Epiglottic valleculae

Submandibular gland Hyoglossus muscle

External carotid artery

Lymph node level IIA

Internal carotid artery

R

L

Internal jugular vein

Sternocleidomastoid muscle

Pharyngeal constrictor muscle

Epiglottis

P

Oropharynx

FIG. 5.25  Axial CT of neck with epiglottis.

266

CHAPTER 5  Neck Arytenoid cartilage

A

Platysma muscle

Anterior jugular vein

Thyrohyoid muscle Sternohyoid muscle Thyroid cartilage

Sternocleidomastoid muscle

Cricoid cartilage

Glottis R

L Common carotid artery

True vocal cords

Internal jugular vein

Inferior constrictor muscle

Longus colli muscle

P

FIG. 5.26  Axial, T1-weighted MRI of larynx with vocal cords and arytenoid cartilages. Arytenoid cartilage

True vocal cord

Thyroid cartilage

Thyrohyoid muscle

A Anterior jugular vein

Sternocleidomastoid muscle Inferior constrictor muscle External jugular vein R

L

Internal jugular vein

Common carotid artery

Vertebral artery

P

Glottis

FIG. 5.27  Axial CT of larynx with vocal cords and arytenoid cartilages.

CHAPTER 5  Neck Sternohyoid muscle

267

Thyrohyoid muscle

A

Thyroid cartilage Sternocleidomastoid muscle

Cricoid cartilage

Thyroid gland

Internal jugular vein R

L Common carotid artery

Esophagus

P

FIG. 5.28  Axial, T1-weighted MRI of larynx with cricoid cartilage. Sternocleidomastoid muscle

Thyroid gland

Larynx

A

Cricoid cartilage

Esophagus

R

L Levator scapulae muscle Trapezius muscle

Internal jugular vein

Common carotid artery

P

FIG. 5.29  Axial CT of larynx with cricoid cartilage.

268

CHAPTER 5  Neck

Posterior aspect of tongue

Epiglottis

Aryepiglottic fold True vocal cords adducted

True vocal cords abducted Glottis

Vocalis muscle

Cuneiform cartilage

Corniculate cartilage Open

Closed

FIG. 5.30  Superior view of glottis in open and closed positions.

Thyroid cartilage

Hyoid bone

A

Vocal cord (closed)

Sternocleidomastoid muscle

R

L

Arytenoid cartilage

FIG. 5.31  Axial CT of larynx with closed vocal cords.

P

Superior horn of thyroid cartilage

CHAPTER 5  Neck

Esophagus and Trachea The esophagus is a muscular tube that extends down from the laryngopharynx to the cardiac orifice of the stomach (Figs. 5.32–5.34). It begins posterior to the cricoid cartilage and descends through the thoracic cavity between the trachea and anterior longitudinal ligament of the vertebrae (Figs. 5.20 and 5.21). The esophagus then enters the abdominal cavity through an opening in the diaphragm termed the esophageal hiatus to join the stomach (Fig. 5.32). There are two narrowed areas, or sphincters, of the esophagus: esophageal and cardiac. The esophageal sphincter is situated at the entrance of the esophagus and functions to prevent air from entering the esophagus. The inferior or cardiac sphincter prevents reflux from the stomach into the esophagus. The trachea extends from the larynx to the lungs and lies immediately

anterior to the esophagus (Figs. 5.2, 5.20, 5.21, and 5.32– 5.34). Considered an elastic tube, the trachea is reinforced by approximately 16–20 C-shaped pieces of cartilage that maintain an open passageway for air. The cartilages are closed posteriorly by elastic connective tissue that allows for the passage of food through the esophagus. The trachea bifurcates into the right and left mainstem bronchi at the carina, at approximately the T5 level.

The tracheostomy is currently one of the most frequently performed procedures and is one of the oldest surgical procedures described, dating back at least 3500 years. It is an operative procedure that creates a surgical airway in the trachea via an incision in the neck and insertion of a tracheostomy tube between the second and third tracheal rings.

Cricoid cartilage (posterior portion) Esophageal sphincter

Trachea

Aorta Right mainstem bronchus

Carina of trachea Left mainstem bronchus

Cardiac sphincter Esophagus

269

Esophageal hiatus Diaphragm Stomach

Cardiac orifice

FIG. 5.32  Anterior view of esophagus.

270

CHAPTER 5  Neck Trachea

A

Esophagus Internal jugular vein

Thyroid gland

Common carotid artery

External jugular vein

Anterior scalene muscle Middle scalene muscle

Vertebral body R

L Posterior scalene muscle

Levator scapulae muscle

Trapezius muscle

P

FIG. 5.33  Axial, T1-weighted MRI of esophagus and trachea. Thyroid gland

Trachea

A

Esophagus

Internal jugular vein

Sternocleidomastoid muscle

Common carotid artery

Scalene muscles

L

R Levator scapulae muscle

Trapezius muscle Vertebral body P

FIG. 5.34  Axial CT of esophagus and trachea.

CHAPTER 5  Neck

Salivary Glands The salivary glands are exocrine glands that collectively produce and empty saliva into the oral cavity via ducts. More than 750 minor salivary glands are scattered throughout the mouth and throat. They can be found in the mucosa of the oral cavity, palate, paranasal sinuses, pharynx, trachea, and bronchi. They consist of both mucous and serous glands that help with the total production of saliva. Up to a quart of saliva is produced each day to aid in the process of digestion. Saliva also helps protect the teeth from bacteria and moisten food for ease of swallowing. There are three large paired salivary glands: parotid, submandibular, and sublingual (Fig. 5.35). Each pair of salivary glands has a distinctive cellular organization and produces saliva with slightly different properties. The largest of these are the parotid glands, which are situated in front of the ear, wedged between the ramus of the mandible and the sternocleidomastoid muscle (Figs. 5.36–5.39). The parotid glands extend inferiorly from the level of the external auditory meatus to the angle of the mandible. Their appearance differs from that of the other salivary glands because of the fatty tissue and intraglandular lymph nodes they contain. The parotid duct (Stensen duct) emerges from the anterior

271

edge of the gland. It passes under the zygomatic arch to enter the oral cavity opposite the second upper molar (Figs. 5.36 and 5.37). The submandibular glands border the posterior half of the mandible, extending from the angle of the mandible to the level of the hyoid bone (Figs. 5.40–5.42). The submandibular duct (Wharton duct) opens into the oral cavity on either side of the lingual frenulum immediately posterior to the teeth (Fig. 5.43). The lingual frenulum is a small midline fold of mucous membrane that extends from the floor of the mouth to the undersurface of the tongue. The sublingual glands are the smallest of the salivary glands and lie under the tongue on the floor of the mouth (Figs. 5.43 and 5.44). Numerous (10–20) sublingual ducts (Rivinus ducts) open in a line along the floor of the mouth. Some of these ducts may fuse to form the Bartholin duct, which opens into or adjacent to the submandibular duct (Fig. 5.35).

The mumps virus often targets the salivary glands, most commonly the parotid gland. Infection usually occurs between 5 and 9 years of age. Because of the development of an effective mumps vaccine, the incidence of this disease has been dramatically reduced.

Parotid duct Parotid gland Auricle Tongue Lingual frenulum Masseter muscle

Sublingual ducts

Submandibular duct

Sublingual gland

Sternocleidomastoid muscle

Submandibular gland

FIG. 5.35  Lateral view of salivary glands.

272

CHAPTER 5  Neck Medial pterygoid Hard palate muscle

A

Soft palate

Mandible Parotid duct Masseter muscle

Superior constrictor muscle

R

L

Stylopharyngeus muscle

Odontoid process

Parotid gland Mastoid process

Retromandibular vein Internal carotid artery

Sternocleidomastoid muscle Internal jugular vein

P

FIG. 5.36  Axial, T1-weighted MRI of neck with parotid glands. Medial pterygoid muscle

A

Soft palate

Parotid duct Mandible

Masseter muscle

Retromandibular vein R

L

Parotid gland

Sternocleidomastoid muscle

P

FIG. 5.37  Axial CT of neck with parotid glands.

CHAPTER 5  Neck

Internal jugular vein

S

273

Upper internal jugular lymph nodes (IIA)

Parotid gland

Sternocleidomastoid muscle R

L

Vertebral artery

I

Vertebra

Brachial plexus

FIG. 5.38  Coronal, T1-weighted MRI of parotid glands.

Parotid gland

S

Clivus

C1

R

L

Sternocleidomastoid muscle

Internal jugular vein

I

FIG. 5.39  Coronal CT reformat of parotid glands.

C2

274

CHAPTER 5  Neck

Mandible

S

Masseter muscle Tongue Submandibular gland Suprahyoid muscle Hyoid bone R

L Thyroid cartilage

Infrahyoid muscle

Cricoid cartilage Sternocleidomastoid muscle

Thyroid gland

I

Clavicle

FIG. 5.40  Coronal, T1-weighted MRI of submandibular glands.

CHAPTER 5  Neck Mylohyoid muscle

Genioglossus muscle

A

Hyoglossus muscle

275

Platysma

Palatopharyngeus muscle

Submandibular lymph node (IB)

External carotid artery

Submandibular gland

Upper internal jugular lymph node (IIA)

External jugular vein

Internal carotid artery R

L

Oropharynx Upper internal jugular lymph node (IIA)

Internal jugular vein

Upper internal jugular lymph node (IIB) Sternocleidomastoid muscle

Levator scapulae muscle

Semispinalis capitis muscle

P

Splenius capitis muscle

Trapezius muscle

FIG. 5.41  Axial, T1-weighted MRI of neck with submandibular glands.

Lymph node level IIA

Tongue

A

Submandibular gland

External carotid artery Internal carotid artery

Platysma muscle

Internal jugular vein L

R

Sternocleidomastoid muscle

Oropharynx

Lymph node level IIB Semispinalis capitis muscle

P

Splenius capitis muscle

FIG. 5.42  Axial CT of neck with submandibular glands.

Trapezius muscle

CHAPTER 5  Neck

276

Mandible

Genioglossus muscle A

Sublingual gland

Mylohyoid muscle Wharton duct Submandibular gland

Hyoglossus muscle

External carotid artery R

L Retromandibular vein

Digastric muscle

Internal carotid artery

Internal jugular vein

P

FIG. 5.43  Axial, T1-weighted MRI of sublingual glands.

Genioglossus muscle A

Sublingual gland

Lingual vein

Hyoglossus muscle Submandibular gland

Mylohyoid muscle R

L External carotid artery Internal carotid artery

Internal jugular vein

P

FIG. 5.44  Axial CT of sublingual glands.

CHAPTER 5  Neck

Thyroid Gland

277

Thyroid nodules are abnormal growths of thyroid cells that form a lump within the thyroid gland. The majority of these nodules are benign, but they can also be cancerous in a small percentage of cases. The nodules can be solid or filled with fluid and are often discovered incidentally during a physical examination or on computed tomography (CT), magnetic resonance (MR), or ultrasound imaging. Most of the nodules are asymp­tomatic, but they can cause hyperthyroid or hypothyroid symptoms. A fine-needle aspiration may be used to take a biopsy of the cells in the nodule to determine if the nodule is cancerous. The majority of benign thyroid nodules do not require treatment.

The thyroid gland is an endocrine gland located at the level of the cricoid cartilage. It consists of two lobes that are joined together anteriorly by the isthmus (Figs. 5.45 and 5.46). In the axial plane, the thyroid gland appears as a wedge-shaped structure, hugging both sides of the trachea (Figs. 5.47 and 5.48). The thyroid gland excretes the hormones thyroxine (T4), triiodothyronine (T3), and calcitonin, which affect almost every cell in the body. Thyroxine and triiodothyronine stimulate cell metabolism and are essential for normal body growth. Calcitonin lowers the blood calcium level and promotes bone formation. Also involved with metabolism of calcium and phosphorus are the parathyroid hormones (PTHs), which are produced by the parathyroid glands. The parathyroid glands are located on the posterior surface of the thyroid lobes and are usually four in number (Fig. 5.45).

Hypothyroidism is an underproduction of the thyroid hormone. The most common form is an autoimmune disease called Hashimoto’s thyroiditis, also known as chronic lymphocytic thyroiditis or autoimmune thyroiditis. In Hashimoto’s thyroiditis, the body sees the thyroid gland as foreign and attacks it. Symptoms include fatigue, sensitivity to cold, excess weight gain, poor circulation, dry skin, hair loss, depression, and poor digestion.

S Hyoid bone Common carotid artery

Common carotid artery

Internal jugular vein

Internal jugular vein Superior thyroid artery

Thyroid cartilage

Isthmus of thyroid gland

Cricoid cartilage

Parathyroid glands R

L

Parathyroid glands

Thyroid gland Tracheal cartilage

Subclavian artery

Subclavian vein

Brachiocephalic trunk

Subclavian artery Aortic arch

Superior vena cava

I

FIG. 5.45  Anterior view of thyroid gland.

278

CHAPTER 5  Neck

Ramus of mandible

Oropharynx

Epiglottis

S

Arytenoid cartilage

Internal carotid artery

Parotid gland

External carotid artery

Upper internal jugular lymph node (IIA) Sternocleidomastoid muscle R

L Thyroid cartilage

Laryngopharynx

Cricoid cartilage Thyroid gland

Right internal jugular vein

Left internal jugular vein Larynx

Brachiocephalic trunk

I

Aortic arch

FIG. 5.46  Coronal CT reformat of thyroid gland.

Trachea

CHAPTER 5  Neck Internal jugular vein

Common carotid artery

A

279

Isthmus of thyroid gland Sternohyoid muscle

Sternocleidomastoid muscle

Sternothyroid muscle

External jugular vein

Left lobe of thyroid gland Trachea

Esophagus L

R

P

FIG. 5.47  Axial, T1-weighted MRI of thyroid gland.

Inferior thyroid artery

Trachea

Tracheal cartilage

Common carotid artery

A

Isthmus of thyroid gland

Left lobe of thyroid gland Low jugular lymph node (IV)

Internal jugular vein

Esophagus

External jugular vein L

R

P

FIG. 5.48  Axial CT of thyroid gland.

Vertebral artery

280

CHAPTER 5  Neck foreign particles before being emptied into the venous blood supply. In the head and neck, lymph nodes are grouped along the lower border of the jaw, in front of and behind the ears, and deep in the neck along the larger blood vessels (Figs. 5.49 and 5.50). They drain the skin of the scalp and face, tissues of the nasal cavity, oral cavity, pharynx, trachea, upper esophagus, thyroid gland, and salivary glands. The lymph nodes of the neck can be classified or divided into seven levels or regions for ease of identification, both clinically and surgically (Figs. 5.25, 5.42, and 5.49–5.51 and Table 5.1).

Lymph Nodes The neck has an extensive lymphatic network containing approximately 40% of the body’s total number of lymph nodes. It is estimated that there are 800 lymph nodes located throughout the body, and roughly 300 of these are located in the relatively small area of the head and neck. Lymph nodes are clustered in regions throughout the vessels of the lymphatic system. The lymph vessels carry fluid from the interstitial spaces to the regional lymph nodes, which filter the lymphatic fluid of harmful

Facial nodes (1–4)

Parotid nodes (3–6)

Buccal nodes (1–3) Level IA submental nodes (1–8)

Mastoid nodes (3–10) Occipital nodes (1–4)

Level IB submandibular (submaxillary) nodes (3–6)

Level V spinal accessory (posterior triangle) nodes (4–20)

Levels II, III, and IV internal jugular (deep cervical) nodal chain (15–40)

Supraclavicular (transverse cervical nodes) (1–10)

Level VI juxtavisceral (visceral) nodes (6–16) Anterior jugular nodal chain (1–4) Posterior boundary of submandibular gland

IB Lower border of hyoid

Jugular fossa

IIA

IA

IIB

Lower margin of cricoid cartilage

III VA VB

VI IV Right common carotid artery Top manubrium

VII

Internal jugular vein

FIG. 5.49  Top, Oblique view of lymph nodes in the head and neck. Bottom, Regional classification of lymph nodes of the neck.

CHAPTER 5  Neck

Submandibular gland

S

Posterior triangle lymph nodes (VA)

Submandibular lymph node (IB)

A

P Posterior triangle lymph nodes (VB)

Sternocleidomastoid muscle

Middle scalene muscle

Anterior scalene muscle

I

Subclavian artery

FIG. 5.50  Sagittal, T1-weighted MRI of lymph nodes.

281

282

CHAPTER 5  Neck Digastric muscle (anterior belly)

Mandible

IA

IB

IB

External carotid artery

Submandibular gland

Internal carotid artery

IIA IIA

Sternocleidomastoid muscle

IIB IIB

Internal jugular vein

FIG. 5.51  Axial CT of neck with abnormal lymph nodes identified by level.

TABLE 5.1

Imaging-Based Classification of Neck Lymph Node Levels

Node

Location

Level I Submental and Submandibular Nodes Level IA Submental nodes Level IB Submandibular nodes Level II Upper Internal Jugular Nodes

Located above the hyoid bone and the body of the mandible and in front of the posterior boundary of the submandibular gland Between the medial margins of the anterior bellies of the digastric muscles Lateral to the level IA nodes and anterior to the back of the submandibular gland Upper third of the internal jugular vein Extend from the skull base to the level of the hyoid bone Located posterior to the submandibular gland and bounded posteriorly by the sternocleidomastoid (SCM) muscle A level II node that lies medial, lateral, anterior, or posterior to the internal jugular vein A level II node that lies posterior to the internal jugular vein and is separated by a fat plane Extend from the carotid bifurcation or hyoid bone inferiorly to the cricoid cartilage Lie anterior to the SCM muscle Extend from the bottom of the cricoid to the level of the clavicle Lie lateral to the carotid arteries Bordered anteriorly by the SCM muscle, posteriorly by the trapezius muscle, and inferiorly by the clavicle Upper level V nodes that extend inferiorly from the skull base to the cricoid cartilage Lower level V nodes that extend from the bottom of the cricoid cartilage to the clavicle Extend from the hyoid bone to the top of the manubrium Lie between the carotid arteries Extend from the top of the manubrium to the brachiocephalic vein, between the carotid arteries Nodes at or caudal to the clavicle and lateral to the carotid artery Nodes behind the pharynx Extend medial to the internal carotid artery from the base of the skull inferiorly to the hyoid bone

Level IIA Level IIB Level III Midjugular Nodes Level IV Low Jugular Nodes Level V Posterior Triangle Nodes Level VA Level VB Level VI Upper Visceral Nodes Level VII Superior Mediastinal Nodes Supraclavicular nodes Retropharyngeal nodes

CHAPTER 5  Neck

Fascial Spaces Structures located in the neck can be divided into supra- and infrahyoid structures based on their location in relation to the hyoid bone. The horseshoe-shaped hyoid bone lies in the anterior aspect of the neck superior to the thyroid cartilage and below the mandible; it forms a base for the tongue (Figs. 5.2, 5.11, 5.19, and 5.20). The suprahyoid neck extends from the base of the skull to the hyoid bone, and the infrahyoid neck extends from the hyoid bone to the clavicles. The suprahyoid and infrahyoid regions of the neck are further divided by deep layers of cervical fascia that encase the anatomy of each region, forming compartments or potential spaces called fascial spaces. There are seven suprahyoid spaces, one infrahyoid space, and four spaces that span the length of the neck to include both the supra- and infrahyoid regions, as follows: SUPRAHYOID NECK • Parapharyngeal space (PPS) • Pharyngeal mucosal space (PMS) • Masticator space (MS) • Parotid space (PS) Perivertebral space and prevertebral space

Masticator space

• Carotid space (CS) • Retropharyngeal space (RPS), including the danger space (DS) • Perivertebral space (PVS), including the prevertebral and paraspinal spaces INFRAHYOID NECK • Visceral space (VS) SUPRA- and INFRAHYOID NECK • Carotid space (CS) • Retropharyngeal space (RPS) • Perivertebral space (PVS) • Posterior cervical space (PCS) Each compartment or space is associated with pathology specific to the anatomic structures contained within it. Knowledge of the anatomy in these compartments improves the ability to predict the spread of pathology throughout the soft tissue structures in the neck and aids in their surgical intervention (Figs. 5.52–5.55). The fascial spaces can be identified on the sequential images in Figs. 5.53–5.69 and are described in more depth in Table 5.2. Retropharyngeal space and danger space

Masticator space

Parapharyngeal space and carotid sheath Parotid space Retrovisceral space Submandibular space Visceral space

Parapharyngeal space and carotid sheath

Pretracheal space

283

Retropharyngeal space and danger space

Parapharyngeal space and carotid sheath

Retropharyngeal space and danger space Perivertebral space and prevertebral space

FIG. 5.52  Oblique view of fascial planes and spaces of the neck.

284

CHAPTER 5  Neck Nasal septum Maxilla

Medial pterygoid muscle Lateral pterygoid muscle Temporalis muscle Masseter muscle Tensor veli palatini muscle Eustachian tube

Masticator space

Levator veli palatini muscle

Parapharyngeal space

Mandibular ramus Parotid gland

DLDCF-alar fascia

Styloid process

Parotid space

Posterior belly of the digastric muscle Mastoid process

Glossopharyngeal nerve

Internal carotid artery and internal jugular vein DLDCF

Vagus nerve Sternocleidomastoid muscle

SLDCF

Longus colli muscle and longus capitis muscle

Inferior oblique capitis muscle

C1 Semispinalis capitis muscle

Skin Trapezius muscle

FIG. 5.53  Axial view of neck at level of C1. DLDCF, Deep layer, deep cervical fascia; SLDCF, superficial layer, deep cervical fascia.

CHAPTER 5  Neck SLDCF MLDCF

Thyrohyoid muscle

Visceral space

Sternohyoid muscle Thyroid cartilage Inferior pharyngeal constrictor muscle

Sternothyroid muscle SCF and platysma muscle

Sternocleidomastoid muscle Internal jugular vein and common carotid artery

Carotid sheath

Vagus nerve

DLDCF-alar fascia

Retropharyngeal space - danger space

Perivertebral space - prevertebral space

Phrenic nerve

Middle scalene muscle

Longus capitis muscle, longus colli muscle, anterior scalene muscle

Multifidus muscle

C4

SLDCF

Semispinalis capitis muscle

Levator scapulae muscle

Splenius capitis muscle

DLDCF Perivertebral space - paraspinal portion

Trapezius muscle Ligamentum nuchae

Semispinalis cervicis muscle

FIG. 5.54  Axial view of neck at level of C4. DLDCF, Deep layer, deep cervical fascia; MLDCF, middle layer, deep cervical fascia; SCF, superficial cervical fascia; SLDCF, superficial layer, deep cervical fascia.

MLDCF SCF and platysma muscle

Trachea

Sternohyoid muscle Esophagus Sternothyroid muscle

Visceral space

Thyroid gland

Carotid space

Sternocleidomastoid muscle

DLDCF-alar fascia

Internal jugular vein and common carotid artery

Retropharyngeal space - danger space

Vagus nerve

Posterior and middle scalene muscles

Phrenic nerve Longus capitis muscle, longus colli muscle, anterior scalene muscle Vertebral artery and veins

DLDCF

C7

Multifidus muscle SLDCF

Trapezius muscle

Spinalis cervicis muscle Semispinalis cervicis muscle

Splenius capitis muscle

Ligamentum nuchae

FIG. 5.55  Axial view of neck at level of C7. DLDCF, deep layer, Deep cervical fascia; MLDCF, middle layer, deep cervical fascia; SCF, superficial cervical fascia; SLDCF, superficial layer, deep cervical fascia.

285

CHAPTER 5  Neck

286

Parotid duct

Anterior facial vein

A

Superior constrictor muscle

Masseter muscle

Longus capitis muscle

Masticator space

Parapharyngeal space Retromandibular vein

Mandible R

L

Parotid gland Medial pterygoid muscle

Internal carotid artery

Upper internal jugular lymph node (IIA)

Internal jugular vein

Mastoid process

Odontoid process P

Sternocleidomastoid muscle

FIG. 5.56  Axial, T1-weighted MRI of neck with parotid glands.

Ascending pharyngeal artery

Temporalis muscle

A

Parapharyngeal space

Nasopharynx

Medial pterygoid muscle Lateral pterygoid muscle

Internal carotid artery

Masseter muscle Masticator space

Condyloid process of mandible (condyle)

Retromandibular vein R

L Parotid gland

Internal jugular vein

Longus capitis muscle

Splenius capitis muscle

Rectus capitis anterior muscle Right vertebral artery

Semispinalis capitis muscle

P

Left vertebral artery

FIG. 5.57  Axial CT of neck with parotid glands.

CHAPTER 5  Neck Mylohyoid muscle

Hypoglossus muscle

A

Genioglossus muscle

287

Oropharynx Inferior constrictor muscle

External carotid artery

Retromandibular vein

Internal carotid artery

Upper internal jugular lymph node (IIA) R

L Longus capitis muscle Perivertebral space - prevertebral portion - paraspinal portion

Internal jugular vein Upper internal jugular lymph node (IIB)

Sternocleidomastoid muscle

P

Vertebral artery

Longus colli muscle

FIG. 5.58  Axial, T1-weighted MRI of neck with oropharynx.

Masseter muscle

Pterygoid hamulus of Anterior sphenoid Hard facial vein bone palate Oropharynx A

Buccinator muscle Pharyngeal mucosal space

Medial pterygoid muscle

Palatopharyngeal muscle

External carotid artery

Parapharyngeal space

Retromandibular vein

Longus capitis muscle

Parotid space R

L

Styloid process

Parotid gland

Internal jugular vein Rectus capitis muscle

SCM

Splenius capitis muscle

Posterior belly of digastric muscle Internal Right Pharyngeal carotid vertebral constrictor artery artery muscle

P

Semispinalis capitis muscle

FIG. 5.59  Axial CT of neck with oropharynx.

Longissimus capitis muscle

288

CHAPTER 5  Neck Hyoglossus muscle

A Genioglossus muscle

Submandibular lymph node (IB)

Masseter muscle

Palatine tonsil

Pharyngeal mucosal space

External carotid artery Retromandibular vein R

L

Parotid space

Sternocleidomastoid muscle

Digastric muscle

Internal jugular vein

Longus colli muscle

Upper internal jugular lymph node (IIB)

Upper posterior triangle lymph node (VA)

P

Internal carotid artery

FIG. 5.60  Axial, T1-weighted MRI of neck with enlarged palantine tonsils.

Superior constrictor muscle

Genioglossus muscle

External carotid artery

A

Uvula

Palatine tonsil

Buccinator muscle Medial pterygoid muscle Masseter muscle

Internal carotid artery

Longus capitis muscle

Retromandibular vein

Upper internal jugular vein lymph node (IIA)

Perivertebral space - prevertebral portion - paraspinal portion

Posterior belly of digastric muscle R

L

Parotid space Parotid gland

External jugular vein

Sternocleidomastoid muscle

Internal jugular vein

Semispinalis cervicis

Upper internal jugular vein lymph node (IIB)

Splenius capitus muscle

Levator scapulae muscle

Semispinalis capitis muscle Vertebral artery

Occipital artery

P

Trapezius muscle

FIG. 5.61  Axial CT of neck with uvula.

CHAPTER 5  Neck

289

A Body of mandible Genioglossus muscle

Submandibular gland Platysma muscle

Valleculae

Internal carotid artery Digastric muscle posterior belly Upper internal jugular lymph node (IIA)

Epiglottis R

L Internal jugular vein

External jugular vein

Sternocleidomastoid muscle

Longus capitis and longus colli muscles

Upper internal jugular lymph node (IIB)

Vertebral artery Levator scapulae muscle

Posterior triangle lymph node (VA)

Retropharyngeal space P

Trapezius Semispinalis capitis muscle muscle

Splenius capitis muscle

FIG. 5.62  Axial, T1-weighted MRI of neck with epiglottis.

Anterior facial Platysma vein muscle

Sublingual vein

A

Genioglossus muscle

Hyoglossus muscle

Submandibular gland

Mylohyoid muscle Epiglottis

External carotid artery

Facial artery External carotid artery

Upper internal jugular lymph node (IIA)

Facial vein

Internal carotid artery External jugular vein

Upper internal jugular lymph node (IIA) Internal carotid artery R

L

Internal jugular vein

External jugular vein Sternocleidomastoid muscle

Pharyngeal constrictor muscle

Upper posterior triangle lymph node (VA)

Longus colli muscle

Posterior cervical space

Trapezius muscle

Posterior scalene muscle Semispinalis cervicis muscle

Splenius capitis muscle

P

Semispinalis capitis muscle

FIG. 5.63  Axial CT of neck with epiglottis.

Levator scapulae muscle

290

CHAPTER 5  Neck

Sternohyoid Thyrohyoid muscle muscle A

Inferior constrictor muscle Common carotid artery Midjugular lymph node (III)

Hyoid bone Submandibular gland

Internal jugular vein

Sternocleidomastoid muscle

External jugular vein

R

L Retropharyngeal space - danger space

Carotid space Midjugular lymph node (III)

Longus colli muscle Posterior cervical space P

FIG. 5.64  Axial, T1-weighted MRI of neck with hyoid bone.

Mylohyoid muscle

A

Anterior belly of digastric muscle

Hyoid bone Anterior jugular vein

Platysma muscle Submandibular gland

Superior cornu of thyroid cartilage

Inferior constrictor muscle

Common carotid artery

Sternocleidomastoid muscle R

L Carotid space

External jugular vein

Lymph node level IIB Internal jugular vein

Levator scapulae muscle

Scalene muscles

Trapezius muscle

Vertebral artery Splenius capitis muscle

Semispinalis capitis muscle

P

Semispinalis cervicis muscle

FIG. 5.65  Axial CT of neck with hyoid bone.

CHAPTER 5  Neck

Common carotid artery

Platysma

Arytenoid cartilage

A

Visceral Sternohyoid Vocal space muscle cords

Omohyoid muscle Thyroid cartilage Thyrohyoid muscle

Sternocleidomastoid muscle

Anterior jugular vein Midjugular lymph nodes (III)

External jugular vein

L

R

Inferior constrictor muscle

Levator scapulae muscle

Retropharyngeal space - danger space Trapezius muscle

Internal jugular vein

P

Longus capitis muscle

Vertebral artery

FIG. 5.66  Axial, T1-weighted MRI of neck with thyroid cartilage.

291

CHAPTER 5  Neck

292

Thyroid cartilage

Anterior jugular vein

Cricoid cartilage

A

Visceral space

Inferior constrictor muscle

Midjugular lymph node (III)

Omohyoid muscle

Retropharyngeal space – danger space

Sternocleidomastoid muscle

External jugular vein Anterior and middle scalene muscles

Internal jugular vein

R

L Common carotid artery

Levator scapulae muscle

Longus colli muscle

Splenius capitis muscle

Vertebral artery Semispinalis capitis muscle

P

Multifidus muscle

Trapezius muscle

FIG. 5.67  Axial CT of neck with thyroid cartilage.

Sternothyroid muscle

Sternohyoid muscle Trachea A

Visceral space Esophagus

Upper visceral lymph node (VI)

Sternocleidomastoid muscle

Internal jugular vein

Thyroid gland

Common carotid artery

Low jugular lymph node (IV)

Anterior scalene muscle

Longus capitis muscle R

L

Middle scalene muscle Posterior scalene muscle

Levator scapulae muscle

Spinal cord Prevertebral space -paraspinal portion P

Vertebral artery

FIG. 5.68  Axial, T1-weighted MRI of neck with thyroid gland.

CHAPTER 5  Neck Sternocleidomastoid Anterior muscle jugular vein

Trachea

Low jugular lymph node (IV)

Sternohyoid and sternothyroid muscles A

Thyroid gland

293

Internal jugular vein

Common carotid artery Anterior scalene muscle

External jugular vein

Lower posterior triangle lymph node (VB)

Esophagus

Posterior cervical space Middle scalene muscle

R Levator scapulae muscle

L Posterior scalene muscle Vertebral artery and vein

Trapezius muscle

Splenius capitis muscle

Erector spinae muscles

P

Longus capitis muscle

Upper visceral lymph node (IV)

FIG. 5.69  Axial CT of neck with thyroid gland.

TABLE 5.2 Space

Suprahyoid and Infrahyoid Neck Spaces and Contents Contents

SPACES IN SUPRAHYOID NECK Parapharyngeal Fat, minor salivary glands, and a portion of the pterygoid venous plexus Pharyngeal Mucosal Mucosal surface of pharynx; pharyngeal, palatine, and lingual tonsils; submucosal minor salivary glands Masticator Posterior body and ramus of mandible; masseter, temporalis, medial, and lateral pterygoid muscles; mandibular branch of the trigeminal nerve (Cranial Nerve V3) Parotid Parotid gland; facial nerve (CN VII); branches of external carotid arteries; intraparotid lymph nodes Carotid Suprahyoid: Internal carotid artery, internal jugular vein, and cranial nerves 9 through 12 (CN IX–XII) Infrahyoid: Common carotid artery, internal jugular vein, and trunk of the vagus nerve (CN X) Retropharyngeal • Danger Medial and lateral retropharyngeal lymph nodes and fat Perivertebral • Prevertebral Cervical vertebral body and intervertebral disk; muscles: longus colli, longus capitus, scalene; vertebral artery and vein; brachial plexus; phrenic nerve • Paraspinal Posterior elements of cervical vertebrae; paraspinal muscles SPACES IN SUPRA- AND INFRAHYOID NECK Carotid See above Retropharyngeal See above Perivertebral See above Posterior Cervical Fat; spinal accessory lymph nodes; accessory nerve (CN XI) SPACE IN INFRAHYOID NECK Visceral Thyroid and parathyroid glands; esophagus; paratracheal nodes; recurrent laryngeal nerve; larynx and trachea

294

CHAPTER 5  Neck

MUSCLES Numerous muscles are located within the neck. Each muscle can be difficult to identify individually because the margins seem to blend together in cross-sectional images. This section of the text addresses only the largest and most significant muscles of the neck region.

Pharyngeal and Tongue Muscles The pharyngeal muscles include the circular layer of constrictors and the inner longitudinal layers (Table 5.3).

TABLE 5.3

Pharyngeal Muscles

Pharyngeal Muscles

Origin

External (Circular) Muscles Superior constrictors

• Pterygoid hamulus; posterior end of mandible; side of tongue • Stylohyoid ligament, hyoid Middle constrictors bone • Sides of thyroid and cricoid Inferior constrictors cartilages Longitudinal (Internal) Muscles Stylopharyngeus • Mental spine of mandible Palatopharyngeus

• Hard palate; palatine aponeurosis

Salpingopharyngeus

• Cartilaginous part of auditory tube

Tongue Muscles Genioglossus Hyoglossus Styloglossus Palatoglossus

There are three overlapping constrictor muscles (superior, middle, inferior) that are responsible for constricting the pharynx and inducing peristaltic waves during swallowing. The three inner longitudinal muscles are the stylopharyngeus, palatopharyngeus, and salpingopharyngeus muscles, all involved with elevating the pharynx and larynx during swallowing and speaking (Figs. 5.71–5.74). The extrinsic muscles of the tongue are responsible for changing the position of the tongue and include the genioglossus, hyoglossus, styloglossus, and palatoglossus muscles (Figs. 5.70–5.76).

• Mental spine of mandible • Greater horn and body of hyoid bone • Styloid process of temporal bone • Oral surface of palatine aponeurosis

Insertion

Action

• Pharyngeal tubercle; occipital bone; median raphe of pharynx • Median raphe of pharynx

All constrict pharynx, induce peristaltic waves during swallowing

• Median raphe of pharynx • Posterior/superior borders of thyroid cartilage • Side of pharynx and esophagus, posterior border of thyroid cartilage • Blends with palatopharyngeus muscle

All elevate pharynx and larynx during swallowing and speaking

• Ventral surface of tongue; anterior hyoid bone • Lateral aspect of tongue base

• Moves tongue forward

• Lateral margin of tongue

• Moves tongue upward and backward • Elevates posterior tongue

• Side and dorsum of tongue

• Moves tongue backward

CHAPTER 5  Neck

Tensor veli palatini Levator veli palatini Pterygoid hamulus

Stylohyoid ligament

Transverse process of atlas Buccinator (cut) Vertebral artery

Stylopharyngeus

Genioglossus Geniohyoid

Stylohyoid Middle constrictor

Superior constrictor Inferior constrictor

Styloglossus Hyoglossus Hyoid bone Thyrohyoid membrane Thyroid cartilage

Cricothyroid

FIG. 5.70  Sagittal view of pharyngeal and tongue muscles.

295

CHAPTER 5  Neck

296

Oropharynx

A

Palatine tonsil

Ramus of mandible Masseter muscle

Palatopharyngeus muscle

Medial pterygoid muscle

Stylohyoid muscle

Superior constrictor muscle

External carotid artery R

L Parotid gland

Digastric muscle (posterior belly)

Longus capitis muscle

Internal jugular vein

Longus colli muscle

Internal carotid artery P

Stylopharyngeus muscle

Oblique capitis inferior muscle

Sternocleidomastoid muscle

FIG. 5.71  Axial, T1-weighted MRI of pharyngeal muscles.

Genioglossus muscle

A

Mandible

Mylohyoid muscle Hyoglossus muscle R

L

Lingual tonsil

Palatopharyngeus muscle Middle constrictor muscle

Oropharynx

Superior constrictor muscle

Longus colli muscle

Longus capitis muscle P

FIG. 5.72  Axial CT of pharyngeal muscles.

CHAPTER 5  Neck Hard palate

Uvula

S

Pharyngeal tonsils

Genioglossus muscle Sublingual gland

Epiglottis

Geniohyoid muscle

Inferior constrictor muscle

Mylohyoid muscle

Arytenoid cartilage

Hyoid bone Submental lymph node (IA) A

P

Superior vestibular fold

Cricoid cartilage

Laryngeal ventricle Thyroid cartilage

Esophagus

Sternothyroid muscle Thyroid gland Superior mediastinal lymph node (VII)

I

FIG. 5.73  Sagittal, T1-weighted MRI of pharyngeal muscles. S

Soft palate Tongue Genioglossus muscle Lingual artery

Oropharynx

Geniohyoid muscle A

P

Hyoid bone

Inferior constrictor muscle

Mylohyoid muscle Thyroid cartilage

Arytenoid cartilage

Sternothyroid muscle Thyroid gland

I

FIG. 5.74  Sagittal CT reformat of pharyngeal muscles.

297

298

CHAPTER 5  Neck

Hyoglossus

Styloglossus

Submandibular duct S

Lingual vein Lingual artery

Buccinator

Sublingual gland, posterior pole

Genioglossus Mandibular canal

R

L Lingual nerve

Mylohyoid

Facial artery Geniohyoid

I

Anterior belly of digastric

Submandibular gland, deep part Platysma

FIG. 5.75  Coronal view of tongue muscles. Hyoglossus

S

Genioglossus

Masseter

Geniohyoid

Styloglossus

Mylohyoid R

L Lingual vein Lingual artery Platysma

Digastric muscle (anterior belly)

I

FIG. 5.76  Coronal, T1-weighted MRI of tongue muscles.

Muscles Within the Anterior Triangle The neck is frequently divided into two areas called the anterior and posterior triangles by the sternocleidomastoid (SCM) muscle. Everything anteromedial to the SCM muscle is considered part of the anterior triangle, and everything posterior to the SCM muscle is considered part of the posterior triangle. The SCM muscle is a broad, straplike muscle that originates on the sternum and clavicle and inserts on the mastoid tip of the temporal bone. It functions to turn the head from side to side and flex the neck (Figs. 5.77 and 5.78) The platysma is the most superficial muscle found in the anterior portion of the neck. It arises from the fascia and skin overlying the pectoralis major and deltoid muscles and extends superiorly as a thin, broad muscle to the inferior portion of the mandible. It is considered a chief muscle for facial expression (Figs. 5.62, 5.63, and 5.80).

Other muscles of the anterior triangle are referred to as the muscles of the throat and can be divided into the suprahyoid and infrahyoid muscle groups (Figs. 5.77 and 5.78). These muscle groups are named according to their location in relation to the hyoid bone. The suprahyoid and infrahyoid muscles aid in the movement of the hyoid bone and larynx. The suprahyoid muscles (digastric, mylohyoid, stylohyoid, geniohyoid) connect the hyoid bone to the temporal bone and mandible and elevate the hyoid and floor of the mouth and tongue during swallowing and speaking (Figs. 5.70, 5.75, 5.76, and 5.78). The infrahyoid muscles (thyrohyoid, sternohyoid, sternothyroid, omohyoid) are often called strap muscles because of their ribbon-like appearance (Fig. 5.78). They act primarily to depress the hyoid bone and extend inferiorly to insert on the sternum, thyroid cartilage, and scapula (Table 5.4; see sequential images in Figs. 5.52–5.69).

CHAPTER 5  Neck

Temporalis

Splenius capitis Levator scapulae Masseter Middle scalene Buccinator

Trapezius Sternocleidomastoid

Platysma (cut)

Anterior scalene

Omohyoid (superior belly)

Omohyoid (inferior belly)

Thyrohyoid Sternohyoid

FIG. 5.77  Lateral view of sternocleidomastoid muscle and neck muscles within the anterior and posterior triangles.

Digastric Styloglossus

Splenius capitis

Stylohyoid Mylohyoid

Hyoglossus Longus capitis

Hyoid bone Sternocleidomastoid

Levator scapulae Sternohyoid

Omohyoid Trapezius Middle scalene

Cricothyroid

Posterior scalene Anterior scalene Sternothyroid

FIG. 5.78  Anterior view of suprahyoid and infrahyoid neck muscles.

299

300

TABLE 5.4

CHAPTER 5  Neck Neck Muscles Origin

Insertion

Action

• Base of mandible and skin of lower face

• Changes facial expression

• Mastoid process, lateral half of superior nuchal line

• Flexes head and neck

• Thyroid cartilage • Superior border of manubrium and medial clavicle • Manubrium and medial end first costal cartilage • Superior border of scapula

• Inferolateral border hyoid bone • Hyoid bone

• Lower hyoid bone, raise larynx • Lower hyoid bone

• Thyroid cartilage

• Lower larynx

• Inferolateral border hyoid bone

• Lower hyoid bone and larynx

• Posterior belly—mastoid notch of temporal bone; anterior belly—lower border of mandible • Body of mandible

• Ends as intermediate tendon between the two bellies that attach to the hyoid bone • Mandibular symphysis and hyoid bone • Superior surface of hyoid bone

• Jaw opener (speech muscle)

Front of Neck—Anterior Triangle • Fascia and skin over pectoralis Platysma major and deltoid muscles Sternocleidomastoid (SCM) Sternal head • Upper manubrium Clavicular head Infrahyoid Muscles Thyrohyoid Sternohyoid Sternothyroid Omohyoid Suprahyoid Muscles Digastric Mylohyoid Stylohyoid Geniohyoid Prevertebral Muscles Longus capitis Longus colli

• Sternal end of clavicle

• Styloid process of temporal bone • Mandibular symphysis • Anterior tubercles of transverse processes of C3–C6 • Bodies of C4–T3; anterior tubercles of transverse processes of C3–C6

Back of Neck—Posterior Triangle Scalene Muscles Anterior • Anterior tubercles of transverse processes of C3–C6 Middle • Posterior tubercles of transverse processes of C2–C7 Posterior • Posterior tubercles of transverse processes of C4–C6 Trapezius • Occipital bone and spinous processes C7–T12 Levator scapulae • Transverse processes of upper four cervical vertebrae Splenius capitis • Lower cervical and upper thoracic vertebrae Splenius cervicis • Spinous processes of T1–T6 and ligamentum nuchae

Muscles Within the Posterior Triangle The muscles of the posterior triangle include the trapezius, splenius capitis, levator scapulae, and anterior, middle, and posterior scalene muscles. The trapezius muscle, a superficial muscle located on the posterior portion of the neck, elevates the scapula. It originates from the occipital bone and spinous processes of C7–T12 to insert on the clavicle, acromion, and spine of the scapula (Figs. 5.79 and 5.80). Located just anterior to the trapezius muscle, the splenius capitis muscle arises from the lower cervical

• Elevate floor of mouth

• Body of hyoid bone

• Move hyoid bone posterior and superior • Jaw opener

• Basilar part of occipital bone

• Flex head

• Anterior arch of C1; anterior tubercles of transverse processes of C5–C6, anterior bodies of C2–C4

• Flex neck, rotate and bend neck laterally

• Scalene tubercle of first rib

• Elevates first rib, flexes cervical vertebrae • Elevates first rib, flexes cervical vertebrae • Laterally flexes head; rotates head and neck • Elevates the scapula

• First rib • Second rib • Clavicle; acromion; scapular spine • Vertebral border of the scapula

• Raises the scapula

• Occipital bone

• Extends head

• Posterior tubercles of transverse processes of C1–C4

• Extends head

and upper thoracic vertebrae to insert on the occipital bone and acts to extend the head (Figs. 4.54, 5.54, and 5.55). The levator scapulae muscle is located in the posterolateral portion of the neck. It arises from the transverse processes of the upper four cervical vertebrae to insert on the vertebral border of the scapula and acts to raise the scapula (Figs. 5.77–5.79). The scalene muscle group (anterior, middle, and posterior scalene muscles) is located in the anterolateral portion of the neck. The muscles originate from the transverse processes of the cervical vertebrae to insert on the first two ribs.

CHAPTER 5  Neck Together, the scalene muscles act to elevate the upper two ribs and flex the neck. The anterior and middle scalene muscles can serve as landmarks for the brachial plexus as it courses between them (Figs. 5.77 and 5.78).

(These muscles are identified on Figs. 5.52–5.69 and listed in Table 5.4.) Two other prominent muscle groups found in the neck are the erector spinae and transversospinal, which are discussed in Chapter 4. Transverse process of C1 DEEP

SUPERFICIAL Trapezius muscle

Levator scapulae muscle Rhomboid muscle

Deltoid muscle

Scapula

Teres minor muscle Triceps brachii muscle

Teres major muscle

Serratus anterior muscle

Infraspinatus muscle

FIG. 5.79  Posterior view of trapezius and levator scapulae muscles.

Temporalis muscle

Orbicularis oculi muscle

Masseter muscle Zygomaticus muscle

301

Buccinator muscle Sternocleidomastoid muscle

Orbicularis oris muscle

Platysma muscle

FIG. 5.80  Lateral view of superficial neck muscles.

Trapezius muscle

302

CHAPTER 5  Neck

VASCULAR STRUCTURES The extracranial vessels of the neck include the carotid and vertebral arteries and the jugular veins (Tables 5.5 and 5.6). These vessels are located primarily in the lateral portions of the neck (Figs. 5.81–5.86). The vascular structures can be identified in the sequential images in Figs. 5.56–5.69.

Carotid Arteries The right common carotid artery arises from the brachiocephalic trunk posterior to the sternoclavicular joint. The left common carotid artery arises directly from the aortic arch (Fig. 5.81). The common carotid arteries lie medial to the internal jugular vein and bifurcate into the internal and external carotid arteries at approximately the level of the third and fourth cervical vertebrae (C3–C4). Located on the external surface at the bifurcation of the common carotid artery is the carotid body, a small neurovascular structure that acts as a chemoreceptor to sense changes in the chemical composition of blood to regulate oxygen and pH levels (Fig. 5.82). The internal carotid artery ascends the neck, vertically, to enter the base of the skull through the carotid canal of the temporal bone. At its origin, there is a dilatation called the carotid sinus, which contains baroreceptors that react to changes in arterial blood pressure (Fig. 5.82). The internal carotid artery has no branches in the neck but has branches in the head to supply blood to the orbit and brain. As the external carotid artery ascends the neck, it passes through the parotid gland to the level of

TABLE 5.5

Carotid body tumors are the most common paraganglioma of the head and neck. These tumors develop within the adventitia of the medial aspect of the carotid bifurcation. The most common presentation is as an asymptomatic palpable neck mass in the anterior triangle of the neck. As the tumor enlarges and compresses the carotid artery and the surrounding nerves, other symptoms may also be present, such as pain, tongue paresis, hoarseness, Horner syndrome, and dysphagia. These tumors are treated with either surgery or radiotherapy.

Vertebral Arteries The vertebral arteries begin as a branch of the subclavian artery and ascend the neck through the transverse foramina of C6–C1. They then enter the foramen magnum and join to form the basilar artery. The vertebral and basilar arteries supply blood to the posterior aspect of the brain (Figs. 5.56–5.69 and 5.82–5.85).

Arteries of the Neck

Arteries of the Neck

Origin

Common Carotid Artery Left Common Carotid Right Common Carotid Internal Carotid Artery External Carotid Artery

Aortic arch Right brachiocephalic artery Common carotid artery Common carotid artery

Vertebral Arteries

Subclavian artery

TABLE 5.6

the temporomandibular joint, where it divides into its terminal branches to supply blood to the face and neck. These branches include the superior thyroid, lingual, facial, occipital, posterior auricular, and ascending pharyngeal arteries (Figs. 5.81–5.85 and Table 5.5). The external carotid artery changes position in relation to the internal carotid artery as it ascends the neck. At its lower level, the external carotid artery is anterior and medial to the internal carotid artery and then becomes anterior and lateral to the internal carotid artery at its higher level (Figs. 5.56–5.69).

Branches Internal and external carotid arteries Ophthalmic, anterior and middle cerebral arteries Superior thyroid, lingual, facial, occipital, posterior auricular, and ascending pharyngeal arteries Posterior inferior cerebellar artery

Veins of the Neck

Veins of the Neck

Termination

Tributaries

Internal jugular vein

Subclavian vein

External jugular vein

Subclavian vein

Vertebral veins

Brachiocephalic vein

Inferior petrosal sinus, facial, lingual, pharyngeal, superior and middle thyroid, and occasionally the occipital veins Retromandibular, anterior jugular, temporal, and maxillary veins, and occasionally the occipital vein Internal and external vertebral venous plexuses and deep cervical veins

CHAPTER 5  Neck Internal carotid artery

External carotid artery

Internal carotid artery

Superior thyroid vein Superior thyroid vein Superior thyroid artery

Thyroid gland

Superior thyroid artery Internal jugular vein

Parathyroid gland

Middle thyroid vein

Internal jugular vein

Common carotid artery

Middle thyroid vein

Inferior thyroid artery

Inferior thyroid artery

Vertebral artery Thyrocervical trunk

Common carotid artery

Subclavian artery

Thyrocervical trunk Subclavian artery

Trachea Subclavian vein

Subclavian vein

Left brachiocephalic vein

Inferior thyroid vein

Aortic arch

Right brachiocephalic vein Brachiocephalic trunk Inferior thyroid vein Superior vena cava

FIG. 5.81  Anterior view of extracranial vasculature.

303

304

CHAPTER 5  Neck Carotid sinus nerve (branch of CN IX)

Carotid sinus

Carotid body

Right vertebral artery Right internal carotid artery Right external carotid artery Right facial artery Left lingual artery Hyoid bone

C1 (atlas) Left ascending pharyngeal artery Left vertebral artery Left external carotid artery Left internal carotid artery Carotid sinus Left superior thyroid artery

Superior laryngeal artery Left common carotid artery Ascending cervical artery Right inferior thyroid artery Costocervical trunk Right vertebral artery Thyrocervical trunk Right common carotid artery

Clavicle

Right subclavian artery Brachiocephalic trunk Left subclavian artery

Sternoclavicular joint Right internal thoracic artery

Aortic arch

FIG. 5.82  Anterior oblique view of extracranial arteries.

CHAPTER 5  Neck S

Left internal carotid artery Left lingual artery

Left external carotid artery

Carotid bifurcation Left facial artery A

P Left vertebral artery

Right common carotid artery

Left common carotid artery Left subclavian artery

Brachiocephalic trunk

Aortic arch

I

FIG. 5.83  Anterior oblique 3D CTA of extracranial arteries.

305

306

CHAPTER 5  Neck

S

Anterior cerebral artery Middle cerebral artery

Basilar artery

External carotid artery

External carotid artery Internal carotid artery

Internal carotid artery

R

L

Carotid sinus

Carotid sinus Common carotid artery

Vertebral artery

Vertebral artery

Common carotid artery

Subclavian artery Subclavian artery

Aortic arch

Brachiocephalic trunk

I

FIG. 5.84  MRA of extracranial arteries.

CHAPTER 5  Neck S Anterior cerebral arteries Middle cerebral artery Carotid siphon

Basilar artery

Internal carotid artery

Vertebral artery

External carotid artery

Carotid bifurcation R

L Carotid sinus

Common carotid artery

Common carotid artery

Subclavian artery

Subclavian artery Brachiocephalic trunk

Aortic arch

I

FIG. 5.85  3D CTA of intracranial and extracranial arteries.

307

308

CHAPTER 5  Neck

Jugular and Vertebral Veins The internal jugular veins drain blood from the brain and superficial parts of the face and neck and are typically the largest of the vascular structures of the neck (Table 5.6). The internal jugular veins commence at the jugular foramen in the posterior cranial fossa and descend the lateral portion of the neck to unite with the subclavian vein to form the brachiocephalic vein (Figs. 5.81 and 5.86). The internal jugular veins typically run lateral to the common carotid artery and posterior to the internal carotid artery at the upper levels of the neck (Figs. 5.56–5.69). Tributaries of the internal jugular vein include the inferior petrosal sinus, facial, lingual, pharyngeal, superior, and middle thyroid veins, and often the occipital vein. One of these tributaries, the facial vein, is commonly identified as it drains the anterior and lateral regions of the face (Fig. 5.86). The external jugular veins begin near the angle of the mandible and cross the SCM just beneath the skin to empty into the subclavian vein. Tributaries of the external jugular veins include the retromandibular and anterior jugular veins and occasionally the occipital veins. Blood from the lateral region of the face is drained by the retromandibular vein that courses inferiorly through the parotid gland. The anterior jugular vein begins at approximately the level of the hyoid bone and drains blood from the lower lip. This vessel passes beneath the SCM to open into the termination of the external jugular vein. Jugular veins are identified in Figs. 5.56–5.69.

The vertebral veins course within the transverse foramina of the cervical vertebrae along with the vertebral arteries to drain the cervical spinal cord and the posterior surface of the skull (Figs. 5.53, 5.54, 5.61, and 5.69; see also Chapter 4, Fig. 4.132). The vertebral veins drain into the posterior aspect of the brachiocephalic vein. The vascular structures can be identified on the sequential images in Figs. 5.52–5.69.

REFERENCES Applegate, E. (2010). The anatomy and physiology learning system (4th ed.). St. Louis: Saunders. Fehrenback, M. J., & Herring, S. W. (2017). Illustrated anatomy of the head and neck (5th ed.). St. Louis: Elsevier. Frank, G. (2012). Merrill’s atlas of radiographic positions and radiologic procedures (12th ed.). St. Louis: Mosby. Haaga, J. R., & Boll, D. T. (2017). CT and MRI of the whole body (6th ed.). Philadelphia: Elsevier. Larsen, W. J. (2002). Anatomy: Development, function, clinical correlations. Philadelphia: Saunders. Mosby. (2012). Mosby’s medical, nursing, and allied health dictionary (8th ed.). St. Louis: Mosby. Ryan, S., & McNicholas, M. (2010). Anatomy for diagnostic imaging (3rd ed.). Philadelphia: Saunders. Seidel, H. M., Ball, J. W., & Dains, J. E., et al. (2010). Mosby’s guide to physical examination (7th ed.). St. Louis: Mosby. Som, P. M., & Curtin, H. D. (2011). Head and neck imaging (5th ed.). St. Louis: Mosby. Standring, S. (2012). Gray’s anatomy: The anatomical basis of clinical practice (41st ed.). New York: Elsevier.

Superficial temporal veins

Pterygoid venous plexus

Occipital vein

Retromandibular vein Facial vein Superior thyroid vein

Deep cervical vein Internal jugular vein

Submental vein Hyoid bone Anterior jugular vein Middle thyroid vein

External jugular vein

Brachiocephalic vein

Subclavian vein

FIG. 5.86  Lateral view of extracranial veins.

CHAPTER

6

S

Thorax R

Anyone who would attempt to operate on the heart should lose the respect of his colleagues.

L

Christian Albert Theodor Billroth, 1881

Many structures of the thorax are in constant motion. Although physiologic motion can make imaging difficult, a thorough knowledge of thoracic anatomy and physiology can improve diagnostic imaging of this area (Fig. 6.1). This chapter demonstrates the sectional anatomy of the structures listed in the outline.

I

FIG. 6.1  Coronal CT reformat of thorax with numerous pulmonary emboli.

OBJECTIVES • • • • • •

Describe the structures that constitute the bony thorax. Define the thoracic inlet and outlet. Understand the function and layers of the pleura. Identify and describe the structures of the lungs. Identify the mainstem bronchi and their divisions. List the structures of the mediastinum, and describe their anatomic relationships to each other. • Identify the structures of the heart, and explain the circulation of blood through the heart.

• Identify the great vessels, and describe the distribution of their associated arteries and veins. • Differentiate between pulmonary arteries and veins by function and location. • Identify the coronary arteries and veins. • List the muscles involved in respiration by function and location. • List and describe the layers of the breast.

OUTLINE BONY THORAX, 310 Thoracic Apertures, 310 PLEURAL CAVITIES, 314 LUNGS, 315 BRONCHI, 320 MEDIASTINUM, 324 Thymus Gland, 325 Trachea and Esophagus, 327 LYMPHATIC SYSTEM, 328 Lymph Nodes, 328 Lymph Vessels, 331 HEART AND VASCULATURE, 333 Superficial Landmarks, 333

Pericardium, 335 Heart Wall, 338 Chambers, 338 Cardiac Conduction System, 339 Cardiac Valves, 348 GREAT VESSELS, 351 Circulation of Blood Through the Heart, 365 Branches of the Aortic Arch, 365 Tributaries of the Superior Vena Cava, 368

Copyright © 2019, Elsevier Inc.

CORONARY CIRCULATION, 370 Coronary Arteries, 370 Cardiac Veins, 375 OFF-AXIS CARDIAC IMAGING, 380 AZYGOS VENOUS SYSTEM, 388 MUSCLES, 391 Muscles associated with Respiration, 391 Muscles of the Anterior and Lateral Thoracic Walls, 396 BREAST, 397

309

CHAPTER 6   Thorax

310

Superior thoracic aperture (thoracic inlet) Jugular notch T1 1

Manubrium

2

Sternal angle

3 Body

4

Ribs

5 Xiphoid process

6

Costal cartilages

7

T11

8

T12

9 10 11 12

Inferior thoracic aperture (thoracic outlet)

the third through seventh ribs (Figs. 6.2, 6.6, and 6.7). The small xiphoid process is located on the inferior border of the sternum and is a site for muscle attachments including the rectus abdominis and transversus abdominis muscles (Figs. 6.4 and 6.8). Forming the lateral borders of the thoracic cage are the 12 pairs of ribs. The spaces between adjacent ribs are referred to as the intercostal spaces. All 12 pairs of ribs articulate posteriorly with the thoracic spine. The ribs consist of a head, neck, tubercle, and body (Figs. 6.7 and 6.8). The facets of the head of the rib articulate with the vertebral bodies at the costovertebral joints, whereas the facets of the tubercles articulate with the transverse processes of the vertebrae to form the costotransverse joints (Fig. 6.7). The first seven pairs of ribs (true ribs) articulate anteriorly with the sternum via costal cartilage. The lower five pairs of ribs are considered false ribs because they do not attach directly to the sternum. The costal cartilage of the 8th, 9th, and 10th ribs attach to the costal cartilage of the 7th rib. The 11th and 12th ribs are considered floating because they attach only to the thoracic vertebrae and contain no neck or tubercle, only vertebral and sternal ends (Fig. 6.2).

FIG. 6.2  Anterior view of thoracic cage.

Thoracic Apertures BONY THORAX The bony thorax protects the organs of the thorax and aids in respiration. It consists of the thoracic vertebrae, sternum, ribs, and costal cartilages (Fig. 6.2). The 12 thoracic vertebrae make up the posterior boundary of the thoracic cage. The anterior boundary is created by the sternum, located midline. The sternum has three components: manubrium, body, and xiphoid process (Figs. 6.3 and 6.4). The triangular-shaped manubrium is the most superior portion and articulates with the first two pairs of ribs and the clavicles. It articulates with the clavicles at the clavicular notch to form the sternoclavicular (SC) joints (Fig. 6.5). A common landmark, the jugular notch, is located on the superior border of the manubrium at approximately the level of T2–T3. The manubrium and body of the sternum come together at an angle to form a ridge known as the sternal angle, which is located at approximately the level of T4–T5. The slender body of the sternum has several indentations along its sides where it articulates with the cartilage of

There are two openings, or apertures, associated with the bony thorax. The superior thoracic aperture (thoracic inlet) is formed by the first thoracic vertebra, the first pair of ribs and their costal cartilages, and the manubrium. This aperture allows for the passage of nerves, vessels, and viscera from the neck into the thoracic cavity. The inferior thoracic aperture (thoracic outlet) is much larger and is made up of the 12th thoracic vertebra, 12th pair of ribs and costal margins, and xiphoid sternal junction (Figs. 6.2, 6.5, and 6.8).

Thoracic Outlet Syndrome Thoracic outlet syndrome (TOS) refers to a group of disorders causing pain and paresthesias in the neck, shoulder, arms, or hands resulting from compression of the brachial plexus and/or subclavian vessels as they pass through the thoracic outlet. The name is somewhat controversial because the location of the pathology is technically the thoracic inlet.

CHAPTER 6   Thorax

311

S

Manubrium

Ascending aorta

Left mainstem bronchus

Sternal angle

Right pulmonary artery A

P

Body of sternum

Left atrium

Right atrium Xiphoid process

IVC (inferior vena cava)

I

FIG. 6.3  Sagittal, T1-weighted MRI of thoracic cage. S

Manubrium Pulmonary trunk Left mainstem bronchus

Sternal angle

Descending aorta

Body of sternum

Thoracic vertebra A

P Left atrium

Right ventricle

Left ventricle

Xiphoid process

I

FIG. 6.4  Sagittal CT reformat of sternum.

312 Subclavius muscle

CHAPTER 6   Thorax

Sternoclavicular joint

Rib

Manubrium

A

P

Clavicle

T1

FIG. 6.5  Axial CT of superior thoracic aperture.

Right atrium

Bicuspid valve

Costal cartilage

A

Body of sternum

Right ventricle

Interatrial septum

Right inferior pulmonary vein Left ventricle R

L Aortic semilunar valve Left inferior pulmonary vein Descending aorta Head of rib

Angle of rib

Costovertebral Costotransverse Left atrium joint joint

FIG. 6.6  Axial CT of sternum.

P

Thoracic vertebra

Neck of rib

CHAPTER 6   Thorax Sternum

A

313

Costal cartilage Sternum end

R

L Vertebral body

Costovertebral joint

Body

Head

Tubercle

Neck

Angle Costotransverse joints

P

Transverse process

Vertebral end

FIG. 6.7  Axial view of ribs with costovertebral and costotransverse joints.

Tubercle of rib

Costovertebral joint

Xiphoid process

A

Sternal end of rib

Head of rib

Neck of rib

Body of rib

R

L

Vertebral end of rib

Costotransverse joint

T12

FIG. 6.8  Axial CT at inferior thoracic aperture.

P

Transverse process

Vertebral body

Angle of rib

314

CHAPTER 6   Thorax provides lubrication between the surfaces during breathing (Figs. 6.9 and 6.10). Deep pockets or recesses of the pleural cavities are the costomediastinal and costodiaphragmatic recesses. The costomediastinal recesses are located at the point where the mediastinum and costal cartilages meet anteriorly, and the costodiaphragmatic recesses are located where the diaphragm and ribs connect inferiorly. These recesses serve as expansions to provide additional pleural space where parts of the lung can glide during inspiration (Figs. 6.9 and 6.10).

PLEURAL CAVITIES Each lung lies within a single pleural cavity that is lined by a serous membrane, or pleura. The pleura can be divided into two layers. The parietal pleura, the outer layer, is continuous with the thoracic wall and diaphragm and moves with these structures during respiration. The visceral pleura is the inner layer that closely covers the outer surface of the lung and continues into the fissures to cover the individual lobes as well. Both membranes secrete a small amount of pleural fluid that

Pericardial cavity

Costomediastinal recess

Heart

A

Right pleural cavity

Left pleural cavity

R

L

Right lung

Left lung

Costodiaphragmatic recess

Parietal pleura

Visceral pleura

P

Mediastinum

FIG. 6.9  Axial cross-section of lungs with pleura.

Trachea A

Aortic arch

Left lung

Visceral pleura

R

L

Right lung

Esophagus

P

FIG. 6.10  Axial CT of lungs with pleural effusion.

Pleural effusion

Parietal pleura

CHAPTER 6   Thorax

has just superior (upper) and inferior (lower) lobes (Figs. 6.11–6.15). The inferior lobe of the right lung is separated from the middle and superior lobes by the oblique (major) fissure, termed oblique because of its posterosuperior to anteroinferior course (Figs. 6.11 and 6.13). Separating the middle lobe from the superior lobe is the horizontal (minor) fissure (Figs. 6.11–6.13 and 6.15A). An oblique fissure also separates the superior and inferior lobes of the left lung (Figs. 6.11 and 6.12). The left lung has a large notch on the medial surface of its superior lobe called the cardiac notch and a tonguelike projection off its inferoanterior surface termed the lingula (Figs. 6.11 and 6.15B). Each lung has an opening on the medial surface termed the hilum. This opening acts as a passage for the mainstem bronchi, blood vessels, lymph vessels, and nerves to enter or leave the lung and is commonly referred to as the root of the lung (Figs. 6.15–6.17).

LUNGS The lungs are the organs of respiration. They are composed of a spongelike material, the parenchyma, and are surrounded by the visceral pleura. The large conicalshaped lungs extend up to or slightly above the level of the first rib at their apex and down to the dome of the diaphragm at their wide concave-shaped bases or diaphragmatic surfaces (Figs. 6.11–6.13). Each lung has a mediastinal or medial surface that is apposed to the mediastinum and a costal surface that is apposed to the inner surface of the rib cage. Each lung also has inferior, anterior, and posterior borders. The inferior border extends into the costodiaphragmatic recess of the pleural cavity, and the anterior border of each lung extends into the costomediastinal recess of the pleural cavity (Fig. 6.13). Two prominent angles can be identified at the medial and lateral edges of the lung bases. The medial angle is termed the cardiophrenic sulcus, and the lateral angle is termed the costophrenic sulcus (Figs. 6.11 and 6.12). The lungs are divided into lobes by fissures that are lined by pleura. The right lung has three lobes (superior [upper], middle, and inferior [lower]), whereas the left lung

Cystic disease of the lung encompasses a wide variety of pathologic processes that are characterized by “holes” or abnormal air-containing spaces within the lung parenchyma.

6

7UDFKHD

$SH[RI ULJKWOXQJ

6XSHULRUOREH RIOHIWOXQJ

6XSHULRUOREH RIULJKWOXQJ

+LOXP

&DULQD 5LJKWPDLQVWHP EURQFKXV

/HIWPDLQVWHP EURQFKXV

5LJKWVXSHULRU OREHEURQFKXV

&RVWDOVXUIDFH

5LJKWKRUL]RQWDOILVVXUH 5LJKWREOLTXH ILVVXUH

/

5

/HIWREOLTXH ILVVXUH /HIWVXSHULRU OREHEURQFKXV /HIWLQIHULRU OREHEURQFKXV

5LJKWPLGGOH DQGORZHU OREHEURQFKL

0HGLDVWLQDO VXUIDFH

,QIHULRUOREHRI ULJKWOXQJ %DVHRI ULJKWOXQJRU GLDSKUDJPDWLFVXUIDFH

315

,QIHULRUOREH RIOHIWOXQJ

0LGGOHOREH RIULJKWOXQJ ,

&DUGLRSKUHQLFVXOFXV PHGLDODQJOH

,QIHULRUERUGHU

/LQJXOD &DUGLDF QRWFK

FIG. 6.11  Anterior view of bronchial tree.

&RVWRSKUHQLFVXOFXV ODWHUDODQJOH

316

CHAPTER 6   Thorax Thoracic spine

S

Thoracic aorta Left lung

Right superior lobe Left superior lobe

Right oblique fissure

Left oblique fissure R

L

Right inferior lobe

Left inferior lobe Costophrenic sulcus

I

Cardiophrenic sulcus

FIG. 6.12  Coronal CT reformat of lungs. Superior lobe

S

Apex

Right lung

Right oblique fissure

A

P Posterior border

Middle lobe

Inferior lobe

Anterior border

Inferior border diaphragmatic surface

I

FIG. 6.13  Sagittal CT reformat of right lung.

CHAPTER 6   Thorax

Superior vena cava

Right superior lobe

Ascending aorta

Left superior lobe

A

Right superior lobe bronchus

Pulmonary trunk

Left mainstem bronchus

Right pulmonary artery R

L

Right oblique fissure

Left superior lobe bronchus

Right mainstem bronchus

Left pulmonary artery

Right inferior lobe

Descending aorta

P

Left inferior lobe

FIG. 6.14  Axial CT of lungs with fissures.

Left oblique fissure

317

CHAPTER 6   Thorax

318

Apex

Groove for right subclavian artery

Superior lobe Groove for superior vena cava

Oblique fissure Superior lobar bronchus

Groove for azygos vein

Right pulmonary artery

Anterior border

Right mainstem bronchus Right superior pulmonary vein

Hilum of lung A

P

Horizontal fissure

Groove for esophagus

Cardiac impression

Lower right pulmonary vein

Middle lobe Oblique fissure

Pulmonary ligament

Base of lung Groove for inferior vena cava

A

Inferior lobe Groove for left subclavian artery

Apex

Groove for left brachiocephalic vein

Superior lobe

Left pulmonary artery Groove for aorta

Left mainstem bronchus Left pulmonary veins

Hilum of lung P

A

Posterior border Cardiac impression Cardiac notch Pulmonary ligament Inferior lobe

Oblique fissure Lingula

Inferior border

B

FIG. 6.15  Medial view of lungs. (A) Right lung. (B) Left lung.

CHAPTER 6   Thorax Ascending aorta

319

A

Left lung

Right lung

Pulmonary trunk Hilum L

R

Descending aorta

Right pulmonary artery Esophagus Azygos vein P

FIG. 6.16  Axial, T1-weighted MRI of lungs at hilum.

6XSHULRU YHQDFDYD

5LJKW SXOPRQDU\ DUWHU\

$

$VFHQGLQJ DRUWD

5

/

+LOXP

5LJKW PDLQVWHP EURQFKL

FIG. 6.17  Axial CT of lungs at hilum.

3

/HIW PDLQVWHP EURQFKL

'HVFHQGLQJDRUWD

320

CHAPTER 6   Thorax

BRONCHI The trachea bifurcates into the left and right mainstem (primary) bronchi at approximately the level of T5. This location is commonly referred to as the carina (Fig. 6.11). The right mainstem bronchus is wider, shorter, and more vertical in orientation than the left. At the hilum, the mainstem bronchi enter the lungs and divide into secondary or lobar bronchi. Secondary bronchi correspond to the lobes of the lungs, with three divisions on the right (superior, middle, inferior) and two divisions on the left (superior and inferior) (Figs. 6.11 and 6.18– 6.20). There is further division of the secondary bronchi into tertiary or segmental bronchi, which extend into each segment of the lobes (bronchopulmonary segments) (Figs. 6.21 and 6.22 and Table 6.1). There are typically 10 segments within each lung. Each bronchopulmonary segment is functionally independent and can be individually removed surgically. The bronchial tree continues to divide many times into smaller bronchi, then into bronchioles. Each bronchiole continues to divide, approximately 23 times, until it reaches the terminal end as alveoli, which are the functional units of the respiratory system. Gaseous exchange between alveolar air and capillary blood occurs through the walls of the alveoli (Fig. 6.23).

$QWHULRU VHJPHQWDOEURQFKXV

The basic unit of pulmonary structure and function is called the secondary pulmonary lobule. It is the smallest component of lung tissue that is surrounded by connective tissue, and it measures approximately 1 to 2 cm. It consists of three to five acini that contain alveoli for gas exchange with a terminal bronchiole and artery located in the center of the lobule. At the periphery of the lobule is the interstitial septa formed by connective tissue, pulmonary veins, and lymphatics (Figs. 6.23 and 6.24). High-resolution computed tomography (CT) is capable of demonstrating the secondary pulmonary lobule and can help characterize interstitial lung disease based on the type of pathology present within the lobule.

Lung cancer remains the leading cause of cancerrelated deaths in both men and women in the United States. Approximately 1 out of 4 cancer deaths is from lung cancer. According to the American Cancer Society more people die of lung cancer than of colon, breast, and prostate cancers combined. Lung cancer typically occurs in older individuals, with an average age at the time of diagnosis of 70 years. Overall, the chance that a man will develop lung cancer in his lifetime is about 1 in 14 while it is about 1 in 17 for women.

6XSHULRU YHQDFDYD

5LJKW PDLQVWHP EURQFKXV

$

6WHUQXP

$VFHQGLQJ DRUWD

&DULQD /HIWVXSHULRU OREH /HIWPDLQVWHP EURQFKXV

5LJKWVXSHULRU OREHEURQFKXV

/HIWSXOPRQDU\ DUWHU\ 5

/

5LJKW VXSHULRU OREH

$SLFDOVHJPHQWDO EURQFKXV 3RVWHULRUVHJPHQWDO EURQFKXV

3RVWHULRU VHJPHQWDO EURQFKXV

5LJKWREOLTXH 5LJKW (VRSKDJXV ILVVXUH LQIHULRU OREH

3

'HVFHQGLQJ /HIW DRUWD LQIHULRU OREH

FIG. 6.18  Axial CT of mainstem bronchi.

/HIWREOLTXH ILVVXUH

CHAPTER 6   Thorax Anterior Right superior segmental bronchus lobe bronchus

A

321

Right mainstem bronchus

R

L

Posterior segmental bronchus

Carina

Esophagus

P

Left mainstem bronchus

Left superior lobe bronchus

FIG. 6.19  Axial CT of left superior lobe bronchus.

Right middle lobe bronchus

Right superior Superior Ascending lobe vena cava aorta A Left superior lobe bronchus

Right inferior lobe bronchus

R

L

Left inferior lobe bronchus Anterior basal segmental bronchus

Anterior basal segmental bronchus

Right inferior lobe

Medial basal segmental bronchus of inferior lobe

P

FIG. 6.20  Axial CT of right inferior lobe bronchus.

322

CHAPTER 6   Thorax Superior lobe Superior lobe 1

1 2

2

Viewed laterally

3

3

6 6

Lingula

4 5

Inferior lobe

8

9

10

Middle lobe

12 1

1 2

1

2 6

3

8

9 10

2 3 11 12 6

3 Upper lobe

11

4

6

5 8

7

10 9

8 7

1

2

Inferior lobe

Upper lobe

3 6

9 10

Viewed medially

11 7

5 8

Middle lobe

10

9

10 Inferior lobe

Inferior lobe

7 9

12

Lingula

8

FIG. 6.21  Trachea and bronchopulmonary segments. Bronchopulmonary segments: 1, apical; 2, posterior; 3, anterior; 4, lateral; 5, medial; 6, superior; 7, medial basal; 8, anterior basal; 9, lateral basal; 10, posterior basal; 11, superior lingular; 12, inferior lingular. S $QWHULRU 6XSHULRU 3RVWHULRU $SLFDO VHJPHQWDO VHJPHQWDO VHJPHQWDO OREDU EURQFKXV EURQFKXV EURQFKXV EURQFKXV

&DULQD

$SLFDO VHJPHQWDO EURQFKXV

0HGLDO VHJPHQWDO EURQFKXV

3RVWHULRU VHJPHQWDOEURQFKXV /HIWPDLQVWHP EURQFKXV

%URQFKXV LQWHUPHGLXV

R

$QWHULRUVHJPHQWDO EURQFKXV

/DWHUDO VHJPHQWDO EURQFKXV

/HIWVXSHULRU OREHEURQFKXV

,QIHULRUOREH EURQFKXV

L

6XSHULRUOLQJXODU VHJPHQWDOEURQFKXV

0HGLDO VHJPHQWDO EURQFKXV

,QIHULRUOLQJXODU VHJPHQWDOEURQFKXV

$QWHULRUEDVDO VHJPHQWDO EURQFKXV

/HIWLQIHULRU OREH EURQFKXV 0HGLDOEDVDO VHJPHQWDO EURQFKXV

0HGLDO EDVDO VHJPHQWDO EURQFKXV

3RVWHULRU VHJPHQWDO EURQFKXV I

/DWHUDO EDVDO VHJPHQWDO EURQFKXV

$QWHULRU EDVDO VHJPHQWDO EURQFKXV

FIG. 6.22  Coronal CT, 3D volume-rendered image of central and peripheral airways.

CHAPTER 6   Thorax TABLE 6.1

Bronchopulmonary Segments

Lobe

Right Lung

Left Lung

Superior lobe

Apical segment (1) Posterior segment (2) Anterior segment (3)

Middle lobe

Lateral segment (4) Medial segment (5) Superior segment (6) Medial basal segment (7) Anterior basal segment (8) Lateral basal segment (9) Posterior basal segment (10)

Apical segment (1) Posterior segment (2) Anterior segment (3) Superior lingular segment (11) Inferior lingular segment (12)

Inferior lobe

323

Superior segment (6) Medial basal segment (7) Anterior basal segment (8) Lateral basal segment (9) Posterior basal segment (10) Terminal bronchiole Pulmonary artery

Pulmonary vein

Interstitial septa

Acinus

Alveoli

FIG. 6.23  Axial view of secondary pulmonary lobule. A

R

L

Segmental bronchus

Segmental pulmonary veins

Descending aorta

Pulmonary vein

FIG. 6.24  Axial CT of secondary pulmonary lobule.

P

Pulmonary artery

CHAPTER 6   Thorax

324

MEDIASTINUM The mediastinum is the midline region of the thoracic cavity located between the two pleural cavities of the lungs. It extends from the superior thoracic aperture to the diaphragm and is bordered anteriorly by the sternum and posteriorly by thoracic vertebrae. The mediastinum can be subdivided into compartments for descriptive purposes. The superior and inferior compartments are made by drawing an imaginary line between the sternal angle and the intervertebral disk of T4–T5. The superior compartment constitutes the upper portion of the mediastinum. It contains the thymus gland and acts as a

conduit for structures as they enter and leave the thoracic cavity. The inferior compartment can be further divided into anterior, middle, and posterior compartments (Fig. 6.25). The anterior compartment is located anterior to the pericardial sac and posterior to the sternum. The middle compartment is the area that contains the pericardial sac, heart, and roots of the great vessels. The posterior compartment is the area lying posterior to the pericardium and anterior to the inferior eight thoracic vertebrae. Structures located within the mediastinum include the thymus gland, trachea, esophagus, lymph nodes, thoracic duct, heart and great vessels, and various nerves (Table 6.2).

SUPERIOR MEDIASTINUM

Left common carotid artery

S

Trachea

C7

Line of first rib

Left subclavian artery

T1

Thymus

T2

Aortic arch

T3

Manubrium

Pulmonary artery (right)

T4

Sternal angle

T5

ANTERIOR MEDIASTINUM A

T7

MIDDLE MEDIASTINUM Inferior mediastinum

Mainstem bronchus (left)

T6

T8 T9

Anterior pericardium

T10

Diaphragm

T11

P Heart Posterior pericardium

Esophagus

IVC

T12

Aorta

POSTERIOR MEDIASTINUM

L1

I

FIG. 6.25  Sagittal view of mediastinal compartments. IVC, Inferior vena cava.

TABLE 6.2

Mediastinal Compartments

Compartment

Location

Structures

Superior

Thymus, aortic arch, superior vena cava (SVC), vagus and phrenic nerves, lymph nodes, superior trachea, esophagus, thoracic duct

Anterior

Between the manubrium and T1–T4. Bounded superiorly by the thoracic inlet and inferiorly by a plane between the sternal angle and the T4–T5 disk space Divided into three compartments below the superior mediastinum: anterior, middle, and posterior Between sternal body and pericardium

Middle

Bounded by the fibrous pericardium

Posterior

Between fibrous pericardium and lower 4th–12th thoracic vertebral bodies

Inferior

Inferior thymus, fat, lymph nodes, mediastinal branches of internal thoracic artery Pericardium, heart, ascending aorta, lower half of SVC, tracheal bifurcation and main bronchi, central pulmonary and systemic vessels, lymph nodes Inferior esophagus, descending thoracic aorta, azygos and hemiazygos veins, thoracic duct, lymph nodes

CHAPTER 6   Thorax

Thymus Gland The thymus gland is a triangular-shaped bilobed gland of lymph tissue located in the superior portion of the mediastinum just behind the manubrium (Figs. 6.26– 6.28). It is considered the primary lymphatic organ responsible for the development of cellular immunity. T lymphocytes within the blood reach the thymus as stem cells, where they are stored while they undergo T-cell differentiation and maturation. The thymus gland

produces a hormone, thymosin, that is responsible for the development and maturation of lymphocytes. The thymus gland reaches its maximum size during puberty and gradually diminishes in size in the adult.

The thymus gland is large in children. In the newborn, it is often larger than the heart. It gradually decreases in size with increasing age and is replaced by mediastinal fat.

6 ,QWHUQDOFDURWLG DUWHU\

5LJKWFRPPRQ FDURWLGDUWHU\

([WHUQDOFDURWLG DUWHU\

/HIWFRPPRQ FDURWLGDUWHU\ 7K\URLG JODQG

%UDFKLRFHSKDOLF DUWHU\

5

325

/HIW EUDFKLRFHSKDOLFYHLQ

5LJKW EUDFKLRFHSKDOLF YHLQ

$RUWLF DUFK

6XSHULRU YHQDFDYD

3XOPRQDU\ WUXQN 3XOPRQDU\YHLQV

%URQFKL

%URQFKL

7K\PXV JODQG

,

$SH[RI KHDUW

FIG. 6.26  Anterior view of thymus gland.

/

CHAPTER 6   Thorax

326

Thymus gland

Sternum A

Aortic arch

R

L

Superior vena cava

P

FIG. 6.27  Axial, T1-weighted MRI of pediatric chest with thymus gland.

A Sternum Thymus gland Ascending aorta

Pulmonary trunk L

R Superior vena cava

Left pulmonary artery

Lower paratracheal lymph nodes

Descending aorta

Carina Esophagus

P

FIG. 6.28  Axial CT of thymus gland.

CHAPTER 6   Thorax

Trachea and Esophagus Throughout its course in the mediastinum, the trachea runs anterior to the esophagus. Considered an elastic tube, the trachea is reinforced by approximately 16–20 C-shaped pieces of cartilage that maintain an open passageway for air. The cartilages are closed posteriorly by elastic connective tissue that allows for the

Right brachiocephalic vein

Brachiocephalic trunk A

327

passage of food through the esophagus. In crosssection, the trachea appears as a round, air-filled structure to the point at which it bifurcates at the carina (Figs. 6.10, 6.11, 6.18, and 6.25). The esophagus appears as an oval-shaped structure that descends through the mediastinum to enter the abdominal cavity at the esophageal hiatus of the diaphragm (Figs. 6.29 and 6.30).

Left brachiocephalic vein

Left common carotid artery

Trachea

Left subclavian artery L

R Esophagus

P

FIG. 6.29  Axial, T1-weighted MRI of trachea and esophagus.

/HIW EUDFKLRFHSKDOLF YHLQ

%UDFKLRFHSKDOLF WUXQN $

6WHUQXP

/HIWFRPPRQ FDURWLGDUWHU\

5

/

5LJKW EUDFKLRFHSKDOLF YHLQ

7UDFKHD

3

FIG. 6.30  Axial CT of trachea and esophagus.

(VRSKDJXV

/HIW VXEFODYLDQ DUWHU\

328

CHAPTER 6   Thorax

LYMPHATIC SYSTEM Lymph Nodes

cross-section unless they are enlarged as a result of an abnormality (Figs. 6.28, 6.32, and 6.33).

Lymph nodes in the mediastinum are generally clustered around the great vessels, esophagus, bronchi, and carina. Mediastinal lymph nodes are classified according to their location and are grouped into 14 regional nodal stations for use in lung cancer staging (Fig. 6.31 and Table 6.3). Lymph vessels and nodes can be difficult to visualize in

The supraclavicular lymph nodes are commonly referred to as the sentinel lymph nodes because their enlargement alerts the medical professional to the possibility of malignant disease in the thoracic and/or abdominal cavities.

Thyroid cartilage Trachea

1L

1R

Clavicle Manubrium

Aortic arch 2R

SVC

2L

13R

4R

12R

4L 13L 10L

10R

11R

Carina 13R

12L 11L 12L

7 14R

Left main pulmonary artery

14L

14R

12R

13L 8

8

Esophagus

14L

9

9

8

8

Esophagus 6 3P

3A

Aortic arch

7

Left main pulmonary artery

5 Trachea SVC

FIG. 6.31  Coronal view with distribution of mediastinal lymph nodes. L, left; R, right; 1, highest mediastinal nodes; 2, upper paratracheal nodes; 3, prevascular and retrotracheal nodes; 4, lower paratracheal (including azygos) nodes; 5, subaortic nodes; 6, para-aortic nodes; 7, subcarinal; 8, paraesophageal nodes; 9, pulmonary ligament; 10, hilar nodes; 11, interlobar nodes; 12, lobar nodes; 13, segmental nodes; 14, segmental nodes.

CHAPTER 6   Thorax TABLE 6.3

329

International Association for the Study of Lung Cancer (IASLC) Lymph Node Map 2009

Supraclavicular Nodes 1 Station 1: Low Cervical, Supraclavicular, and Sternal Notch; Divided Into 1R and 1L by Trachea 1R—extend from lower border of cricoid cartilage to clavicles and upper margin of manubrium 1L—extend from lower border of cricoid cartilage to clavicles and upper margin of manubrium Superior Mediastinal Nodes 2–4 Station 2: Upper Paratracheal; Divided into 2R and 2L by Lateral Border of Trachea 2R—upper border: apex of R lung to upper border of manubrium; lower border: intersection of L brachiocephalic vein with trachea 2L—upper border: apex of L lung to upper border of manubrium; lower border: superior border of aortic arch Station 3: Prevascular (Anterior to the Vessels) and Retrotracheal (Posterior to the Esophagus) 3A—prevascular: on right side: apex of chest to level of carina and posterior sternum to anterior border of SVC. On left side: apex of chest to level of carina and posterior sternum to left carotid artery 3P—retrotracheal: apex of chest to carina Station 4: Lower Paratracheal; Divided Into 4R and 4L by Trachea 4R—upper border: intersection of caudal margin of left brachiocephalic vein; lower border: lower border of azygos vein 4L—upper border: upper margin of aortic arch; lower border: upper margin of left main pulmonary artery Aortic Nodes 5–6 Station 5: Subaortic; Lateral to Ligamentum Arteriosum 5—subaortic (aortopulmonary window): upper border: lower margin of aortic arch; lower border: upper rim of left main pulmonary artery Station 6: Para-Aortic; Anterior and Lateral to Ascending Aorta and Aortic Arch 6—para-aortic (ascending aorta or phrenic): upper border: upper margin of aortic arch; lower border: lower margin of aortic arch Inferior Mediastinal Nodes 7–9 Station 7: Subcarinal; Located Caudally to Carina 7—on right: extend caudally to lower border of bronchus intermedius; on left: extend caudally to upper margin of the lower lobe bronchus Station 8: Paraesophageal; Below Carinal Nodes, Adjacent to Wall of Esophagus 8—on right: upper border: lower margin of bronchus intermedius; lower border: interlobar region. On left: upper margin of lower lobe bronchus; lower border: interlobar region. Station 9: Pulmonary Ligament 9—upper border: inferior pulmonary vein; lower border: diaphragm Hilar, Lobar, and Subsegmental Nodes 10–14 Station 10: Hilar; Adjacent to Mainstem Bronchus and Hilar Vessels 10—on right: upper border: lower rim of azygos vein; lower border: interlobar region. On left: upper border: upper rim of pulmonary artery; lower border: interlobar region. Station 11: Interlobar; Between Origins of the Lobar Bronchi 11—superior: between upper lobe bronchus and bronchus intermedius on the right; inferior: between the middle and lower lobe bronchi on the right Station 12: Lobar; Adjacent to Lobar Bronchi Station 13: Segmental; Adjacent to Segmental Bronchi Station 14: Subsegmental; Adjacent to Subsegmental Bronchi L, Left; R, right.

330

CHAPTER 6   Thorax

Ascending aorta

Enlarged mediastinal lymph nodes

A

Superior vena cava

R

L

Carina Descending aorta

P

FIG. 6.32  Axial, T1-weighted MRI of chest with enlarged lymph nodes.

Enlarged mediastinal lymph nodes

Clavicle

Trachea

A

R

L

Right lung

P

Esophagus

FIG. 6.33  Axial CT of chest with enlarged lymph nodes.

CHAPTER 6   Thorax

to the diaphragm at the level of L2 and passes from the abdominal cavity into the thorax through the aortic hiatus of the diaphragm. It originates in the abdomen, at the cisterna chyli, a dilated sac or confluence of lymph trunks into which lymph from the intestinal and lumbar lymphatic trunks open (Fig. 6.34). It ascends the thorax, between the azygos vein and the descending aorta, and empties into the left subclavian vein at the level of the clavicle. The smaller right lymphatic duct collects lymph from the right upper side of the body and is formed by the merging of various lymphatic trunks near the right clavicle. This duct empties into the right subclavian vein (Fig. 6.34).

Lymph Vessels The lymphatic system consists of a network of lymphatic vessels that carry lymph fluid (excess interstitial fluid) away from the tissue and into venous circulation. Small lymph vessels (capillaries) can be found accompanying arteries and veins throughout the body. The tiny lymph vessels increase in size until they reach their terminal collecting vessels, the thoracic duct and the right lymphatic duct. The thoracic duct is the main vessel of the lymph system, draining all of the lymph fluid from tissues below the diaphragm and from the left side of the body above the diaphragm (Figs. 6.34–6.36). It begins inferior

Left brachiocephalic vein Bronchomediastinal Right jugular trunk trunk Right internal jugular vein Right lymphatic duct

331

Left jugular trunk

S Left internal jugular vein Left subclavian trunk

Right subclavian vein Right brachiocephalic vein

Left subclavian vein

Internal mammary

Right subclavian trunk Superior vena cava

Thoracic duct

R

L

Cisterna chyli

Twelfth thoracic vertebra

Intestinal lymph vessels First lumbar vertebra Testicular lymph vessels

Right and left lumbar trunks

Lower extremity lymph vessels

I

FIG. 6.34  Anterior view of thoracic and right lymphatic ducts.

CHAPTER 6   Thorax

332

A

Esophagus

Thoracic duct Azygos vein

Descending aorta

R

L Hemiazygos vein

Thoracic vertebra

P

FIG. 6.35  Axial CT of azygos vein and thoracic duct.

S

Azygos vein R

L Descending aorta

Diaphragm Thoracic duct

Spleen

Liver Right crus of diaphragm I

FIG. 6.36  Coronal CT reformat of thoracic duct.

CHAPTER 6   Thorax

HEART AND VASCULATURE Superficial Landmarks The heart is a hollow, four-chambered muscular organ located within the middle mediastinum. It is approximately the size of a large clenched fist and is situated obliquely in the chest with one-third of its mass lying to the right of the median plane and two-thirds to the left. The heart can be described as being roughly trapezoid shaped (Fig. 6.37). The superficial relationships of the heart include the base, apex, three surfaces (sternocostal, diaphragmatic, pulmonary), and four borders (right, inferior, left, and superior). The broad base (posterior aspect) is the most superior and posterior portion of the heart. It is formed by both atria, primarily the left atrium, and gives rise to the great vessels. The apex is formed by the left ventricle and points inferiorly, anteriorly, and to the left. It is located at the level of the fifth

333

intercostal space, just medial to the midclavicular line. The sternocostal (anterior) surface is formed primarily by the right atrium and right ventricle with a small contribution from the left ventricle. The diaphragmatic (inferior) surface rests on the central tendon of the diaphragm and is formed by both ventricles and a small portion of the right atrium. The pulmonary (left) surface is formed mainly by the left ventricle and fills the cardiac notch of the left lung. The borders of the heart represent the external surfaces of the cardiovascular silhouette in radiographic profile. The borders include the right border, formed by the right atrium and located between the superior and inferior venae cavae; the left border, formed by the apex of the heart or the left ventricle; the superior border, formed by the right and left atria; and the inferior border, which is formed primarily by the right ventricle, with a small contribution from the left ventricle (Figs. 6.37–6.39).

Base

Pulmonary semilunar valve

Pulmonary (left) surface Aortic semilunar valve

Bicuspid valve

Tricuspid valve

Apex Diaphragmatic (inferior) surface

FIG. 6.37  Superficial landmarks of the heart.

334

CHAPTER 6   Thorax Base posterior aspect

S

Superior border

Ascending aorta

Pulmonary trunk Pericardium R

L Pulmonary surface Myocardium Apex left border

Right border

I

Right atrium

Inferior border and diaphragmatic surface

Left ventricle

FIG. 6.38  Coronal, T1-weighted MRI of surfaces and borders of the heart.

S

Base

Clavicle

Pulmonary trunk Descending aorta Left coronary artery Left mainstem bronchus

Pulmonary semilunar valve

Left pulmonary vein P

A Sternocostal (anterior) surface

Left atrium Left ventricle

Right ventricle

Interventricular septum

Diaphragmatic (inferior) surface

Myocardium

I

FIG. 6.39  Sagittal, T1-weighted MRI of surfaces and borders of the heart.

CHAPTER 6   Thorax

335

Table 6.4). These spaces can be filled with fluid and may be mistaken for cystic lesions or lymphadenopathy. Located between the parietal pericardium and the heart wall is a layer of epicardial fat that is typically more prominent near the inflow and outflow of the heart, the coronary vessels, and along the grooves separating the heart chambers. Mediastinal fat is the fat present within the thoracic cavity external to the parietal pericardium (Figs. 6.40–6.42).

Pericardium The heart is enclosed in a pericardial sac that surrounds the heart and the proximal portions of the great vessels entering and leaving the heart (Figs. 6.40–6.42). The fibrous pericardium is attached to the central tendon of the diaphragm and is pierced by the inferior vena cava. The inner surface of the fibrous pericardium consists of a double-layered serous membrane termed the serous pericardium. The serous pericardial layers include the parietal layer, which lines the inner surface of the fibrous pericardium, and the visceral layer (epicardium), which covers the outer surface of the heart and the roots of the great vessels. Located between the two layers is a potential space (pericardial cavity) containing a thin film of serous fluid that acts as a lubricant to reduce friction to the tissues caused by heart movements. During embryonic development, the heart invaginates into the serous pericardium, which creates folds called pericardial reflections. The pericardial reflections located by the great vessels result in the formation of two potential spaces: the oblique and transverse sinuses. Within the two sinuses are potential spaces called recesses (Fig. 6.43 and

Pericarditis is an inflammation of the pericardium. It usually develops suddenly and may last for several months. Symptoms include sharp stabbing chest pain that may increase with coughing and swallowing as well as difficulty breathing when lying down. Most cases of pericarditis occur in men aged 20–50. Although there can be many causes of pericarditis, it is frequently due to complications of an infection (viral, bacterial, fungal, or parasitic). Left untreated, it can become a life-threatening condition called cardiac tamponade, a build-up of fluid causing a severe compression of the heart. Treatment depends on the cause but may include pain medication, antibiotics, and anti-inflammatories.

S

Epicardial fat

Pericardial cavity containing pericardial fluid

Cut edge of epicardium (visceral pericardium) R

L Cut edge of parietal pericardium

Fibrous pericardium attachment to central tendon of diaphragm

I

FIG. 6.40  Anterior view of heart with pericardium.

336

CHAPTER 6   Thorax Tricuspid valve

Mediastinal fat Pericardium

Epicardial fat

A

Right ventricle

Right ventricle Interventricular septum Left ventricle

L

R

Bicuspid valve

P

Interatrial septum

Left atrium

FIG. 6.41  Axial, T1-weighted MRI of heart with pericardium.

Mediastinal fat

Right ventricle

A Pericardium Epicardial fat Myocardium

L

R

Liver

Interventricular septum

P

FIG. 6.42  Axial CT of heart with pericardium.

Left ventricle

CHAPTER 6   Thorax

337

S Superior vena cava

Ascending aorta Pulmonary trunk

Superior aortic recess

Left pulmonary veins

Right pulmonic recess Postcaval recess

R

L

Transverse sinus

Left pulmonic recess Left pulmonary venous recess

Right pulmonary venous recess

Oblique sinus

Inferior vena cava

A

I Ascending aorta

Superior aortic recess (right lateral portion)

Superior aortic recess (anterior portion)

A

Superior vena cava

Main pulmonary artery R

Right superior pulmonary vein

L

Superior aortic recess (posterior portion)

Left pulmonic recess Left superior pulmonary vein

Right pulmonary artery

Left intermediate bronchus

Right intermediate bronchus Descending aorta

Posterior pericardiac recess Esophagus

B P

FIG. 6.43  Pericardial sinuses and recesses. (A) Anterior view of pericardial sinuses and recesses. (B) Axial view of pericardial sinuses and recesses.

TABLE 6.4

Pericardial Sinuses and Recesses

Transverse sinus Superior aortic recess Inferior aortic recess Right and left pulmonic recesses Oblique sinus Posterior pericardial recess

Located posterior to ascending aorta and pulmonary trunk, extending to left atrium Located anterior to ascending aorta and pulmonary trunk; partially surrounds ascending aorta Located between right lateral ascending aorta and right atrium; posterior to aorta and anterior to left atrium Right; inferior to proximal right pulmonary artery Left; inferior to left pulmonary artery, superior to left superior pulmonary vein Located posterior to left atrium and inferior to the transverse sinus Extends superiorly behind the right pulmonary artery, medial to the intermediate bronchus

338

CHAPTER 6   Thorax surfaces of the heart, termed the anterior and posterior interventricular grooves (Fig. 6.45; see coronary vessels, page 339).

Heart Wall The walls of the heart consist of three layers: (1) epicardium, the thin outer layer that is consistent with the visceral layer of the pericardium; (2) myocardium, the thick middle layer consisting of strong cardiac muscle; and (3) endocardium, the thin, endothelial layer lining the inner surface (Figs. 6.39, 6.42, and 6.44). The endothelial layer also lines the valves of the heart and is continuous with the inner lining of the blood vessels. The heart is divided into four chambers: the right and left atria and the right and left ventricles. The two superior collecting chambers called atria are separated by the interatrial septum (Figs. 6.6, 6.41, and 6.44). During embryonic development, an oval opening exists within the interatrial septum called the foramen ovale. This opening allows blood flow between the right and left atria during fetal lung development. At birth, the foramen ovale closes, leaving a small depression in the septal wall called the fossa ovalis in the adult heart (Fig. 6.44). The two inferior pumping chambers called ventricles are divided by the interventricular septum (Figs. 6.39, 6.41, 6.42, and 6.44). On the external surface of the heart are grooves that separate the chambers. The atria of the heart are separated from the ventricles by the coronary groove (atrioventricular groove or sulcus). The ventricles of the heart are separated by two depressions or sulci that are located on the anterior and posterior

SVC

Chambers The right atrium forms the right border of the heart and receives deoxygenated blood from the body via the superior and inferior venae cavae and from the coronary sinus and cardiac veins that drain the myocardium (Fig. 6.44). A small muscular embryonic appendage, the right auricle, projects upward and toward the left, covering the root of the aorta (Fig. 6.45). The right ventricle lies on the diaphragm and comprises the largest portion of the anterior surface of the heart. It receives deoxygenated blood from the right atrium and forces it into the pulmonary trunk for conveyance to the lungs. Extending from the inner surface of the ventricular walls are three conical-shaped projections of cardiac muscle called papillary muscles, which anchor the cusps of the tricuspid valve to the right ventricle (Fig. 6.44). The left atrium lies posterior to the right atrium and is the most posterior surface of the heart. It also has an embryonic appendage, the left auricle, which projects to the left of the pulmonary trunk over the superior surface of the heart (Fig. 6.45). The left atrium receives oxygenated blood directly from the lungs via the four pulmonary veins (two on each side). The left ventricle forms the apex, left

S Interatrial septum

Atrioventricular node

Sinoatrial node

Fossa ovalis

Bicuspid (mitral) (left atrioventricular) valve

Right atrium Left atrium

R

Tricuspid (right atrioventricular) valve

L

Endocardium

Papillary muscle Myocardium

Atrioventricular bundle (bundle of His)

Left ventricle

Chordae tendinae Right ventricle Papillary muscle Epicardium

Right bundle branch

Left bundle branch

I Interventricular septum

FIG. 6.44  Coronal view of heart wall, chambers, and conduction system.

CHAPTER 6   Thorax

339

S Ascending aorta

Aortic arch Right pulmonary artery

Superior vena cava

Pulmonary trunk

Root of aorta R

Left atrial appendage L

Left main coronary artery

Pulmonary veins

Base of heart

Right atrial appendage Right coronary artery

Epicardial fat in anterior interventricular groove

Right atrium

Left anterior descending artery

Coronary groove (atrioventricular groove) Right ventricle

Left ventricle I Apex of heart

FIG. 6.45  Anterior view of heart surface.

border, and most of the inferior surface of the heart. It receives oxygenated blood from the left atrium and pumps it into the aorta for distribution throughout the systemic vascular circuit. The myocardium of the left ventricle is normally three times thicker than that of the right ventricle, reflecting the force necessary to pump blood to the distant sites of the systemic circulation (Figs. 6.46–6.66). Two papillary muscles project from the ventricular walls to anchor the bicuspid valve to the left ventricle (Figs. 6.44, 6.52, 6.65, and 6.66). To see the cardiac chambers in off-axis views, refer to pages 380–388.

Cardiac Conduction System The cardiac conduction system is the electrical system that controls the heart rate by generating electrical impulses and conducting them throughout the muscles of the heart,

stimulating the heart to contract and pump blood. The electrical impulses of the myocardium travel through a specific nerve pathway in the heart beginning in the sinoatrial (SA) node, which is a mass of specialized cardiac muscle fibers that act as the “pacemaker” of the heart. The SA node lies under the epicardium in the superior aspect of the right atrium. The electrical signal generated from the SA node travels to the right and left atrium, causing them to contract and force blood into the ventricles. The electrical signal continues to the ventricles via the atrioventricular (AV) node, located in the posteroinferior region of the interatrial septum near the opening of the coronary sinus, and then to the atrioventricular (AV) bundle (bundle of His) located along the interventricular septum. The signal continues down the bundle and into the right and left bundle branches. When the signal reaches the bundle branches, it causes the ventricles to contract and force blood to the body and lungs (Fig. 6.44). (Text continues on page 348)

CHAPTER 6   Thorax

340

Right atrium

A

Right ventricle

Pericardium

Ascending aorta

L

R Right pulmonary vein Esophagus

P

Azygos vein

Descending aorta

FIG. 6.46  Axial, T1-weighted MRI of right ventricle.

Superior vena cava

Right atrium

Ascending aorta

A

Pulmonary trunk

R

L

Right pulmonary vein

Left atrium

P

Descending aorta

Left ventricle

FIG. 6.47  Axial CT of right ventricle.

Left atrium

CHAPTER 6   Thorax Pericardium

341

Epicardial fat

A

Right ventricle

Tricuspid valve Left ventricle

Right atrium L

R

Bicuspid valve Left atrium Descending aorta Left atrium P

FIG. 6.48  Axial, T1-weighted MRI of left atrium.

Right middle lobe

Costal cartilage

Ascending aorta A

Body of sternum

Right ventricle Left superior lobe

Rib

Left ventricle

Right atrium Left atrium R

L Left inferior pulmonary vein

Right Angle Right Thoracic inferior of rib inferior vertebra lobe pulmonary vein

FIG. 6.49  Axial CT of left atrium.

P

Head of rib

Neck of rib

Left inferior lobe

CHAPTER 6   Thorax

342

Right ventricle

Left ventricle

A

Interventricular septum Right atrium

R

L

Coronary sinus

Descending aorta

Esophagus

Hemiazygos vein

Azygos vein

P

FIG. 6.50  Axial, T1-weighted MRI of right atrium.

Right atrium

Aortic semilunar valve

A

Right ventricle

Left ventricle

Interatrial septum

R

L

Right inferior pulmonary vein

Left atrium

P

Descending aorta

Left inferior pulmonary vein

FIG. 6.51  Axial CT of right atrium.

CHAPTER 6   Thorax Right ventricle

Tricuspid valve

Papillary muscle

A

Interventricular septum

343

Left ventricle

Right atrium

Myocardium

L

R

Papillary muscle

Interatrial septum

Bicuspid valve

Left atrium P

FIG. 6.52  Axial, T1-weighted MRI with four-chamber view of heart.

Right atrium

Tricuspid valve

A

Right ventricle

Left ventricle

Interatrial septum

R

L

Left atrium

P

FIG. 6.53  Axial CT with four-chamber view of heart.

Descending aorta

Bicuspid valve

344

CHAPTER 6   Thorax

Right atrium

Right ventricle

Coronary sinus

A

Interventricular septum

Left ventricle

R

L

P

Inferior vena cava

Descending aorta

FIG. 6.54  Axial, T1-weighted MRI of ventricles.

Right ventricle

A

Interventricular septum

Left ventricle

Coronary groove R

L

Inferior vena cava

Descending P aorta

Esophagus

FIG. 6.55  Axial CT of ventricles.

CHAPTER 6   Thorax S

Anterior interventricular groove

Left anterior descending artery Papillary muscle A

P Left ventricle

Right ventricle

Diaphragm

Liver

I

Interventricular septum

FIG. 6.56  Sagittal, T1-weighted MRI of ventricles.

Right atrial appendage

S

A

P

Right ventricle

Diaphragm

Interventricular septum

I

Left ventricle

FIG. 6.57  Sagittal CT reformat of ventricles.

345

CHAPTER 6   Thorax

346

S

Pulmonary trunk Ascending aorta

Left ventricle

A

P

Right coronary artery Descending aorta Right atrium IVC Liver

I

FIG. 6.58  Sagittal, T1-weighted MRI of heart with pulmonary trunk.

Right pulmonary Aortic arch artery

S

Pulmonary trunk

Left mainstem broncus

Right ventricular outflow tract

Left pulmonary veins

A

P Descending aorta

Aortic semilunar valve

Right ventricle

I

Left atrium

FIG. 6.59  Sagittal CT reformat of heart with pulmonary trunk.

CHAPTER 6   Thorax S

Aortic arch

Left brachiocephalic vein

Left mainstem bronchus

Right pulmonary artery

Descending aorta

A

P Left atrium

Ascending aorta

Interatrial septum

Right atrium IVC Liver I

FIG. 6.60  Sagittal, T1-weighted MRI of heart with left atrium.

Left brachiocephalic artery S

Right pulmonary artery

Esophagus Left mainstem bronchus

Ascending aorta

Left atrium A

P

Right ventricle

Descending aorta I

FIG. 6.61  Sagittal CT reformat of heart with left atrium.

347

348

CHAPTER 6   Thorax

Cardiac Valves Four valves are located in the heart that function to maintain one-way directional blood flow throughout the heart. The valves can be divided into two groups: atrioventricular and semilunar (Figs. 6.44 and 6.62).

Atrioventricular Valves.  The two atrioventricular

valves are found at the entrances to both ventricles and function to prevent backflow of blood between the atria and ventricles during ventricular contraction. These valves have leaflets that are attached to the papillary muscles by thin cords of fibrous tissue called chordae tendineae. The right atrioventricular valve, with three

leaflets, is called the tricuspid valve, and the left atrioventricular valve, with two leaflets, is called the bicuspid (mitral) valve (Figs. 6.44, 6.52, 6.53, and 6.63).

Semilunar Valves.  The semilunar valves are located at the junction where the ventricles meet the great vessels and separate the ventricles from the circulatory system. These valves are called semilunar because of their three crescentshaped cusps, and they function to prevent the flow of blood back into the ventricles during ventricular relaxation. The pulmonary semilunar valve is located at the juncture of the right ventricle and pulmonary artery, and the aortic semilunar valve lies between the left ventricle and ascending aorta (Figs. 6.62, 6.63, 6.65, and 6.66).

Left common carotid artery

Brachiocephalic trunk

Left subclavian artery S Aorta

Pulmonary artery

Pulmonary veins

Superior vena cava

Left atrium Bicuspid (mitral) (left atrioventricular) valve

Pulmonary semilunar valve

L Aortic semilunar valve

R Right atrium

Left ventricle Endocardium

Tricuspid (right atrioventricular) valve

Myocardium Epicardium

Inferior vena cava I Right ventricle Interventricular septum

FIG. 6.62  Coronal view of heart with four chambers and cardiac valves.

CHAPTER 6   Thorax Fibrous ring of pulmonary trunk

Anterior cusp of pulmonary semilunar valve

A

Right cusp of pulmonary semilunar valve

Left cusp of pulmonary semilunar valve

Right cusp of aortic semilunar valve

Left cusp of aortic semilunar valve Bicuspid valve

Fibrous ring of aorta R

L

Tricuspid valve

Location of atrioventricular bundle

P

Posterior cusp of aortic semilunar valve

Superior view

FIG. 6.63  Superior view of heart valves.

Left brachiocephalic vein

Ascending aorta Pulmonary trunk

Right atrium

Left ventricle

Right ventricle

Epicardium

FIG. 6.64  Coronal, T1-weighted MRI of heart.

349

350

CHAPTER 6   Thorax S

Clavicle Ascending aorta Superior vena cava Pulmonary trunk

Left aortic sinus

Aortic semilunar valve

R

L

Right aortic sinus

Left ventricle Papillary muscle

Right atrium I

FIG. 6.65  Coronal, T1-weighted MRI of heart with aortic semilunar valve.

Ascending aorta

Left coronary artery

S

Pulmonary trunk Left aortic sinus

Superior vena cava

Aortic semilunar valve

Right aortic sinus

Papillary muscle R

L Left ventricle

Right atrium Right coronary artery

Right ventricle

I

FIG. 6.66  Coronal CT reformat of heart with aortic semilunar valve.

CHAPTER 6   Thorax

gives rise to the right coronary artery, and the left aortic sinus gives rise to the left coronary artery (Figs. 6.65– 6.69). Because no vessels arise from the posterior aortic sinus, it is considered to be noncoronary. The ascending aorta curves superiorly and posteriorly as the aortic arch over the right pulmonary artery and left mainstem bronchus (Figs. 6.59, 6.60, 6.67, 6.68, and 6.70–6.74). The top of the aortic arch is approximately at the level of T3. The arch continues as the descending aorta posterior to the left mainstem bronchus and pulmonary trunk, on the left side of the vertebral body of T4 (Figs. 6.59, 6.60, and 6.72–6.74). The descending aorta passes slightly anterior and to the left of the vertebral column as it

GREAT VESSELS Blood travels to and from the heart through the great vessels, which include the aorta, pulmonary arteries and veins, and superior and inferior venae cavae (Figs. 6.67 and 6.68). The aorta is the largest artery in the body and can be divided into the ascending aorta, aortic arch, and descending aorta. The ascending aorta begins at the base of the left ventricle. The origin of the ascending aorta (aortic root) is divided into three dilations or protrusions that create spaces termed aortic sinuses, one left, one right, and one posterior, which correspond to the three cusps of the aortic semilunar valve. The right aortic sinus

Left common carotid artery

S

Left subclavian artery Left brachiocephalic vein

Brachiocephalic trunk

Arch of aorta Ascending aorta

Right brachiocephalic vein

Ligamentum arteriosum Left pulmonary artery

Superior vena cava

Pulmonary trunk Right pulmonary arteries

L

R Right pulmonary veins

Superior

Superior

Inferior

Left pulmonary veins Left atrial appendage

Inferior Aortic root Right atrial appendage

Circumflex artery

Anterior cardiac veins

Great cardiac vein

Right border of heart Right atrium

Left marginal artery

Right coronary artery

Left anterior descending artery

Coronary groove

Left ventricle

Small cardiac vein Left border of heart Right marginal artery Anterior interventricular groove

Inferior vena cava Right ventricle

351

Apex of heart I

Inferior border of heart

FIG. 6.67  Anterior view of heart and great vessels.

352

CHAPTER 6   Thorax Left common carotid artery

Inferior thyroid vein S

Left subclavian artery Left brachiocephalic vein

Brachiocephalic trunk Right brachiocephalic vein

Arch of aorta

Superior vena cava

Ascending aorta

Azygos vein R

Left pulmonary artery Left pulmonary veins

Superior

L

Right pulmonary arteries

Inferior Left atrium

Superior

Oblique vein of left atrium

Inferior

Right pulmonary veins

Great cardiac vein Circumflex artery

Right atrium Coronary sinus

Left posterior interventricular vein

Inferior vena cava Small right cardiac vein Right coronary artery Posterior atrioventricular groove Coronary groove Middle cardiac vein

Left ventricle

Posterior interventricular artery I Anterior interventricular artery

Right ventricle

FIG. 6.68  Posterior view of heart and great vessels.

descends through the thoracic cavity and into the abdomen via the aortic hiatus of the diaphragm. In the thoracic cavity, the descending aorta is commonly called the thoracic aorta, and in the abdominal cavity, it is called the abdominal aorta. The pulmonary trunk, the main pulmonary artery, lies entirely within the pericardial sac. It arises from the right ventricle and ascends in front of the ascending aorta. Then it courses posteriorly and to the left, where it bifurcates at the level of the sternal angle (T4) into the right and left pulmonary arteries (Figs. 6.67, 6.68, and 6.75–6.78). At the origin of the pulmonary trunk are slight dilations between the wall of the pulmonary trunk and cusps of the pulmonary semilunar valves, termed pulmonary sinuses (Fig. 6.69). The pulmonary trunk is attached to the aortic arch by a fibrous cord called the ligamentum arteriosum, the remnant of an important fetal blood vessel (ductus arteriosus) that links the

pulmonary and systemic circuits during fetal development (Figs. 6.67 and 6.75). The right pulmonary artery courses laterally, posterior to the ascending aorta and superior vena cava, and anterior to the esophagus and right mainstem bronchus, to the hilum of the right lung (Figs. 6.15A, 6.67, and 6.75). It then divides into two branches, with the lower branch supplying the middle and inferior lobes and the upper branch supplying the superior lobe (Figs. 6.75–6.80). The left pulmonary artery, shorter and smaller than the right, is also the most superior of the pulmonary vessels. It travels horizontally, arching over the left mainstem bronchus, and enters the hilum of the left lung just superior to the left mainstem bronchus (Figs. 6.15B and 6.75–6.82). Within the lungs, each pulmonary artery descends posterolateral to the secondary bronchi and divides into lobar and segmental arteries, continuing to branch out and follow along with the smallest divisions of the bronchial tree (Figs. 6.75 and 6.76–6.82).

CHAPTER 6   Thorax Left aortic sinus

353

S

Posterior aortic sinus

Pulmonary trunk

Aortic root Pulmonary sinuses

Left coronary artery

L

R Right ventricle

Left ventricle

I

FIG. 6.69  3D CT of pulmonary trunk and left ventricle.

Located inferior to the pulmonary arteries are the four pulmonary veins, two each (superior and inferior), extending from each lung to enter the left atrium (Figs. 6.67, 6.68, 6.75, 6.76, and 6.79–6.86). They begin as a capillary network along the walls of the alveoli, where they merge with the capillaries of the pulmonary arteries. The venous capillaries successively combine to form a single trunk for each lobe: three for the right and two for the left lung. Frequently, the trunk from the middle lobe of the right lung unites with the trunk from the upper lobe, forming just two trunks on the right side before entering the left atrium. The right superior pulmonary vein collects blood from the upper-lobe segments of the right lung and passes anterior and inferior to the right pulmonary artery, behind the superior vena cava

(Figs. 6.79, 6.80, 6.83, and 6.84). The right inferior pulmonary vein receives blood from the lower lobes of the right lung and crosses behind the right atrium to the left atrium (Figs. 6.75, 6.76, 6.81, 6.82, and 6.87–6.89). The left superior pulmonary vein receives blood from the left upper lobe of the left lung and courses anterior and inferior to the left main bronchus as it enters the left atrium (Figs. 6.81 and 6.90–6.92). The left inferior pulmonary vein drains the inferior lobe of the left lung and passes toward the left atrium anterior to the bronchi (Figs. 6.75, 6.76, 6.79, 6.81, 6.85, 6.86, and 6.90–6.92). The pulmonary veins course more horizontally than the pulmonary arteries and are ultimately oriented toward the left atrium. At the hilum of the lungs, the pulmonary veins are anterior and inferior to the pulmonary arteries,

354

CHAPTER 6   Thorax Internal mammary vessels

Sternum

Superior vena cava Aortic arch Trachea Esophagus

Thoracic vertebra

FIG. 6.70  Axial, T1-weighted MRI of chest with aortic arch.

Superior vena cava

Aortic arch

A

L

R

Trachea

FIG. 6.71  Axial CT of chest with aortic arch.

P

Thoracic vertebra

Esophagus

Superior vena cava

Ascending aorta

A

Superior vena cava

Descending aorta

Ascending aorta

A

Left mainstem bronchus

R

L

L

R

Left pulmonary artery

Carina of trachea

P

Esophagus

FIG. 6.72  Axial, T1-weighted MRI of chest with ascending and descending aorta.

Right mainstem bronchus

Carina

P

Descending aorta

FIG. 6.73  Axial CT of chest with ascending and descending aorta.

Aortic root

Right pulmonary artery S

Aortic arch Left mainstem bronchus

P

A

Thoracic vertebra

Right ventricle

Left atrium

I

Descending aorta

FIG. 6.74  Sagittal, T1-weighted MRI of aortic arch and descending aorta.

356

CHAPTER 6   Thorax S

Trachea Right pulmonary artery

Arch of aorta

Right mainstem bronchus

Ligamentum arteriosum Left mainstem bronchus Left pulmonary artery

Right superior and inferior pulmonary veins

Pulmonary trunk R

L Left superior and inferior pulmonary veins

Superior vena cava

Aorta I Inferior vena cava

FIG. 6.75  Anterior view of pulmonary arteries and veins. Left ascending pulmonary artery Left pulmonary artery

Pulmonary trunk

S

Ascending aorta SVC Right pulmonary artery

Left descending pulmonary artery

Right ascending pulmonary artery Right descending (interlobar) pulmonary artery

Peripheral pulmonary arteries

Right superior pulmonary vein L

R

Left inferior pulmonary vein

Right inferior pulmonary vein Right atrium

Descending aorta

I

Left atrium

IVC

FIG. 6.76  3D CT of pulmonary arteries and veins, posterior view.

CHAPTER 6   Thorax

357

Ascending aorta Superior vena cava

Pulmonary trunk Left pulmonary artery

Right pulmonary artery

Left mainstem bronchus

Right mainstem bronchus

Descending aorta

Azygos vein Esophagus

FIG. 6.77  Axial, T1-weighted MRI of chest with pulmonary trunk.

Superior vena cava

A

Ascending aorta

Pulmonary trunk

Left superior pulmonary vein L

R

Left pulmonary artery

Right mainstem bronchus

Left mainstem bronchus Right pulmonary artery

Azygous vein

P

Descending aorta

FIG. 6.78  Axial CT of chest with pulmonary trunk.

which are located anterior to the bronchi (Figs. 6.75, 6.78, and 6.87). The superior and inferior venae cavae are the largest veins of the body. The superior vena cava is formed by the junction of the brachiocephalic veins, posterior to

the right first costal cartilage, and carries blood from the thorax, upper limbs, head, and neck (Figs. 6.26 and 6.34). As it travels inferiorly, it is located posterior and lateral to the ascending aorta before entering the upper portion of the right atrium (Figs. 6.65, 6.67, 6.68, and 6.70–6.73).

CHAPTER 6   Thorax

358

Right common carotid artery

S

Left common carotid artery

Left subclavian artery

Brachiocephalic artery Ascending aorta

Left pulmonary artery L

Right ascending pulmonary artery R Right pulmonary artery

Left superior pulmonary vein

Right descending (interlobar) pulmonary artery

Left inferior pulmonary vein

Right superior pulmonary vein Right inferior pulmonary vein Left atrium

Descending aorta I

FIG. 6.79  MRA of pulmonary vessels.

Right pulmonary artery

S

Aortic arch

Left mainstem bronchus

Left pulmonary artery Left ascending pulmonary artery

Right descending pulmonary artery

Left descending pulmonary artery

Right superior pulmonary vein

Left superior pulmonary vein R

L

Left atrium

I

Abdominal aorta

FIG. 6.80  Coronal CT reformat of pulmonary vessels.

CHAPTER 6   Thorax

SVC

Aortic arch

S

Left pulmonary artery

Left descending pulmonary artery

L

R

Right atrium Left inferior pulmonary vein

Inferior vena cava

I

Left atrium

Abdominal aorta

Left superior pulmonary vein

FIG. 6.81  Coronal oblique CT reformat of left pulmonary vessels.

Right ascending pulmonary artery

S

Right pulmonary artery

Aortic arch

Pulmonary trunk Right descending (interlobar) pulmonary artery L

R

Right inferior pulmonary vein

Left ventricle

Left atrium

I

FIG. 6.82  Coronal oblique CT reformat of right pulmonary vessels.

359

360

CHAPTER 6   Thorax

Superior vena cava

Ascending aorta

A

Pulmonary trunk

Left pulmonary artery

Right superior pulmonary vein

L

R

Right superior lobe bronchus Right mainstem bronchus

Azygos vein

P

Descending aorta

Left mainstem bronchus

FIG. 6.83  Axial, T1-weighted MRI of chest with right superior pulmonary vein.

Right superior pulmonary vein

Ascending aorta

A

Pulmonary trunk

Left superior pulmonary vein

L

R

Right pulmonary artery

Superior vena cava

P

Descending aorta

Left pulmonary artery

FIG. 6.84  Axial CT of chest with superior pulmonary veins.

The inferior vena cava is formed by the junction of the common iliac veins in the pelvis and ascends the abdomen to the right of the abdominal aorta and anterior to the vertebral column. It passes through the caval hiatus of the diaphragm and almost immediately enters the inferior portion of the right atrium (Figs. 6.81, 6.93, and 6.94).

Obstruction of a pulmonary artery or one of its branches is known as a pulmonary embolism. This condition prevents blood flow to the alveoli and, if left in place for several hours, will result in permanent collapse of the alveoli. It is commonly caused by thrombosis from the lower extremities.

CHAPTER 6   Thorax

Right atrium

Right coronary artery

Pulmonary trunk

A

361

Aortic valve

R

L

Right inferior pulmonary vein

Left atrium

P

Left inferior pulmonary vein

Left inferior lobe bronchus

FIG. 6.85  Axial, T1-weighted MRI of chest with inferior pulmonary veins.

Right atrial appendage (auricle)

Ascending aorta A

Pulmonary trunk Left main coronary artery

Right atrium

Left anterior descending artery

Superior vena cava

Origin of circumflex artery

Right superior pulmonary vein L

R

Left atrial appendage (auricle)

Right inferior pulmonary vein

Left atrium

Decending aorta

P

FIG. 6.86  Axial CT of chest with inferior pulmonary veins.

Left inferior pulmonary vein

362

CHAPTER 6   Thorax S Apex

Groove for right subclavian artery Groove for superior vena cava

Oblique fissure Superior lobar bronchus

Groove for azygos vein

Right pulmonary artery

Anterior border Right superior pulmonary vein

Right mainstem bronchus P

A

Horizontal fissure

Groove for esophagus

Cardiac impression

Lower right pulmonary vein

Oblique fissure

Pulmonary ligament

Base of lung Groove for inferior vena cava I

FIG. 6.87  Medial surface of right lung.

Trachea Brachiocephalic trunk Left brachiocephalic vein Ascending aorta

Right pulmonary artery Left atrium Right atrium Right ventricle Diaphragm

FIG. 6.88  Sagittal, T1-weighted MRI of right mediastinum and diaphragm.

Groove for left subclavian artery

S Apex

Groove for left brachiocephalic vein Left pulmonary artery Left mainstem bronchus Superior vena cava Apex

S

Right lung Right mainstem superior lobe bronchus

Left pulmonary veins

Groove for aorta P

A

Posterior border

Cardiac impression Right pulmonary arteries

Cardiac notch

Pulmonary ligament

Lingula Inferior border Right superior pulmonary vein A

P Right atrium

I

FIG. 6.90  Medial surface of left lung.

Right inferior pulmonary vein

Right middle lobe

I

Right inferior lobe

FIG. 6.89  Sagittal CT reformat of right mediastinum and pulmonary vessels.

Left lung Aortic arch Pulmonary trunk Left mainstem bronchus Pulmonary semilunar valve

Left superior pulmonary artery

Left pulmonary vein Left ventricle

Right ventricular outflow tract Right ventricle

Left kidney

FIG. 6.91  Sagittal, T1-weighted MRI of left mediastinum.

CHAPTER 6   Thorax

364

S Left pulmonary artery

Left superior lobe of lung

Trachea

S Left superior lobe bronchus

Left superior pulmonary vein

Pulmonary trunk

Right pulmonary artery Ascending aorta

Left inferior P lobe bronchus

A

Aortic root

I

Right ventricle

Inferior vena cava

Left ventricle

I

FIG. 6.92  Sagittal CT reformat of left mediastinum and pulmonary

FIG. 6.93  Sagittal, T1-weighted MRI of inferior vena cava.

vessels.

IVC

Right ventricle

Interventricular septum A

Left ventricle

R

L

Descending aorta

P

P

Left atrium Right atrium

Left inferior lobe of lung

Left inferior pulmonary vein

A

Esophagus

FIG. 6.94  Axial CT of inferior vena cava (IVC).

CHAPTER 6   Thorax

365

axillary region, where it becomes the right axillary artery. The left common carotid artery is the second vessel to branch from the aortic arch. It arises just behind the left sternoclavicular joint and ascends into the neck along the left side of the trachea to the level of C4, where it bifurcates into the left external and internal carotid arteries (Fig. 6.26). The left subclavian artery arises from the aortic arch posterior to the left common carotid artery and arches laterally toward the axilla in a manner similar to that of the right subclavian artery, where it continues as the left axillary artery (Figs. 6.95–6.101). The common carotid arteries supply blood to the head and neck, whereas the subclavian arteries supply blood to the upper extremities. The right and left internal thoracic (internal mammary) arteries arise from the respective subclavian artery at the base of the neck. They run deep to the ribs, just lateral to the sternum, to supply blood to the anterior portion of the thorax (Figs. 5.82 and 6.97–6.100).

Circulation of Blood Through the Heart Deoxygenated blood is brought to the right atrium from the peripheral tissues of the body by the inferior and superior venae cavae. The right atrium contracts, forcing blood through the tricuspid (right atrioventricular) valve into the right ventricle. The right ventricle pumps blood through the pulmonary semilunar valve to the pulmonary arteries, which enter into the lungs for oxygen exchange. Oxygenated blood returns to the heart via the pulmonary veins, which enter the left atrium. The left atrium forces blood through the bicuspid (mitral) valve into the left ventricle, where it is then pumped through the aortic semilunar valve to the aorta and then on to the rest of the body (Fig. 6.62).

Branches of the Aortic Arch The three main branches off of the aortic arch are the brachiocephalic trunk, left common carotid artery, and left subclavian artery (Fig. 6.95). The brachiocephalic (innominate) trunk is the first major vessel and the largest branch arising from the aortic arch. It ascends obliquely to the upper border of the right sternoclavicular joint, where it divides into the right common carotid and right subclavian arteries (Figs. 6.95–6.97). The right common carotid artery ascends the neck lateral to the trachea to the level of C4, where it divides into the right external and internal carotid arteries. The right subclavian artery curves posterior to the clavicle into the

The internal thoracic artery is commonly used as a graft to bypass major coronary stenosis of the heart in a procedure called a coronary artery bypass graft (CABG). Typcially, the internal thoracic artery will be grafted to the left anterior descending artery for revascularization of the heart muscle. The internal thoracic artery also creates an important collateral pathway between the aorta and external iliac vessels in the event that the descending aorta is blocked.

Right common carotid artery S

Right internal jugular vein

Left common carotid artery Brachiocephalic trunk Left internal jugular vein

Right subclavian artery

Left subclavian artery

R L

Right subclavian vein

Left brachiocephalic vein

Right brachiocephalic vein

Aortic arch Descending aorta

Superior vena cava

Left pulmonary artery Ascending aorta I

FIG. 6.95  Anterior view of great vessels.

366

CHAPTER 6   Thorax Right common carotid artery

Right subclavian artery

S

Left common carotid artery Brachiocephalic trunk

Left subclavian artery Aortic arch Descending aorta

Ascending aorta

Left ventricle

FIG. 6.96  MRA of aorta.

I Right common carotid artery

Left vertebral artery

S

Right subclavian artery

Right internal thoracic artery

Left subclavian artery

Descending aorta Brachiocephalic trunk

FIG. 6.97  3D CT of aortic arch.

Left common carotid artery

I

Aortic arch

CHAPTER 6   Thorax Right brachiocephalic vein

Brachiocephalic trunk

A

Left brachiocephalic vein

367

Left common carotid artery

Right internal thoracic artery

R

L

Trachea

Esophagus

P

Left subclavian artery

FIG. 6.98  Axial, T1-weighted MRI of chest with branches of aortic arch and brachiocephalic veins.

Right internal thoracic artery

Brachiocephalic trunk

A

Sternum

Left brachiocephalic vein

Left pectoralis major muscle Left pectoralis minor muscle

R

L Left common carotid artery

Trachea Right brachiocephalic vein

P

Esophagus

Scapula Left subclavian artery

FIG. 6.99  Axial CT of chest with branches of aortic arch and brachiocephalic veins.

368

CHAPTER 6   Thorax Right brachiocephalic vein

Right subclavian artery

Left common carotid artery

Left clavicle

A Left brachiocephalic vein

Right internal thoracic artery and vein

L

R

P Right common carotid artery

Left subclavian artery

Left subclavian vein

FIG. 6.100  Axial CT with left subclavian vein. S

Right common carotid artery

Left common carotid artery

Right subclavian artery

Left subclavian artery

Brachiocephalic trunk

Aortic arch

Right brachiocephalic vein

Left pulmonary artery

R L

Left superior pulmonary vein

Right pulmonary artery

Right inferior pulmonary vein

Descending aorta I

FIG. 6.101  MRA of right brachiocephalic vein.

Tributaries of the Superior Vena Cava The superior vena cava receives blood from the head and neck via the internal and external jugular veins, as well as from the upper extremities via the subclavian veins (Figs. 6.95, 6.101, and 6.102). The subclavian veins are a continuation of the axillary veins and course posterior to the clavicles. They receive blood from the external jugular veins before uniting with the internal jugular

veins behind the sternoclavicular joints, where they continue as the brachiocephalic veins. The left brachiocephalic vein courses across the midline, anterior to the branches of the aorta, to unite with the right brachiocephalic vein just posterior to the costal cartilage of the right first rib (Figs. 6.60, 6.98, and 6.99). The union of the two brachiocephalic veins forms the superior vena cava, which empties into the right atrium of the heart (Figs. 6.67, 6.68, 6.95, and 6.98–6.102).

CHAPTER 6   Thorax Right internal jugular vein

S

Left internal jugular vein

Right subclavian vein Left subclavian vein Right brachiocephalic vein

Left brachiocephalic vein L

R

Ascending aorta

Superior vena cava

Pulmonary trunk

Right atrium

I

Left ventricle

FIG. 6.102  Coronal CT reformat of tributaries of the superior vena cava.

369

370

CHAPTER 6   Thorax

CORONARY CIRCULATION

Ten percent of the total cardiac volume of each heartbeat is required solely to supply blood to the heart muscle.

The cardiac muscle requires a continuous supply of oxygen and nutrients, which is supplied by coronary circulation. The coronary circulation consists of arteries that supply blood to the heart and cardiac veins that provide venous drainage. The vessels of the coronary circulation frequently vary in their development and distribution of blood to the heart.

Right common carotid artery S Right subclavian artery

Coronary Arteries The two main coronary arteries are the first vessels to branch off the ascending aorta (Figs. 6.103 and 6.104). The right coronary artery arises from the base or root of the aorta (right aortic sinus) and passes anteriorly

Left common carotid artery Left subclavian artery

Brachiocephalic trunk

Left brachiocephalic vein

Right brachiocephalic vein

Arch of aorta

Ascending aorta

Ligamentum arteriosum

Superior vena cava

Left pulmonary artery

Right pulmonary arteries

Left coronary artery R

L

Right coronary artery

Left auricle Circumflex artery

Right atrium

Left marginal artery Left anterior descending artery

Marginal branch of right coronary artery

Left ventricle Right ventricle

A

I

Posterior descending artery

Apex

Left common carotid artery S Left subclavian artery

Brachiocephalic trunk Right brachiocephalic vein Ascending aorta

Descending aorta

Superior vena cava

Left pulmonary artery Left pulmonary veins Left coronary artery

R

Left marginal artery

Aortic valve Right pulmonary veins Left atrium

Circumflex artery

Inferior vena cava

Left anterior descending artery

B

Right pulmonary arteries

L

I Posterior descending artery

Right coronary artery

FIG. 6.103  Heart with coronary vessels. (A) Anterior view. (B) Posterior view.

CHAPTER 6   Thorax Right coronary artery

Ascending aorta

A

Right ventricle

371

Left main coronary artery

Right atrial appendage Left anterior descending artery L

R

Circumflex artery

Descending aorta

Right atrium

Superior vena cava

P

Left atrium

FIG. 6.104  Axial MRA of heart with right coronary artery.

between the pulmonary trunk and right atrium to descend in the coronary groove (Figs. 6.104 and 6.105). As it reaches the diaphragmatic surface, it gives off a right marginal branch that runs toward the apex of the heart. The right coronary artery then turns to the left and enters the posterior interventricular groove, where it gives off the posterior descending artery (posterior interventricular branch). The posterior descending artery continues to descend along the posterior interventricular groove toward the apex, where it commonly anasto­ moses with the left anterior descending artery of the left coronary artery (Fig. 6.103). The right coronary artery and its branches supply the right atrium, right ventricle, interventricular septum, and the SA and AV nodes. It also supplies a portion of the left atrium and ventricle (Figs. 6.104–6.108). The left coronary artery arises from the left aortic sinus and passes to the left between the pulmonary trunk and left atrium to reach the coronary groove (Figs. 6.103 and 6.104). Soon after reaching the coronary groove, the left coronary artery divides into the circumflex and left anterior descending arteries (Figs. 6.104 and 6.105). The circumflex artery winds

around the left border of the heart to the posterior surface, where it gives off the left marginal artery that passes obliquely toward the apex of the heart. The left anterior descending artery (LAD) descends in the anterior interventricular groove toward the apex of the heart, where it reaches the diaphragmatic surface and will sometimes anastomose with the posterior descending artery. Along its course, the LAD gives off diagonal branches that supply the interventricular septum, including the AV bundles, and most of the left ventricle and atrium (Figs. 6.105–6.117).

The left anterior descending artery (LAD) is also known as the “widow maker” because many men die of blockage to this artery. The LAD can supply up to 55% of the left ventricle and is considered a key vessel for blood supply to the heart. If the artery is blocked at the beginning of its course then the rest of the vessel that supplies blood to the anterior heart wall is blocked as well. This will lead to a massive heart attack and frequently to sudden death.

CHAPTER 6   Thorax

372

Right coronary artery origin

A

Right ventricle

Aortic semilunar valve

Right aortic sinus

Left anterior descending artery L

R

Left ventricular myocardium

Right atrial appendage Superior vena cava

Circumflex artery

Right superior pulmonary vein

Great cardiac vein

Right inferior pulmonary vein

Left atrium

P

Posterior Descending aortic sinus aorta

Left inferior pulmonary vein

FIG. 6.105  Axial CT of heart with right coronary artery. Pulmonary trunk

Ascending aorta

Left circumflex artery

Left ventricle Right coronary artery Right ventricle

FIG. 6.106  MRA of heart with right coronary artery.

CHAPTER 6   Thorax

Ascending aorta

Right aortic sinus

S

Left aortic sinus

Left coronary artery

Left circumflex artery

Right coronary artery

Diagonal branch L

R Posterior aortic sinus

I

Left ventricle

Left anterior descending artery

FIG. 6.107  3D CT of aortic sinuses and coronary arteries.

Aorta

S

Pulmonary trunk

Left main coronary artery

Diagonal branch of LAD

Right coronary artery L

R

Left ventricle

Right atrium

Left anterior descending artery

Right marginal branch

I

Right ventricle

FIG. 6.108  3D CT of right coronary artery.

373

CHAPTER 6   Thorax

374

Superior vena cava

Ascending aorta

A

Pulmonary trunk

Diagonal branch of LAD

R

L Left anterior descending artery (LAD) Great cardiac vein Left circumflex artery

Left main coronary artery

Left atrium

P

Descending aorta

Marginal branch of circumflex artery

FIG. 6.109  Axial MRA of heart with left coronary artery.

Internal thoracic artery

A

Pulmonary semilunar valve

Aortic root Left main coronary artery

Right atrium L

R Right superior pulmonary vein

Left inferior pulmonary vein

Superior vena cava

Left atrium

Esophagus

P

Descending aorta

FIG. 6.110  Axial CT of heart with left coronary artery.

CHAPTER 6   Thorax Ascending aorta

S

375

Left atrium

Left main coronary artery

Pulmonary trunk

Left circumflex artery

Right ventricle

Diagonal branch of left anterior descending artery

Left anterior descending artery

Left ventricle

I

FIG. 6.111  3D CT of left coronary arteries.

Cardiac Veins Most of the venous return from the heart is carried by the coronary sinus as it runs along the posterior section of the coronary groove and terminates in the right atrium immediately to the left of the inferior vena cava (Fig. 6.118). The coronary sinus is a wide venous channel situated in the posterior part of the coronary groove and is the main vein of the heart (Figs. 6.114, 6.115, 6.118, and 6.119). Its tributaries include the great, small, and middle cardiac veins; the left posterior ventricular vein; and the oblique vein of the left atrium (Figs. 6.67 and 6.68). The great cardiac vein, the main tributary of the coronary sinus, arises near the apex of the heart and ascends in the anterior interventricular groove adjacent to the anterior interventricular artery to the base of the ventricles (Fig. 6.118). It receives blood from the left posterior ventricular vein and the left marginal vein before emptying into

the coronary sinus. The small (right) cardiac vein runs in the coronary groove between the right atrium and ventricle and joins the coronary sinus from the right side. It receives blood from the right atrium and ventricle. The middle (posterior) cardiac vein commences at the apex of the heart and ascends along the posterior interventricular groove to the base of the heart, where it drains into the coronary sinus near the drainage site of the small cardiac vein. It receives blood from the posterior surface of both ventricles. The left posterior ventricular vein carries blood from the posterior wall of the left ventricle as it runs along the diaphragmatic surface of the left ventricle to drain into either the great cardiac vein or the coronary sinus (Fig. 6.119). The small oblique vein of the left atrium descends obliquely over the posterior wall of the left atrium and enters the left end of the coronary sinus. Two small anterior cardiac veins drain directly into the right atrium (Fig. 6.118).

CHAPTER 6   Thorax

376

Right coronary artery

A

Left anterior Right descending ventricle artery Interventricular septum Left ventricle

L

R Right atrium Esophagus

P

Azygos vein

Descending aorta

FIG. 6.112  Axial, T1-weighted MRI of heart with LAD.

Right coronary artery

A

Right ventricle

Interventricular septum

Left anterior descending artery

Left ventricle L

R

Papillary muscle

Right atrium

Bicuspid valve

Left atrium

P

Descending aorta

FIG. 6.113  Axial CT of heart with LAD.

CHAPTER 6   Thorax Right coronary artery

Right ventricle

A

377

Left ventricle

R

L

P

Coronary sinus

Descending aorta

FIG. 6.114  Axial, T1-weighted MRI of heart with coronary sinus.

A Right ventricle Interventricular septum

Right coronary artery Right atrium

Left ventricle R

L Esophagus

Coronary sinus

Descending aorta

Azygos vein

P

FIG. 6.115  Axial CT of heart with coronary sinus.

378

CHAPTER 6   Thorax A Right coronary artery

Liver

L

R IVC

Diaphragm

Esophagus Descending aorta Azygos vein P

FIG. 6.116  Axial, T1-weighted MRI of heart with right coronary artery.

A Right ventricle

Left anterior descending artery

Right coronary artery

Interventricular septum R

L Left ventricle

Inferior vena cava

Descending aorta

P

FIG. 6.117  Axial CT of heart with right coronary artery.

CHAPTER 6   Thorax S

Inferior thyroid vein Left vertebral artery

Right brachiocephalic vein

Inferior thyroid vein S

Left brachiocephalic vein

Right internal thoracic vein

379

Right brachiocephalic vein

Left brachiocephalic vein

Left internal thoracic vein

Azygos vein Superior vena cava

Thymic vein Left pulmonary artery

Superior vena cava

L

Left auricle

R

Right pulmonary arteries R Right pulmonary veins

L

Right auricle

Left marginal vein

Great cardiac vein

Anterior cardiac veins

Inferior vena cava

Right atrium Right ventricle

Left ventricle

Small right cardiac vein

Great cardiac vein

Inferior vena cava

Coronary sinus Coronary groove

Apex Small right cardiac vein

A

I

Middle cardiac vein

Middle cardiac vein

B

Coronary sinus

FIG. 6.118  Heart with cardiac veins. (A) Anterior view. (B) Posterior view. Great cardiac vein

S

Left atrium Coronary sinus

Middle cardiac vein

Left posterior ventricular vein

Left ventricle

I

Left marginal vein

FIG. 6.119  3D CT of heart with coronary sinus.

CHAPTER 6   Thorax

380

OFF-AXIS CARDIAC IMAGING In an effort to standardize nomenclature for tomographic imaging of the heart, the American Heart Association (AHA) published a statement recommending that all cardiac imaging modalities use the same nomenclature for defining tomographic imaging planes. The first AHA recommendation states that “all cardiac imaging modalities should define, orient, and display the heart using the long axis of the left ventricle and selected planes oriented at 90-degree angles relative to the long axis.” The second recommendation states, “The names for the 90-degree–oriented cardiac planes used in all imaging modalities should be vertical long axis, horizontal long axis and short axis. These correspond to the short-axis, apical two-chamber, and apical four-chamber planes traditionally used in 2D echocardiography” (Fig. 6.120). We will follow these recommendations for

labeling cardiac images throughout this text. In off-axis cardiac imaging, each successive acquisition provides the landmarks for planning the next acquisition (view) and provides a logical method to obtain 90-degree viewing of the heart according to its intrinsic short and long axes. Several different methods can be used to obtain views of the cardiac planes during an examination, of which we provide an example of one method. To obtain the vertical long-axis (VLA) view, an oblique coronal image can be positioned parallel to the interventricular septum, directly through the left atrium and ventricle (Figs. 6.121–6.123). This plane closely approximates the right anterior oblique projection used in cineangiography and the two-chamber view used in echocardiography. The horizontal long-axis (HLA) view can be obtained by angling an oblique coronal image to bisect the left ventricle, bicuspid valve, and left atrium (Figs. 6.124–6.126). The HLA view demonstrates the A

Right ventricle Interventricular septum Left ventricle

Horizontal long axis Bicuspid valve Short axis

Vertical long axis

FIG. 6.120  Off-axis planes (views) of heart.

Right atrium

Descending aorta

P

Left atrium

FIG. 6.121  Axial CT of heart for planning vertical long-axis images. S Left superior pulmonary vein

Left auricle (atrial appendage)

Left ventricular myocardium

Left atrium

Coronary sinus

Bicuspid valve

Left ventricle

FIG. 6.122  Vertical long-axis CT.

I

CHAPTER 6   Thorax

381

S Pulmonary trunk Right ventricle

Left atrium

Bicuspid valve

Left ventricle

FIG. 6.123  Vertical long-axis MRI.

I Left atrium

S

Bicuspid valve

Left ventricle

FIG. 6.124  Vertical long-axis CT of heart for planning horizontal long-axis images.

I

Right ventricle

Right ventricle Interventricular septum

Interventricular septum

Left ventricle

Left anterior descending artery

Right coronary artery Right atrium

Left ventricle Left atrium

Bicuspid valve Left pulmonary vein

FIG. 6.125  Horizontal long-axis CT.

Right atrium

Left atrium

Bicuspid valve

FIG. 6.126  Horizontal long-axis MRI.

382

CHAPTER 6   Thorax

four cardiac chambers and is comparable with the fourchamber plane used in echocardiography. The short-axis (SA) view can be obtained by using the HLA image to prescribe an oblique plane through the right and left ventricles, oriented perpendicular to the interventricular septum (Figs. 6.127–6.133). The right and left ventricles both have areas called the inlet and outlet depending on the flow of blood throughout the chambers. The inlets represent the flow of blood between the atria and the ventricles, while the outlets represent the flow of blood between the ventricles and the pulmonary and systemic circulations. The inlet of the right ventricle

includes the tricuspid valve, and the outlet contains the pulmonary semilunar valve. The right ventricular outflow tract (RVOT) is used to visualize the pulmonary semilunar valve and differentiate the left ventricle from the pulmonary artery (Figs. 6.134–6.136). The inlet of the left ventricle involves the bicuspid valve, and the outlet includes the aortic semilunar valve. Typically, the left ventricular outflow tract (LVOT) defines the view that provides visualization of both bicuspid and aortic semilunar valves, as well as the left atrium, left ventricle, and ascending aorta (Figs. 6.137–6.139). (Text continues on page 388)

Right ventricle

Interventricular septum

Left anterior descending artery

Right coronary artery Right atrium

Left ventricle

Left atrium Bicuspid valve

FIG. 6.127  Horizontal long-axis CT of heart for planning short-axis images.

LAD

Papillary muscle

Left ventricle

Interventricular septum Right ventricle

Great cardiac vein

FIG. 6.128  Short-axis CT with ventricles.

CHAPTER 6   Thorax Great cardiac vein

LAD

Bicuspid valve

Pulmonary trunk Left atrium

Right ventricular outflow track

Coronary sinus Right ventricle

Descending aorta

Right atrium

FIG. 6.129  Short-axis CT with pulmonary trunk.

S

Pulmonary trunk

Ascending aorta

Aortic semilunar valve

Left atrium

Right coronary artery

Right atrium

I

FIG. 6.130  Short-axis CT with left atrium.

383

384

CHAPTER 6   Thorax

Interventricular septum

Papillary muscle

Right ventricle

Left ventricle

Myocardium

FIG. 6.131  Short-axis MRI with ventricles.

S

Pulmonary trunk LAD A

P

Right ventricle

Left ventricle

Right atrium

Coronary sinus

Descending aorta

I

FIG. 6.132  Short-axis MRI with pulmonary trunk.

CHAPTER 6   Thorax Sternum

A

Right lung Pulmonary trunk

Ascending aorta R

L Left lung

Liver

Left atrium Descending aorta

Vertebral body P

FIG. 6.133  Short-axis MRI with left atrium.

A

Ascending aorta

SVC

Pulmonary trunk R

L

Right pulmonary artery Descending aorta Esophagus

P

FIG. 6.134  Axial CT of pulmonary trunk for planning RVOT images.

385

386

CHAPTER 6   Thorax S

Pulmonary trunk

Aortic root

Pulmonary vein

RVOT

Right ventricle

Left ventricle

I

FIG. 6.135  CT of right ventricular outflow tract (RVOT).

S

Left pulmonary artery

Pulmonary trunk

Left mainstem bronchus

Root of aorta A

P Left pulmonary veins

Right ventricle

Left atrium

Liver

I

FIG. 6.136  MRI of right ventricular outflow tract (RVOT).

CHAPTER 6   Thorax Left coronary artery

Ascending aorta S SVC

Aortic semilunar valve

Right atrium

Left ventricle

R

L

IVC Right coronary artery

I

FIG. 6.137  Coronal CT of heart for planning LVOT images.

Aortic semilunar valve

Left atrium

Ascending aorta

Pulmonary trunk

Pulmonary semilunar valve

Right ventricle

Left ventricular outflow tract

Coronary sinus Bicuspid valve Aorta

Left ventricle

FIG. 6.138  CT of left ventricular outflow

tract.

387

388

CHAPTER 6   Thorax Ascending aorta

Pulmonary trunk Left atrium Left ventricular outflow tract Bicuspid valve Right ventricle

Descending aorta

Left ventricle

FIG. 6.139  MRI of left ventricular outflow tract.

AZYGOS VENOUS SYSTEM The azygos venous system, which provides collateral circulation between the inferior and superior venae cavae, can be divided into the azygos and hemiazygos veins (Fig. 6.140). Together, they drain blood from most of the posterior thoracic wall and from the bronchi, pericardium, and esophagus. The larger azygos vein ascends along the right side of the vertebral column, whereas the hemiazygos vein ascends along the left side. The hemiazygos vein crosses the vertebrae to the right behind the aorta to join the azygos vein at approximately T7–T9. The azygos vein then arches over the hilum of the right lung to empty into the posterior surface of the superior vena cava (Figs. 6.35 and 6.140–6.144).

Superior vena cava

S

Left superior intercostal vein

Azygos vein

Posterior intercostal veins Accessory hemiazygos vein Posterior intercostal veins

Posterior intercostal veins

Hemiazygos vein

R

L Left renal vein

Inferior vena cava

Ascending lumbar vein Lumbar veins

I

FIG. 6.140  Anterior view of azygos venous system.

CHAPTER 6   Thorax S

Azygos arch Azygos vein

R

L

Hemiazygos vein Thoracic vertebra

I

FIG. 6.141  Coronal CT reformat of azygos vein.

S

Superior vena cava Azygos arch Right mainstem bronchus

A

P

Right atrium

I

FIG. 6.142  Sagittal CT reformat of azygos arch.

389

390

CHAPTER 6   Thorax

A

L

R

Liver

IVC

Azygos vein

P

Hemiazygos vein

Descending aorta

FIG. 6.143  Axial, T1-weighted MRI of abdomen with azygos and hemiazygos veins.

A

L

R

Esophagus

Azygos vein

P

Hemiazygos vein

Descending aorta

FIG. 6.144  Axial CT of chest with azygos and hemiazygos veins.

Spleen

CHAPTER 6   Thorax TABLE 6.5

391

Muscles Associated with Respiration

Muscle

Origin

Insertion

Action

Intercostal

Inferior border of ribs

Superior border of ribs below

Serratus posterior superior Serratus posterior inferior Levatores costarum Diaphragm

Spinous processes and supraspinous ligaments of C7–T2 Spinous processes and supraspinous ligaments of T11–L2 Transverse processes of C7 and T1–T11 Xiphoid process, costal margin, fascia over the quadratus lumborum, and psoas major muscles; vertebral bodies L1–L3

Posterior aspect of 2nd–5th ribs

Fixes intercostal spaces during respiration and aids forced inspiration by elevating ribs Assists forced inspiration

Posterior aspect of 9th–12th ribs

Assists in forced expiration

Rib between tubercle and angle Central tendon of the diaphragm

Elevate the ribs Pushes the abdominal viscera inferiorly, increasing the volume of the thoracic cavity for inspiration

MUSCLES Muscles Associated with Respiration Muscles associated with respiration are the intercostal, serratus posterior superior, serratus posterior inferior, levatores costarum, and diaphragm (Table 6.5). The intercostal spaces of the ribs are filled with three layers of intercostal muscles (external, internal, and innermost layer) (Figs. 6.145–6.147). These muscles act together to elevate the ribs and expand the thoracic cavity, as well as keep the intercostal spaces somewhat rigid. The serratus posterior superior muscle spans from C7–T2 to ribs 2–5 and acts to assist forced inspiration, whereas the serratus posterior inferior muscle spans from T11– L2 to ribs 9–12 and acts to assist forced expiration Anterior membranous portion of external intercostal muscles removed

(Figs. 6.148–6.150). The levatores costarum muscles arise from the transverse processes of C7 and T1–T11. They extend obliquely to insert on the rib below, between the tubercle and angle (Fig. 6.148). The levatores costarum muscles act to elevate the ribs. The diaphragm is a large dome-shaped muscle that spans the entire thoracic outlet and separates the thoracic cavity from the abdominal cavity (Figs. 6.151 and 6.152). It is the chief muscle of inspiration because it enlarges the thoracic cavity vertically as the domes move inferiorly and flatten. The muscle fibers of the diaphragm converge to be inserted into a central tendon, which is situated near the center of the diaphragm immediately below the pericardium, with which it is partially blended. The diaphragm

Anterior membranous portion of external intercostal muscles

Rib 1

S

External intercostal membrane A

Transversus thoracis muscle

2 3 4 5

R

L

Internal intercostal muscle

R

Intercostales intimi muscle (innermost layer)

6 7 8 9 External intercostal 10 muscles

External intercostal muscles Muscle fibers of external intercostal muscles in region of vertebral column (posteriorly)

I

FIG. 6.145  Anterior view of intercostal muscles.

External intercostal muscle Internal intercostal membrane

P

FIG. 6.146  Axial view of intercostal muscles.

L

392

CHAPTER 6   Thorax

Carina

A

Pectoralis major muscle

Pectoralis minor muscle

Serratus anterior muscle

R

L

Trachea in Rhomboid muscle

Intercostal muscle

P

FIG. 6.147  Axial CT of chest at level of carina with thoracic muscles.

Levatores costarum

S

Serratus posterior superior

Serratus posterior inferior

I

FIG. 6.148  Posterior view of chest with posterior serratus muscles. is attached to the lumbar spine via two tendinous structures termed crura (Figs. 6.151 and 6.153–6.155). The right crus arises from the anterior surfaces of L1–L3, whereas the left crus arises from the corresponding parts of L1–L2 only. The left and right crura join together across the ventral aspect of the abdominal aorta to form the medial arcuate ligament. Three major openings, or hiatuses,

of the diaphragm allow for the passage of vessels and organs from the thorax to the abdomen. The aortic hiatus allows for the passage of the descending aorta, azygos vein, and thoracic duct. The caval hiatus allows for the passage of the inferior vena cava and the right phrenic nerve. The esophageal hiatus allows for the passage of the esophagus and the vagus nerve (Figs. 6.151 and 6.152).

CHAPTER 6   Thorax

A

Trapezius muscle

P

Serratus posterior superior muscle

Splenius capitis muscle

Erector spinae muscles

Transversospinal muscles

FIG. 6.149  Axial CT of chest with serratus posterior superior muscle.

A Sternum

Serratus anterior muscle

Descending aorta

R

L

IVC

Serratus posterior inferior muscle

Latissimus dorsi muscle

Rib

Esophagus

P

Erector spinae muscle

Trapezius muscle

FIG. 6.150  Axial, T1-weighted MRI of chest with serratus posterior inferior muscle.

393

394

CHAPTER 6   Thorax

Inferior vena cava in caval hiatus

Central tendon S

Esophagus in esophageal hiatus

R

L

Diaphragm

Aorta in aortic hiatus Right crus

Left crus

I

FIG. 6.151  Inferior view of diaphragm.

S Left brachiocephalic vein

Right brachiocephalic vein

Aortic arch Pulmonary trunk

SVC

Serratus anterior muscle

Right atrium R

L Left ventricle

IVC

Diaphragm

Caval hiatus

I

FIG. 6.152  Coronal CT reformat of serratus anterior muscle.

CHAPTER 6   Thorax

395

S

Aorta Thoracic vertebra

R

L Intercostal muscle

Latissimus dorsi muscle

Diaphragm Crus of diaphragm

Liver

Spleen

I

FIG. 6.153  Coronal CT reformat of diaphragm.

Inferior vena cava

A

Descending aorta

Right crus

Left crus Lumbar vertebra L

R

P

FIG. 6.154  Axial, T1-weighted MRI of abdomen with crura.

396

CHAPTER 6   Thorax

Right crus

Inferior vena cava

Descending aorta

A

L

R

Intercostal muscle

P

Left crus

R FIG. 6.155  Axial CT of chest with crura.

Muscles of the Anterior and Lateral Thoracic Walls Muscles of the anterior and lateral thoracic region are the pectoralis major, pectoralis minor, subclavius, and serratus anterior. Muscles associated with the movement of the upper extremity, such as the pectoralis, subclavius, and serratus anterior, can also function as accessory muscles for respiration (Fig. 6.156 and Table 6.6). For example, the pectoralis muscles (major and minor), located on the anterior surface of the chest, primarily aid in the movement of the upper limb, but the pectoralis major muscle can also act to expand the thoracic cavity on deep inspiration (Figs. 6.147 and 6.156). The subclavius, a small, triangular-shaped muscle located between

L

the clavicle and first rib, acts alone to stabilize the clavicle and depress the shoulder (Fig. 6.5). Conjointly with the pectoralis muscles, the subclavius muscles act to raise the ribs, drawing them upward and expanding the chest, thus becoming important agents in forced inspiration. Additionally, the serratus anterior muscles aid in respiration. The serratus (meaning “sawlike”) anterior muscle is visualized on the lateral border of the thorax. It extends from the medial border of the scapula to the lateral surface of the first through eighth ribs. The primary action of the serratus anterior muscle is to laterally rotate and protract the scapula. It can, however, assist in raising the ribs for inspiration (Figs. 6.152 and 6.156; see also Chapter 9, muscles and tendons). Sternocleidomastoid muscle

S Scalene muscles

Infrahyoid muscles

Deltoid muscle

Trapezius muscle

Pectoralis minor muscle

R

L

Pectoralis major muscle

FIG. 6.156  Anterior view of muscles associ-

ated with the thorax.

Serratus anterior muscle

Latissimus dorsi muscle I

CHAPTER 6   Thorax TABLE 6.6

397

Muscles of the Anterior and Lateral Thoracic Walls.

Muscle

Origin

Insertion

Action

Pectoralis major

Bicipital groove of humerus and deltoid tuberosity

Flexes, adducts, and medially rotates arm; acts as accessory for inspiration

Pectoralis minor

Clavicular head—medial half of clavicle Sternal head—lateral manubrium and sternum, six upper costal cartilages Anterior surface of 3rd–5th ribs

Coracoid process of the scapula

Subclavius

First rib and cartilage

Inferior surface of the clavicle

Serratus anterior

Angles of superior 8th or 9th ribs

Medial border of scapula

Elevates ribs of scapula, protracts scapula, and assists serratus anterior Depresses the shoulder and assists pectoralis in inspiration Laterally rotates and protracts scapula

BREAST

S

The female breast, or mammary gland, lies within the subcutaneous tissue overlying the pectoralis major muscle. Typically, the breast extends laterally from the sternum to the axilla and inferiorly from the second to the seventh ribs. For examination purposes, the breast can be divided into four quadrants (upper inner, upper outer, lower outer, lower inner) and the tail of Spence (Fig. 6.157). The breast consists of three layers of tissue: subcutaneous layer, mammary layer, and retromammary layer (Fig. 6.158). The subcutaneous layer contains the skin and all of the subcutaneous fat. The mammary layer consists of glandular tissue, excretory (lactiferous) ducts, and connective tissues. The glandular tissue consists of 15 to 20 lobes arranged radially around a centrally located nipple. The glandular lobes are embedded in connective tissue and fat, which give the breast its size and shape. Excretory (lactiferous) ducts extend from each

Clavicle Pectoralis minor muscle Intercostal muscle Fascia of pectoral muscles Pectoralis major muscle Alveolus Ductule Duct Lactiferous duct Lactiferous sinus Nipple pores

P Mammary layer (glandular tissue)

Subcutaneous layer Adipose tissue Suspensory ligaments (Cooper’s ligaments)

S

Retromammary layer

A

I

FIG. 6.158  Sagittal view of female breast.

R

Tail of Spence Upper inner

Upper outer L

Lower inner

Lower outer

I

FIG. 6.157  Anterior view of left breast.

lobe to the nipple, where they terminate as small openings. Cords of connective tissue coursing throughout the mammary layer, from the dermis to the thoracic fascia, are known as the suspensory ligaments of the breast, or Cooper’s ligaments. These ligaments provide support for the breasts. The retromammary layer contains muscle, deep connective tissue, and retromammary fat (Figs. 6.159 and 6.160). Axillary lymph nodes drain the lymphatics from the breast, arm, and walls of the thorax. They are frequently clustered around the axillary vessels, the borders of the pectoralis muscles, and the posterior margin of the axilla.

398

CHAPTER 6   Thorax S

A

P

Pectoralis major muscle Retromammary layer

Mammary layer

FIG. 6.159  Sagittal, T1-weighted MRI of female breast.

Nipple

Glandular

I

Subcutaneous layer

Retromammary layer

Subcutaneous layer

FIG. 6.160  Axial, T1-weighted MRI of female breast.

REFERENCES Anderson, M. W., & Fox, M. G. (2017). Sectional anatomy by MRI and CT (4th ed.). Philadelphia: Elsevier. Applegate, E. (2009). The sectional anatomy learning system (3rd ed.). Philadelphia: Saunders. Boxt, L. M., & Abbara, S. (2016). The requisites: Cardiac imaging (4th ed.). Philadelphia: Elsevier. Cerqueira, M. D., Weissman, N. J., & Dilsizian, V., et al. (2002). Standardized myocardial segmentation and nomenclature for tomographic imaging of the heart: A statement for healthcare professionals from the Cardiac Imaging Committee of the Council on Clinical Cardiology of the American Heart Association. Circulation, 105, 539. El-Sherief, A. H., Lau, C. T., & Wu, C. C., et al. (2014). International Association for the Study of Lung Cancer (IASLC) lymph node map: Radiologic review with CT illustration. Radiographics, 34(6), 1680–1691.

Mammary layer

Glandular layer

Frank, G. (2012). Merrill’s atlas of radiographic positions and radiologic procedures (12th ed.). St. Louis: Mosby. Haaga, J. R., & Boll, D. T. (2017). CT and MRI of the whole body (6th ed.). Philadelphia: Elsevier. Larsen, W. J. (2002). Anatomy: Development, function, clinical correlations. Philadelphia: Saunders. Manning, W. J., & Pennel, D. J. (2010). Cardiovascular magnetic resonance (2nd ed.). Philadelphia: Saunders. Palastanga, N. (2002). Anatomy and human movement: Structure and function (4th ed.). Boston: Butterworth-Heinemann. Seidel, H. M., Ball, J. W., & Dains, J. E., et al. (2010). Mosby’s guide to physical examination (7th ed.). St. Louis: Mosby. Standring, S. (2012). Gray’s anatomy, the anatomical basis of clinical practice (41st ed.). New York: Elsevier. Weir, J., & Abrahams, P. H. (2011). Imaging atlas of human anatomy (4th ed.). London: Elsevier.

CHAPTER

7

Abdomen A man’s liver is his carburetor. Anonymous

FIG. 7.1  Coronal CT reformat of abdomen with large heterogeneous left renal mass (white arrow).

The abdominal cavity houses many structures that have a large array of functions. It is for this reason that cross-sectional imaging of the abdomen is so essential in visualizing these various organs and body systems (Fig. 7.1).

OBJECTIVES • List the structures of the abdominal cavity, and differentiate among those that are contained within the peritoneum and those that are contained within the retroperitoneum. • Describe the peritoneal and retroperitoneal spaces. • Describe the lobes, segments, and vasculature of the liver. • Define the structures of the biliary system. • State the functions and location of the pancreas and spleen. • Identify the structures of the urinary system.

• List and identify the structures of the stomach and intestines. • Identify the branches of the abdominal aorta and the structures they supply. • Identify the tributaries of the inferior vena cava and the structures they drain. • List the muscles of the abdomen, and describe their functions. • List the vessels that form the portal vein, and describe the flow of blood through the portal hepatic system.

OUTLINE ABDOMINAL CAVITY, 400 Peritoneum, 400 Peritoneal Spaces, 408 Retroperitoneum, 412 Retroperitoneal Spaces, 412 LIVER, 414 Surface Anatomy, 415 Segmental Anatomy, 418 Portal Hepatic System, 424 Vasculature, 428 GALLBLADDER AND BILIARY SYSTEM, 433

PANCREAS, 439 SPLEEN, 443 ADRENAL GLANDS, 444 URINARY SYSTEM, 448 STOMACH, 455 INTESTINES, 460 ABDOMINAL AORTA AND BRANCHES, 471 Paired Branches, 473 Unpaired Branches, 477 INFERIOR VENA CAVA AND TRIBUTARIES, 488

Copyright © 2019, Elsevier Inc.

Inferior Phrenic Veins, 488 Lumbar Veins, 488 Gonadal Veins, 490 Renal Veins, 490 Suprarenal Veins, 491 Hepatic Veins, 491 LYMPH NODES, 491 MUSCLES OF THE ABDOMINAL WALL, 492

399

CHAPTER 7  Abdomen

400

ABDOMINAL CAVITY

Peritoneum

The abdominal cavity is the region located between the diaphragm and sacral promontory (Fig. 7.2). Together, the abdominal and pelvic cavities are commonly divided into four quadrants or nine distinct regions (see Chapter 1). Contents of the abdominal cavity include the liver, gallbladder and biliary system, pancreas, spleen, adrenal glands, kidneys, ureters, stomach, intestines, and vascular structures.

The walls of the abdominal cavity are lined by a thin serous membrane called the peritoneum. This membrane is divided into two layers: the parietal peritoneum, which lines the abdominal walls, and the visceral peritoneum, which covers the organs (Fig. 7.3). The two layers of peritoneum are separated by a thin film of serous fluid for lubrication that allows organs to move against each other without friction. The peritoneum forms a cavity that encloses the following organs of the abdomen: liver (except for the bare area), gallbladder, spleen, stomach, ovaries, and majority of intestines (Figs. 7.4 and 7.5). In males, the peritoneal cavity is a closed cavity, but in females, it communicates with the exterior through the uterine tubes, uterus, and vagina (Fig. 7.6A and B). The peritoneal cavity includes the greater sac and lesser sac (omental bursae). The greater sac is located between the inner surface of the anterior abdominal wall and the outer surface of the abdominal viscera. It is bounded by the parietal and visceral peritoneum, and it communicates with the lesser sac through the epiploic foramen (of Winslow) (Fig. 7.3). The lesser sac is located primarily between the posterior surface of the stomach and the posterior abdominal wall (Figs. 7.3 and 7.7–7.9). Numerous folds of peritoneum extend between organs, serving to hold them in position and at the same time enclose the vessels and nerves proceeding to each structure. These folds or double layers of peritoneum are termed mesentery, omenta, and peritoneal ligaments. The mesentery is a double layer of peritoneum that encloses the intestine and attaches it to the abdominal wall. The mesentery serves as a route for blood vessels, lymphatics, and nerves to reach the small intestine. An omentum is a mesentery or double layer of peritoneum that is attached to the stomach. The normal omentum is

S

Diaphragm

A

P

Abdominal cavity Sacral promontory

Pelvis Pubic symphysis

I

FIG. 7.2  Sagittal view of the abdominal cavity.

Parietal peritoneum

Falciform ligament A

Lesser omentum Greater sac

Liver Hepatic artery

Stomach Aorta

Bile duct

Lesser sac

Portal vein R

L

Epiploic foramen

Gastrosplenic ligament

Inferior vena cava

Spleen

Visceral peritoneum Retroperitoneum

Lienorenal ligament P

Left kidney

FIG. 7.3  Axial view of abdomen with greater and lesser sacs and peritoneal ligaments.

CHAPTER 7  Abdomen

Aorta

Retroperitoneum posterior to dotted line

A

R

L Spleen

Liver

Peritoneum

Inferior vena cava

P

Pancreas

Left Stomach kidney

FIG. 7.4  Axial, T1-weighted MRI of peritoneal and retroperitoneal structures (separated by dotted line).

Portal vein

Stomach

A

Pancreas

R

L

Spleen Liver

Peritoneum

Inferior vena cava

P

Aorta

Left Retroperitoneum kidney posterior to dotted line

FIG. 7.5  Axial CT of peritoneal and retroperitoneal structures (separated by dotted line).

401

402

CHAPTER 7  Abdomen S

S

R

L

R

L

I

I

FIG. 7.6  Anterior view of peritoneum. (A) Male peritoneum. (B) Female peritoneum.

Diaphragm

Bare area of liver

S

Coronary ligaments

Liver

Aorta

Area of epiploic foramen and lesser omentum

Lesser sac

Stomach

Pancreas

Greater sac Duodenum

Transverse colon

P

A

Mesentery

Greater omentum Parietal peritoneum

Uterus

Small intestine Rectum

Peritoneal cavity Urinary bladder

I

FIG. 7.7  Sagittal view of peritoneum and peritoneal cavity.

CHAPTER 7  Abdomen Anterior left subphrenic space

Liver

S

403

Lesser sac

Aorta

Pancreas

Superior mesenteric artery Stomach A

P

Greater sac

I

FIG. 7.8  Sagittal CT reformat of abdomen with greater and lesser sacs.

Duodenum

Liver

Lesser sac

A

Greater sac

Stomach

Anterior subphrenic space

Pancreas Superior mesenteric artery

Gallbladder

R

L

Right subhepatic space

P IVC

Aorta

Kidney

FIG. 7.9  Axial CT of abdomen with greater and lesser sacs.

404

CHAPTER 7  Abdomen

usually imperceptible on routine scans, visible only when fluid is present (Figs. 7.7 and 7.10). The greater omentum is a fat-laden fold of peritoneum that drapes down from the greater curvature of the stomach and connects the stomach with the spleen and transverse colon, whereas the lesser omentum attaches the duodenum and lesser curvature of the stomach to the liver (Figs. 7.10–7.13). Numerous peritoneal ligaments serve to connect an organ with another organ or abdominal wall. These peritoneal ligaments are not ligaments in the classic sense but are distinct regions of mesentery connecting the structures for which they are named. Three regions of the greater omentum that are characterized as peritoneal ligaments are the gastrocolic, gastrosplenic, and gastrophrenic. These ligaments attach the greater omentum to the transverse colon, hilum of the spleen, greater curvature and fundus of the stomach, diaphragm, and esophagus (Figs. 7.3, 7.11, and 7.12). Ligaments of the lesser omentum include the hepatogastric and hepatoduodenal, which serve to connect the stomach and duodenum to the liver (Fig. 7.10). Ligaments associated specifically with the liver are the round ligament

(ligamentum teres), falciform ligament, and coronary ligaments. The round ligament is a remnant of the left umbilical vein of the fetus and runs within the free inferior margin of the falciform ligament to the umbilicus. The falciform ligament extends from the liver to the anterior abdominal wall and diaphragm, forming a plane that divides the liver anatomically into right and left lobes. The falciform ligament provides the structural support that attaches the upper surfaces of the liver to the diaphragm and upper abdominal wall (Figs. 7.14 and 7.15). The coronary ligaments surround the superior pole of the liver and attach the liver to the diaphragm, forming the margins of the bare area (Figs. 7.7 and 7.16). Additional peritoneal ligaments are described in Table 7.1.

Inflammation of the peritoneum or peritoneal cavity is termed peritonitis. Acute peritonitis is most commonly caused by the leakage of infection through a perforation in the bowel.

Hepatoduodenal ligament

Lesser omentum

Hepatogastric ligament

S

Stomach Epiploic foramen Gallbladder Duodenum

L Greater omentum R

Cecum Appendix Right ovary

Sigmoid colon Right uterine tube

Rectum

I Uterus

FIG. 7.10  Anterior view of mesentery and peritoneal ligaments.

CHAPTER 7  Abdomen Greater omentum

A

Stomach

Liver

Gastrosplenic ligament R

L

Spleen

IVC

Aorta

P

Splenic vein

Hilum of spleen

FIG. 7.11  Axial, T1-weighted MRI of abdomen with greater omentum and gastrosplenic ligament.

Pancreas

A

R

Gastrosplenic Greater ligament omentum Spleen

L

P

FIG. 7.12  Axial CT of abdomen with blood accumulation demonstrating the greater omentum and gastrosplenic ligament.

405

406

CHAPTER 7  Abdomen Anterior left subphrenic space

Liver

S

Triangular ligaments

Lesser sac

Spleen

Stomach Pancreas

Mesocolon Greater omentum A

P

F I

FIG. 7.13  Sagittal CT reformat of abdomen with greater omentum and peritoneal spaces.

Falciform ligament

A

Left lobe of liver

Fissure for ligamentum venosum

Stomach

R

L

Spleen

Right lobe of liver

IVC

P

Caudate lobe of liver

FIG. 7.14  Axial, T1-weighted MRI of abdomen with falciform ligament.

CHAPTER 7  Abdomen Falciform ligament

407

Left lobe of liver

A

Fissure for ligamentum venosum

Stomach R

L Spleen

Right lobe of liver

P

Caudate lobe of liver

FIG. 7.15  Axial CT of abdomen with falciform ligament.

Coronary ligaments

Superior recess of lesser sac

S

Aorta

Stomach

IVC Right subhepatic space

Phrenicocolic ligament R

L

Paracolic gutter Mesentery of small bowel

I

Psoas muscles

FIG. 7.16  Coronal CT reformat of liver and coronary ligaments.

408

TABLE 7.1

CHAPTER 7  Abdomen Peritoneal Ligaments

Ligaments

Location

Gastrocolic ligament Gastrosplenic ligament (gastrolienal ligament) Splenorenal (lienorenal) ligament Gastrophrenic ligament

Apron portion of the greater omentum attached to the transverse colon Left portion of the greater omentum that connects the hilum of the spleen to the greater curvature and fundus of the stomach Connects the spleen and kidney Superior portion of greater omentum attached to the diaphragm and posterior aspect of the fundus and esophagus Connects the liver and kidney Connects the liver and esophagus Connects the liver to the lesser curvature of the stomach Connects the superior region of the duodenum to the liver Extends from the liver to the anterior abdominal wall and diaphragm Remnant of the fetal umbilical vein, lying in the free edge of the falciform ligament Reflections of the peritoneum that surround the bare area of the liver Where the layers of the coronary ligament meet to the left and right, respectively Attaches the left flexure of the colon to the diaphragm

Hepatorenal ligament Hepatoesophageal ligament Hepatogastric ligament Hepatoduodenal ligament Falciform ligament Round ligament (ligamentum teres) Coronary ligaments Triangular (left and right) Phrenocolic ligament

Peritoneal Spaces The peritoneal cavity contains potential spaces resulting from folds of peritoneum that extend from the viscera to the abdominal wall. These spaces can be divided into the supracolic and infracolic compartments (Fig. 7.17). The supracolic compartment is located above the transverse colon and contains the right and left subphrenic spaces and right and left subhepatic spaces. The subphrenic spaces are located between the diaphragm and the anterior portion of the liver. They are divided into right and left compartments by the falciform ligament (Figs. 7.18 and 7.19). The subhepatic spaces are located posterior and inferior between the liver and the abdominal viscera. The right subhepatic space, located between the liver

and kidney, contains Morison’s pouch, which is the deepest point of the abdominal cavity in a supine patient and a common site for collection of fluid (Figs. 7.20 and 7.21). Below the transverse colon is the infracolic compartment, which consists of the right and left infracolic spaces and the paracolic gutters. The right and left infracolic spaces are divided by the mesentery of the small intestine. The right and left paracolic gutters are troughlike spaces located lateral to the ascending and descending colon (Figs. 7.17 and 7.22 and Table 7.2). The deeper right gutter is a common site for free fluid collection. The paracolic gutters communicate with the spaces of the pelvis.

S

Supracolic compartment

Diaphragm Left subphrenic space

Right subphrenic space

Liver Falciform ligament Stomach Left subhepatic space

Right subhepatic space

R

L Right infracolic space

Infracolic compartment

Transverse colon Left infracolic space Small intestine Descending colon

Right paracolic gutter

Left paracolic gutter Ascending colon

I

FIG. 7.17  Anterior view of peritoneal spaces.

CHAPTER 7  Abdomen Falciform ligament

Lesser omentum

A

Right subphrenic space

Left subphrenic space Lesser sac Stomach L

R

Spleen

Pancreas

P Kidney

FIG. 7.18  Axial view of subphrenic spaces.

Right subphrenic space

Liver

A

Stomach

Left subphrenic space

R

L

Bare area of liver

P

FIG. 7.19  Axial CT of abdomen with subphrenic spaces.

Spleen

409

410

CHAPTER 7  Abdomen Falciform ligament A

Left subhepatic space Stomach Left subphrenic space

Right subhepatic space

Lesser sac L

R Liver

Spleen

Morison’s pouch

P Right kidney

Pancreas

Left kidney

FIG. 7.20  Axial view of subhepatic spaces and Morison’s pouch.

Right subphrenic space

Liver

Left subhepatic space A

Left kidney

Anterior renal (Gerota’s) fascia

R

L

Morison’s pouch

Right subhepatic space

P

FIG. 7.21  Axial CT of abdomen with subhepatic spaces and Morison’s pouch.

CHAPTER 7  Abdomen Right paracolic gutter

Right infracolic space

A

Left infracolic space

Left paracolic gutter

R

L

Ascending colon

P

FIG. 7.22  Axial CT of abdomen with paracolic gutters.

TABLE 7.2

Peritoneal and Retroperitoneal Spaces

Space Peritoneal Spaces Supracolic Compartment Subphrenic Spaces Right and Left Subhepatic Spaces Right Left Infracolic Compartment Infracolic Spaces Right and Left Paracolic Gutters Right Left Retroperitoneal Spaces Pararenal Spaces Anterior Posterior Perirenal Space Right and Left

Location Above transverse colon Between diaphragm and anterior liver Right and left spaces divided by falciform ligament Posterior and inferior to liver Between right lobe of liver and kidney; contains Morison’s pouch Between left lobe of liver and kidney; includes lesser omentum Below transverse colon Divided by mesentery of small intestine Between ascending colon and right abdominal wall Between descending colon and left abdominal wall

Between anterior renal (Gerota’s) fascia and posterior surface of peritoneum Between posterior renal (Gerota’s) fascia and muscles of posterior abdominal wall Around kidney and adrenal glands; completely enclosed by renal (Gerota’s) fascia

411

412

CHAPTER 7  Abdomen (Fig. 7.23). The anterior pararenal space is located between the anterior surface of the renal fascia (Gerota’s fascia) and the posterior peritoneum. It contains the retroperitoneal portions of the ascending and descending colon, the pancreas, and the duodenum. The posterior pararenal space is located between the posterior renal fascia and the muscles of the posterior abdominal wall. There are no solid organs located in this space, just fat and vessels (Figs. 7.24 and 7.25). The left and right perirenal spaces are the areas located directly around the kidneys and are completely enclosed by renal fascia. The perirenal spaces contain the kidneys, adrenal glands, lymph nodes, blood vessels, and perirenal fat. The perirenal fat separates the adrenal glands from the kidneys and provides cushioning for the kidney (Fig. 7.26 and Table 7.2).

Retroperitoneum Structures located posterior to the peritoneum, yet lined by it anteriorly, are considered to be in the retroperitoneum and include abdominal and pelvic structures, such as the kidneys, ureters, adrenal glands, pancreas, duodenum, aorta, inferior vena cava, bladder, uterus, and prostate gland. In addition, the ascending and descending colon and most of the duodenum are situated in the retroperitoneum (Figs. 7.3–7.5).

Retroperitoneal Spaces The retroperitoneum can be divided into compartments or spaces that include the anterior and posterior pararenal spaces and left and right perirenal spaces

Pancreas

Stomach

A

Liver

Aorta

IVC

Spleen

Anterior R pararenal space

L Descending colon

Posterior pararenal space

Anterior renal (Gerota’s) fascia

P

Left kidney Perirenal Posterior renal space (Gerota’s) fascia FIG. 7.23  Axial view of retroperitoneal spaces.

Right kidney

IVC

Aorta

A

Anterior pararenal space

Left kidney R

L

Perirenal space

Posterior pararenal space

P

Renal (Gerota’s) fascia

FIG. 7.24  Axial, T1-weighted MRI of abdomen with kidneys and pararenal spaces.

CHAPTER 7  Abdomen Anterior pararenal space

IVC

A

Aorta

Left kidney

R

L Perirenal space

Right kidney

P

Renal (Gerota’s) fascia

FIG. 7.25  Axial CT of abdomen with kidneys and pararenal spaces.

Right adrenal gland

413

S

Stomach

Liver Spleen

R

L

Right perirenal space

Left perirenal space

Renal (Gerota’s) fascia

Posterior pararenal space

I

Psoas muscle

FIG. 7.26  Coronal, T2-weighted MRI of perirenal spaces.

Posterior pararenal space

414

CHAPTER 7  Abdomen flexure of the colon; and the posterior surface is bordered by the right kidney (Figs. 7.28 and 7.29). The liver is surrounded by a strong connective tissue capsule (Glisson’s capsule) that gives shape and stability to the soft hepatic tissue. It is also entirely covered by peritoneum except for the gallbladder fossa, the surface apposed to the inferior vena cava (IVC), and the bare area, which is the liver surface between the superior and inferior coronary ligaments. The liver is attached to the diaphragm via the right and left triangular ligaments, which are extensions of the coronary ligaments (Figs. 7.7, 7.16, and 7.28).

LIVER The liver is a large, complex organ with numerous functions, which include metabolic and hematologic regulation and bile production. It is the largest organ of the abdomen, occupying a major portion of the right hypochondriac and epigastric regions, sometimes extending into the left hypochondriac and umbilical regions. The liver is bordered superiorly, laterally, and anteriorly by the right hemidiaphragm (Fig. 7.27). The medial surface is bordered by the stomach, duodenum, and transverse colon; the inferior surface is bordered by the hepatic

Coronary ligament

Diaphragm S

Left triangular ligament

Right triangular ligament

R

Left lobe L

Right lobe

Falciform ligament Costal surface

Round ligament (ligament teres)

I Gallbladder

Inferior margin

FIG. 7.27  Anterior view of liver.

Falciform ligament Caudate lobe Left triangular ligament

Inferior vena cava Coronary ligaments

S

Bare area Gastric impression Right lobe Left lobe

R

L

Right triangular ligament

Attachment of the lesser omentum

Common hepatic duct Hepatic artery

Renal impression

Round ligament (ligamentum teres) Porta hepatis

Portal vein Medial left lobe

I

Colic impression Gallbladder

FIG. 7.28  Posterior view of liver.

CHAPTER 7  Abdomen Diaphragm

415

Esophagus S

Falciform ligament

Liver, left lobe Spleen

Liver, right lobe

Stomach Duodenum

Hepatic flexure

Pancreas Transverse colon

Gallbladder Ascending colon

R

L Small intestine

Ileum

Descending colon

Appendex

Urinary bladder

I

FIG. 7.29  Anterior view of abdominal viscera.

Surface Anatomy

which is located on the inferior and posterior liver surface, sandwiched between the IVC and the ligamentum venosum. The ligamentum venosum is a fibrous remnant of the ductus venosum of the fetal circulation. The quadrate lobe is located on the anteroinferior surface of the left lobe between the gallbladder and the round ligament. The hilum of the liver, the porta hepatis, is located on the inferomedial border of the liver. It is the central location for vessels to enter and exit the liver (Figs. 7.27–7.34).

The liver can be divided into lobes according to surface anatomy or into segments according to vascular supply. The four lobes commonly used for reference based on surface anatomy are the left, right, caudate, and quadrate. The left lobe is the most anterior of the liver lobes, extending across the midline. The right lobe is the largest of the four lobes and is separated from the left lobe by the interlobar fissure. The smallest lobe is the caudate lobe,

Fissure for ligamentum teres A

Left lobe of liver

Interlobar fissure

Portal vein L R Transverse fissure

IVC P

Fissure for ligamentum venosum Caudate lobe of liver

Right lobe of liver

FIG. 7.30  Axial view of liver with fissures.

416

CHAPTER 7  Abdomen Falciform ligament

Left lobe of liver

A

Fissure for ligamentum venosum

Stomach

Portal vein R

L

IVC Spleen

Right lobe of liver

Caudate lobe

P

Aorta

FIG. 7.31  Axial, T1-weighted MRI of abdomen with lobes of liver.

Falciform ligament

A

Left lobe of liver

Fissure for ligamentum venosum

Stomach

Portal vein R

L

IVC

Spleen

Right lobe of liver

P

Aorta

FIG. 7.32  Axial CT of abdomen with lobes of liver.

Caudate lobe

CHAPTER 7  Abdomen

A

Stomach

417

Caudate lobe of liver

Portal vein R

L

IVC

Spleen

P

Right lobe of liver

FIG. 7.33  Axial, T1-weighted MRI of liver with caudate lobe.

Within the liver there are several main grooves or fissures that are useful in defining the lobes and bound­ aries of the hepatic segments. The fissure for the round ligament divides the left hepatic lobe into medial and lateral segments. The fissure for the ligamentum venosum separates the caudate lobe from the left lobe, and

Quadrate lobe of liver

the transverse fissure (portal) contains the horizontal portions of the right and left portal veins. The interlobar fissure (main lobar fissure), an imaginary line drawn through the gallbladder fossa and the middle hepatic vein to the IVC, divides the right from the left lobes of the liver (Fig. 7.30).

A

Gallbladder

R

L

Right lobe of liver

IVC

P

FIG. 7.34  Axial CT of liver with quadrate lobe.

418

CHAPTER 7  Abdomen liver into right and left lobes. The right lobe is divided into anterior and posterior sections by the right hepatic vein, and the left lobe is divided into medial and lateral sections by the left hepatic vein. Each section is then subdivided transversely by the right and left portal veins, creating eight segments. Each segment can be considered functionally independent; each has its own branch of the hepatic artery, portal vein, and bile duct and is drained by a branch of the hepatic veins (Figs. 7.36–7.49).

Segmental Anatomy Current practice favors the division of the liver into eight segments, according to its vascular supply, which can aid in surgical resection. According to the French anatomist Couinaud, the liver can be divided into segments based on the branching of the portal and hepatic veins. The three main hepatic veins divide the liver longitudinally into four sections (Fig. 7.35). The middle hepatic vein divides the

(Text continues on page 424)

S

Right lobe

Left lobe

Inferior vena cava

Left hepatic vein

Right hepatic vein

Middle hepatic vein IVa

VIII

II I

Right portal vein

Left portal vein

VII III

R IVb

V

L

Falciform and round ligaments

VI

Hepatic artery I

Common bile duct Portal vein

Gallbladder

Inferior vena cava

FIG. 7.35  Anterior view of segmentation of liver.

CHAPTER 7  Abdomen Left portal vein

Hepatic veins

I

VIII

Body of pancreas

S

Stomach

II

IV

III

Right portal vein

Spleen

VII

Superior mesenteric vein

V

Gallbladder Portal vein

Superior mesenteric artery

VI L

R

Head of pancreas

I

FIG. 7.36  Coronal CT reformat of liver segments and portal vein.

IVC

S

Gastroesophageal junction

Stomach

Tail of pancreas

VIII

Spleen VII Aorta

V Right hepatic vein R

L

Ascending colon

Kidney

I

FIG. 7.37  Coronal CT reformat of liver segments.

419

420

CHAPTER 7  Abdomen Left hepatic vein A Median arcuate ligament of diaphragm

Middle hepatic vein IVa

II

Stomach

VIII R

L Spleen

Right hepatic vein

VII Left lung

Inferior vena cava

FIG. 7.38  Axial view of liver segments.

Aorta

P A

III IV Middle hepatic vein

II R

L

I

VIII Right hepatic vein VII

P

IVC

FIG. 7.39  Axial, T1-weighted MRI of liver segments. Medial segment of left lobe

Left hepatic vein

Lateral segment of left lobe

A

Right ventricle

Middle hepatic vein Anterior segment of right lobe

Left ventricle

III

IV

II

R Right hepatic vein

L VIII VII

Posterior segment of right lobe

FIG. 7.40  Axial CT of liver segments.

P

IVC

CHAPTER 7  Abdomen Left portal vein A Middle hepatic vein Right hepatic vein

Stomach

IVa

III II

VIII

Tail of pancreas

I

R

L

Right portal vein

VII

Spleen

Inferior vena cava P Right adrenal gland

Aorta

FIG. 7.41  Axial view of liver segments. Left hepatic vein

A III IV

II

Middle hepatic vein R

Ligamentum venosum L

I VIII

Anterior branches of right portal vein

VII

P

IVC

FIG. 7.42  Axial, T1-weighted MRI of liver segments.

A

III

Left portal vein

Stomach

II

IV

R Anterior branches of right portal vein

Caudate lobe

L VIII Spleen VII

Right portal vein P

FIG. 7.43  Axial CT of liver segments.

421

422

CHAPTER 7  Abdomen Middle hepatic vein

Portal vein

IVb

Right hepatic vein

Falciform ligament A

III

Stomach

V

L Pancreas

R Inferior vena cava

VI

Spleen Aorta

Right kidney

FIG. 7.44  Axial view of liver segments.

P Falciform ligament

A

Ligamentum venosum

III Proximal left portal vein

IV

I R

L VIII

Right portal vein

VII

Posterior branches of right portal vein

P

IVC

FIG. 7.45  Axial, T1-weighted MRI of liver segments. Falciform ligament Medial segment of left lobe

A

Caudate lobe

IV

R

L

V VI

Posterior branches of right portal vein IVC

Lateral segment of left lobe

III

Anterior branches of right portal vein Anterior segment of right lobe

Main portal vein

Posterior segment of right lobe

P

FIG. 7.46  Axial CT of liver segments.

CHAPTER 7  Abdomen A

Superior mesenteric vein

Head of pancreas IVb

Gallbladder

III Superior mesenteric artery

V VI R

L

Duodenum

Left kidney

Inferior vena cava

P

Aorta

FIG. 7.47  Axial view of liver segments. Falciform ligament

A III Portal vein

IV

Posterior branch of right portal vein

I R

L V

VI

Posterior branch of right portal vein

P

IVC

FIG. 7.48  Axial, T1-weighted MRI of liver segments. Lateral segment of left lobe

Falciform ligament Medial segment of left lobe Anterior segment of left lobe

III IV

IVC V

Posterior segment of left lobe

Portal vein

VI

FIG. 7.49  Axial CT of liver segments.

423

424

CHAPTER 7  Abdomen to the caudate lobe (segment I) and then divides into anterior and posterior branches that subdivide into superior and inferior branches to supply the right lobe of the liver (segments V, VI, VII and VIII). The left main portal vein initially courses to the left, then turns medially toward the ligamentum teres. It branches to supply the lateral segments (segments II and III) of the left lobe and the superior and inferior sections of segment IV (Figs. 7.35 and 7.41–7.49).

Portal Hepatic System The liver receives nutrient-rich blood from the gastrointestinal tract via the portal hepatic system (Figs. 7.35, 7.36, and 7.50). The major vessel of this system is the portal vein, which is formed in the retroperitoneum by the union of the superior mesenteric and splenic veins, posterior to the neck of the pancreas at the portal splenic confluence (Figs. 7.50–7.55). It passes obliquely to the right, posterior to the hepatic artery within the lesser omentum, and enters the liver at the porta hepatis (Figs. 7.28, 7.56, and 7.57). At the porta hepatis, the portal vein branches into right and left main portal veins that then follow the course of the right and left hepatic arteries. The right main portal vein first sends branches

Portal hypertension is caused by obstruction of blood flow in the portal hepatic system. This condition can lead to splenomegaly and ascites. The most common cause of portal hypertension is cirrhosis of the liver.

S Right hepatic vein

Inferior vena cava (IVC)

Middle hepatic vein

Left hepatic vein Spleen

Liver Left main portal vein Right main portal vein

Splenic vein L

R

Portal splenic confluence

Inferior mesenteric vein

Portal vein Superior mesenteric vein

Descending colon

Ascending colon Rectum

Ileum

FIG. 7.50  Anterior view of portal hepatic system.

I Right hepatic vein

Left main portal IVC vein

S

Middle hepatic vein

Splenic vein

Right main portal vein Portal vein R

L

Portal splenic confluence Superior mesenteric vein

FIG. 7.51  CT MIP of portal vein.

I

CHAPTER 7  Abdomen

IVC

Portal vein

425

Neck of pancreas Aorta

A

Stomach

Splenic vein R

L Spleen

Liver

P

Pancreas

FIG. 7.52  Axial, T1-weighted MRI of liver and portal vein.

Gallbladder

Body of pancreas

A

Portal vein Splenic vein R

L

Spleen

Liver

IVC

P

FIG. 7.53  Axial CT of liver and portal vein.

Aorta

426

CHAPTER 7  Abdomen Superior mesenteric vein

A

Splenic vein

R

L

Head of pancreas

P

IVC

FIG. 7.54  Axial, T1-weighted MRI of abdomen with portal and splenic veins.

A

Neck of pancreas

Portal splenic confluence

Head of pancreas

R

L

IVC

P

Portal vein

FIG. 7.55  Axial CT of abdomen with portal and splenic veins.

Splenic vein

CHAPTER 7  Abdomen

427

Left ventricle

S Right atrium

Left lobe of liver

IVC

Right hepatic vein R

L

Right lobe of liver

Portal vein

Gastric vein

I

Spleen

Right Right lobe hepatic Right main of liver vein portal vein

FIG. 7.56  Coronal MR venogram of portal hepatic system.

S

IVC

Left lobe of liver

Portal vein

Portal splenic confluence Splenic vein

R

L

Ileal branches of superior mesenteric vein

I Jejunal Superior mesenteric branches vein of superior mesenteric vein

FIG. 7.57  Coronal CT

reformat of portal hepatic system.

428

CHAPTER 7  Abdomen entering the porta hepatis, the proper hepatic artery divides into right and left hepatic arteries, which continue to branch and supply the lobes of the liver. The right hepatic artery is larger than the left and supplies the majority of the right lobe of the liver. It passes posterior to the uncinate process of the pancreas and runs along the posterior wall of the common bile duct into the right hepatic lobe. The left hepatic artery approaches the liver in the lesser omentum and branches to supply the caudate, quadrate, and medial and lateral segments of the left lobe of the liver (Fig. 7.62).

Vasculature The liver is unusual in that it has a dual blood supply, receiving arterial blood (20%–25%) from the common hepatic artery and nutrient-rich venous blood (75%– 80%) from the portal vein. The common hepatic artery usually arises as one of three branches off the celiac trunk, coursing to the right to enter the lesser omentum anterior to the portal vein (Figs. 7.58–7.61). It branches into the proper hepatic and gastroduodenal arteries just above the duodenum. While within or just before

Left gastric artery

S

Aorta Splenic artery

Stomach

Left hepatic artery Right hepatic artery Proper hepatic artery Celiac trunk

Spleen

R

Right gastric artery

L

Common hepatic artery Left gastroepiploic artery

Gastroduodenal artery Doudenum Pancreas Right gastroepiploic artery

I

FIG. 7.58  Anterior view of celiac trunk and hepatic artery. Portal vein Common hepatic duct

Left hepatic artery S

Caudate lobe, anterior surface Right crus of diaphragm

Liver, right lobe

Right hepatic artery

Left gastric artery L Inferior vena cava

Cystic duct R

Common hepatic artery

Cystic artery

Proper hepatic artery Right gastric artery Gastroduodenal artery Gallbladder fundus

Duodenum

I

Superior pancreaticoduodenal artery

Common bile duct

FIG. 7.59  Anterior view of hepatic artery, CBD, and portal vein.

CHAPTER 7  Abdomen

429

A

Portal vein R

L

IVC

Common hepatic artery

Celiac trunk

P

Aorta

Splenic artery

FIG. 7.60  Axial, T1-weighted MRI of abdomen with celiac trunk and hepatic artery. Right hepatic artery

A

IVC R

L

Common hepatic artery

P

Celiac trunk

FIG. 7.61  Axial CT of abdomen with celiac trunk and hepatic artery. The venous drainage of the liver occurs via the small interlobar and intersegmental hepatic vessels that merge into the three major hepatic veins, emptying directly into the IVC, just below the diaphragm (Figs. 7.50 and 7.63). The right hepatic vein, the largest, lies between the right anterior and posterior hepatic segments; drains segments V, VI, and VII; and enters the IVC at the right lateral aspect. The middle hepatic vein lies in the interlobar fissure; drains segments IV, V, and VIII; and then enters the IVC at the anterior or right anterior surface. The smallest hepatic vein, the left hepatic vein, courses between

the medial and lateral segments of the left lobe, drains segments II and III, then enters the left anterior surface of the IVC (Figs. 7.35–7.49, 7.64, and 7.65). Segment I drains directly into the IVC through smaller hepatic veins. Frequently, the middle and left hepatic veins converge to form a common trunk before emptying into the IVC just below the diaphragm. The IVC lies in a groove along the posterior wall of the liver and ascends into the thoracic cavity through the caval hiatus of the diaphragm and enters the right atrium of the heart (Figs. 7.64–7.67).

430

CHAPTER 7  Abdomen Right hepatic artery

Left hepatic artery

Celiac trunk S

Left gastric artery

Aorta

Proper hepatic artery

R

L

Gastroduodenal artery

Common hepatic artery

I

Splenic artery

FIG. 7.62  CTA of celiac trunk and hepatic artery.

Superior anterior segment, right lobe S Right hepatic vein

IVC Middle hepatic vein Caudate lobe

Superior posterior segment, right lobe VIII

Left hepatic Superior lateral segment, vein left lobe

I

II

VII L

R IV III VI

Inferior posterior segment, right lobe

Inferior lateral segment, left lobe

V

I Inferior anterior segment, right lobe

Medial segment, left lobe

FIG. 7.63  Couinaud segmentation of the liver with hepatic veins.

CHAPTER 7  Abdomen Left hepatic vein

A

Middle hepatic vein

Stomach Aorta R

L Spleen

P

Right hepatic vein

IVC

FIG. 7.64  Axial, T1-weighted MRI of abdomen with hepatic veins.

Middle hepatic vein

A

Left hepatic vein

Diaphragm

R

L

Esophagus

Right hepatic vein

IVC

P

Aorta

FIG. 7.65  Axial CT of liver with hepatic veins.

431

CHAPTER 7  Abdomen

432

Left ventricle

S Right atrium IVC

Left lobe of liver Right hepatic vein R

L

Right lobe of liver

Spleen

Portal vein

I

Gastric vein

FIG. 7.66  MRV with hepatic and portal veins.

IVC

Esophagus S

Heart

Esophageal hiatus

Caval hiatus

Ribs

Right hepatic vein

Stomach Spleen

Right lobe of liver R

L

I

FIG. 7.67  Coronal CT reformat of right hepatic vein and IVC.

CHAPTER 7  Abdomen

433

gallbladder fossa on the anteroinferior portion of the right lobe of the liver, closely associated with the interlobar fissure. It functions as the reservoir for storing and concentrating bile before it is transported to the duodenum. The gallbladder can be divided into a fundus, body, and neck (Figs. 7.69–7.74). The fundus is the rounded distal portion of the gallbladder sac that is

GALLBLADDER AND BILIARY SYSTEM The biliary system is composed of the gallbladder and bile ducts (both intrahepatic and extrahepatic), which serve to drain the liver of bile and store it until it is transported to the duodenum to aid in digestion (Fig. 7.68). The hollow, pear-shaped gallbladder is located in the S

Inferior vena cava

Hepatic veins

Liver R Right hepatic duct

L

Left hepatic duct

Cystic duct

Hepatic artery

Common hepatic duct

Pancreatic duct Portal vein

Gallbladder

Duodenum

Common bile duct Sphincter of Oddi

I

FIG. 7.68  Anterior view of intrahepatic biliary system.

Fundus of gallbladder Body of gallbladder Neck of gallbladder

S Right hepatic duct

Left hepatic duct Common hepatic duct Gallbladder

Common bile duct

Cystic duct

L

Pancreatic duct

Tail

R Neck Body

Pancreas

Ampulla of Vater Duodenum Head

I

FIG. 7.69  Anterior view of extrahepatic biliary system.

434

CHAPTER 7  Abdomen

Neck of gallbladder

Right hepatic duct

Spiral valves of Heister S

Left hepatic duct

Hartmann’s pouch

Common hepatic duct

Body of gallbladder

Fundus of gallbladder

Cystic duct Common bile duct R

L

2nd portion of duodenum

Pancreatic duct

Ampulla of Vator Sphincter of Oddi

I

FIG. 7.70  Gallbladder and biliary system.

Intrahepatic ducts

S

Stomach

R

L

Gallbladder

Common hepatic duct

Cystic duct

I

Duodenum Common bile duct

Pancreatic duct

FIG. 7.71  MR cholangiopancreatogram (MRCP) of biliary system.

CHAPTER 7  Abdomen

435

S Diaphragm

Liver Common hepatic duct

Anterior abdominal wall P

A

Cystic duct Pancreas

Common bile duct

Gallbladder

Duodenum Transverse colon I

FIG. 7.72  Sagittal view of liver and gallbladder.

S

Portal vein

Liver

A

P Kidney

Gallbladder

I

FIG. 7.73  Sagittal, T2-weighted MRI of liver and gallbladder. frequently in contact with the anterior abdominal wall. The widest portion, the body, gently tapers superiorly into the neck. The narrow neck lies to the right of the porta hepatis and continues as the cystic duct. The neck contains circular muscles that create spiral folds within the mucosa called the spiral valves of Heister (Fig. 7.70). These valves are particularly prominent at the bend formed by the neck and cystic duct, a common area for gallbladder impaction during acute or chronic cholecystitis. The gallbladder has a muscular wall that contracts when stimulated by the hormone cholecystokinin forcing bile through the extrahepatic biliary system into the duodenum. Cholecystokinin is secreted by cells in the

duodenum as a response to ingestion of fat and protein into the stomach or duodenum. Bile is an alkaline fluid formed within the liver and stored in the gallbladder to be discharged into the duodenum for assistance in the digestion and absorption of fats and elimination of cholesterol and bilirubin from the body. It is collected for transport to the gallbladder by the intrahepatic bile ducts. The intrahepatic bile ducts run beside the hepatic arteries and portal veins throughout the liver parenchyma. The intrahepatic ducts merge into successively larger ducts as they follow a course from the periphery to the central portion of the liver, eventually forming the right and left hepatic ducts (Figs. 7.68–7.71). The right and left hepatic ducts unite

436

CHAPTER 7  Abdomen Portal Right vein lobe of liver

S

A

P

Gallbladder

Transverse colon

I

Right kidney

FIG. 7.74  Sagittal CT reformat of liver and gallbladder. at the porta hepatis to form the proximal portion of the common hepatic duct (CHD), which marks the beginning of the extrahepatic biliary system (Fig. 7.69). The CHD is located anterior to the portal vein and lateral to the hepatic artery in its caudal descent from the porta hepatis. As the CHD descends in the free border of the lesser omentum, it is joined from the right by the cystic duct to form the common bile duct (CBD). The CBD continues a caudal descent along with the hepatic artery and portal vein within the hepatoduodenal ligament (Fig. 7.68). It

Gastroduodenal artery

curves slightly to the right, away from the portal vein, then courses posterior and medial to the first part of the duodenum behind the head of the pancreas (Figs. 7.71, 7.72, and 7.75–7.79). The CBD follows a groove on the posterior surface of the pancreatic head, then pierces the medial wall of the second part of the duodenum along with the main pancreatic duct (duct of Wirsung) through the ampulla of Vater (Fig. 7.69). The ends of both ducts are surrounded by the circular muscle fibers of the sphincter of Oddi (Fig. 7.70).

Common bile duct

Superior mesenteric vein

Splenic vein

A

Superior mesenteric artery R

L

Head of pancreas

Inferior vena cava

P

Aorta

FIG. 7.75  Axial, T1-weighted MRI of abdomen and CBD.

CHAPTER 7  Abdomen Portal vein

Diaphragm

S

Stomach

Spleen

Common bile duct R

Jejunum L

Ascending colon

Body of pancreas

Duodenum

I

Ileum

Head of pancreas

FIG. 7.76  Coronal, T2-weighted MRI of abdomen and CBD.

Left hepatic duct

Portal vein

A

Common hepatic artery

Splenic artery

Right hepatic duct L

R

Tail of pancreas Spleen

Right kidney

IVC

P

Aorta

Celiac trunk

FIG. 7.77  Axial CT of abdomen with hepatic ducts.

437

CHAPTER 7  Abdomen

438

Gallbladder

A

Portal vein

SMA

R

Splenic vein

L

Common hepatic duct

Spleen

P IVC

Aorta

FIG. 7.78  Axial CT of abdomen with common hepatic duct.

Gastrodoudenal artery

Head of pancreas

A

Superior mesenteric vein

Gallbladder

Duodenum R

L

Common bile duct IVC

Superior mesenteric artery

P

Aorta

Spleen

FIG. 7.79  Axial CT of abdomen with CBD.

CHAPTER 7  Abdomen

The pancreas has both an endocrine (insulin, glucagon) and exocrine (digestive enzymes) function. It delivers its endocrine hormones into the draining venous system and its enzymes into the small intestines. The endocrine hormones help control plasma glucose concentration. Insulin’s chief role is to regulate cellular absorption and utilization of glucose, thereby affecting carbohydrate, protein, and lipid metabolism in body tissues. Glucagon, acting in opposition to insulin, tends to raise plasma sugar levels by increasing the rate of glycogen breakdown and glucose synthesis in the liver. Pancreatic digestive enzymes include amylase for the digestion of starch, lip­ ase for the digestion of lipids, peptidases for protein digestion, and sodium bicarbonate to neutralize gastric acid. The pancreatic enzymes are carried to the duodenum via a system of pancreatic ducts. The main pancreatic duct (duct of Wirsung) begins in the tail and runs the length of the gland to the ampulla of Vater, where it empties, together with the CBD, into the duodenum through the sphincter of Oddi (Figs. 7.69–7.71 and 7.86). The arterial supply of the pancreas comes from branches of the celiac and superior mesenteric arteries. Venous blood drains from the pancreas into the portal vein via the superior mesenteric or splenic vein. The pancreas is unencapsulated and has a distinct lobulated appearance, making identification easy in cross-section.

PANCREAS The pancreas is a long, narrow retroperitoneal organ that lies posterior to the stomach and extends transversely at an oblique angle between the duodenum and splenic hilum. The pancreas can be divided into the head, uncinate process, neck, body, and tail (Fig. 7.80). The broad, flat head of the pancreas lies inferior and to the right of the body and tail, nestled in the curve of the second portion of the duodenum at approximately the level of L2–L3. The head is anterior to the IVC and renal veins (Figs. 7.80 and 7.81). Two vessels can be commonly seen running through the head: the CBD in the right posterior aspect and the gastroduodenal artery in the anterior aspect (Figs. 7.79, 7.80, 7.82, and 7.83). The uncinate process is a medial and posterior extension of the head, lying between the superior mesenteric vein and IVC (Figs. 7.80–7.83). The neck, the constricted portion of the gland, is located between the pancreatic head and body. Located just posterior to the neck is the portal splenic confluence, where the portal vein is formed by the merging of the superior mesenteric and splenic veins (Figs. 7.51, 7.55, 7.57, and 7.80). The body is the largest and most anterior portion of the pancreas, extending transversely to the left, anterior to the aorta and superior mesenteric artery (Figs. 7.84 and 7.85). The splenic vein runs along the posterior surface of the body on its route to the portal splenic confluence. The body tapers superiorly and posteriorly into the pancreatic tail. The tail extends into the left anterior pararenal space, anterior to the left kidney, to end at the splenic hilum (Figs. 7.80 and 7.84–7.86).

Acute pancreatitis can lead to the leakage of powerful digestive enzymes. Pancreatic necrosis results when the enzymes “digest” the surrounding tissue.

Aorta Inferior vena cava Right hepatic artery

Celiac axis Splenic artery S and vein

Main portal vein

Body

Common hepatic artery Proper hepatic artery R Gastroduodenal artery

Spleen L Tail

Posterior superior pancreaticoduodenal artery

Great pancreatic artery Dorsal pancreatic artery

Duodenum

Neck

Head

Uncinate process

Anterior superior pancreaticoduodenal artery Anterior interior I pancreaticoduodenal artery Inferior vena cava

439

Superior mesenteric artery and vein

Aorta

FIG. 7.80  Anterior view of pancreas and adjacent structures.

CHAPTER 7  Abdomen

440

Liver

Right atrium

S

IVC Stomach Head of pancreas

Uncinate process of pancreas

Superior mesenteric vein

Duodenum A

P

Loops of small bowel

I

FIG. 7.81  Sagittal CT reformat of pancreas and IVC.

Gastroduodenal artery

Common bile duct

A

Superior mesenteric vein

Gallbladder Superior mesenteric artery R

L

Duodenum

Left renal vein

Head of pancreas

Right renal IVC vein

P

Uncinate process of pancreas

FIG. 7.82  Axial, T1-weighted MRI of abdomen with head of pancreas and duodenum.

CHAPTER 7  Abdomen

Liver

Gastroduodenal artery

441

Stomach

A

Superior mesenteric vein Superior mesenteric artery R

L

Gallbladder

Duodenum

Head of pancreas

IVC

P

Common bile duct

Spleen

FIG. 7.83  Axial CT of abdomen with head of pancreas and duodenum.

A

Stomach

R

L

Spleen

Body of pancreas

IVC

P

FIG. 7.84  Axial, T1-weighted MRI of pancreas.

Aorta

Left kidney

Tail of pancreas

442

CHAPTER 7  Abdomen Superior mesenteric artery

Pancreatic duct

A

Body of pancreas Right renal vein Left renal vein

R

L Tail of pancreas

Right kidney

IVC

Neck of pancreas

P

Aorta

Left kidney

Spleen

FIG. 7.85  Axial CT of pancreas and pancreatic duct.

Liver

Head of pancreas

Portal vein

Body of pancreas

S

Pancreatic duct

Pancreatic tail

R

Spleen

L

Gallbladder

Duodenum

Ampulla of Vater

I

Uncinate process of pancreas

FIG. 7.86  Coronal CT curved-reformat of pancreatic duct.

CHAPTER 7  Abdomen

the spleen is in contact with the diaphragm, pleura, left lung, and ribs. The spleen is attached to the greater curvature of the stomach and the left kidney by the gastrosplenic and lienorenal ligaments, respectively (Fig. 7.87). The spleen receives its arterial blood from the splenic artery and is drained via the splenic vein. The splenic artery and vein enter and exit the spleen at the splenic hilum between the gastric and renal depressions (Figs. 7.80, 7.88, and 7.89). The spleen is a highly vascular organ that functions to produce white blood cells, filter abnormal blood cells from the blood, store iron from red blood cells (RBC), and initiate the immune response. Normal splenic parenchyma is homogeneous; however, immediately after intravenous contrast injection, the spleen can have a heterogeneous appearance on early arterial phase images (Fig. 7.89).

SPLEEN The spleen, the largest lymph organ in the body, is composed of vascular and lymphoid tissue. The cellular components of the spleen create a highly vascular, spongy parenchyma called red and white pulp. The red pulp contains large quantities of blood, and the white pulp contains lymphoid tissue and white blood cells. The spleen is an intraperitoneal organ that is covered entirely by peritoneum except at its small bare area at the splenic hilum. It is located posterior to the stomach in the left upper quadrant of the abdomen, protected by the 9th through 11th ribs (Figs. 7.37 and 7.87–7.89). The spleen is bordered on its medial side by the left kidney, splenic flexure of the colon, and pancreatic tail. The posterior border of

Falciform ligament

Lesser omentum A

Greater sac Stomach

Liver

Lesser sac Hepatic artery

Gastrosplenic ligament

R Bile duct

L

Spleen

Portal vein

Lienorenal ligament Left kidney P

FIG. 7.87  Axial view of the abdomen with greater and lesser sac, falciform, gastrosplenic, and lienorenal ligaments.

Stomach

A

R

L

Spleen

IVC

443

Left kidney

P

Splenic vein

FIG. 7.88  Axial, T1-weighted MRI of spleen.

Hilum of spleen

CHAPTER 7  Abdomen

444

Falciform ligament

Stomach

A

Pancreas Left adrenal gland Hilum of spleen R

L Red pulp of spleen

White pulp of spleen IVC

Right adrenal gland

P

Aorta

Left kidney

Splenic artery

FIG. 7.89  Axial CT of spleen, early arterial phase demonstrating heterogeneous contrast enhancement.

ADRENAL GLANDS The paired adrenal (suprarenal) glands are retroperitoneal structures located superior to each kidney (Figs. 7.90 and 7.91). They are separated from the superior surface of the kidneys by perirenal fat and are enclosed, along with the kidneys, by renal fascia (Gerota’s fascia) (Figs. 7.26 and 7.92). The right adrenal gland is located just posterior to the IVC, medial to the posterior segment of the right hepatic lobe, and lateral to the right crus of the diaphragm. It is generally lower and more medial than the left adrenal gland and commonly appears as an inverted V in cross-section (Figs. 7.93–7.95). The

left adrenal gland lies anteromedial to the upper pole of the left kidney. It is located in a triangle formed by the aorta, pancreatic tail, and left kidney (Fig. 7.96). It commonly appears as a triangular or Y-shaped configuration (Figs. 7.97 and 7.98). The posterior surfaces of both the right and left glands border the crus of the diaphragm. Each adrenal gland has an outer cortex and an inner medulla, which function independently (Fig. 7.90). The adrenal cortex produces more than two dozen ster­ oids, collectively called adrenocortical steroids or just corticosteroids. The corticosteroids are broken into three main categories: glucocorticoids, which affect glucose

Superior suprarenal artery

Adrenal gland Cortex

Middle suprarenal artery

S

Celiac trunk

Renal artery

Inferior suprarenal artery

Kidney Adrenal gland

Superior mesenteric artery Inferior vena cava

FIG. 7.90  Anterior view of adrenal glands.

I Aorta

Renal vein

Medulla

CHAPTER 7  Abdomen

445

FIG. 7.91  Axial view with common configurations of adrenal glands.

Right adrenal gland

S

Left adrenal gland

Stomach

Spleen

Liver

L

R

Perirenal fat

Left kidney

Right kidney

Right crus of diaphragm

Right psoas muscle

I

Left crus

FIG. 7.92  Coronal, T2-weighted MRI with adrenal glands.

metabolism; mineralocorticoids, which regulate sodium and potassium levels; and androgens and estrogens, which are responsible for promoting normal development of bone and reproductive organs. The adrenal medulla produces the hormones epinephrine and norepinephrine, which accelerate metabolism and increase energy and are responsible for the body’s “fight-or-flight”

response. The adrenal glands receive arterial blood from the superior, middle, and inferior suprarenal arteries. The drainage of the right gland is via a short suprarenal vein that empties directly into the IVC. The left gland is drained by the left suprarenal vein, which empties into the left renal vein. See abdominal aorta and branches and IVC and tributaries at the end of this chapter.

446

CHAPTER 7  Abdomen

IVC

Right adrenal gland Right crus of diaphragm

Liver

Right kidney

FIG. 7.93  Axial view of right adrenal gland. Stomach

A

Pancreas

R

L Left crus of diaphragm

IVC

Spleen

Right adrenal gland

P

Right crus of diaphragm

Aorta

FIG. 7.94  Axial, T1-weighted MRI of right adrenal gland. Stomach

A

R

L Left adrenal gland

IVC

Aorta

Right adrenal gland

P

Right crus of diaphragm

FIG. 7.95  Axial CT of right adrenal gland.

Left kidney

CHAPTER 7  Abdomen A Pancreas Left adrenal gland

Aorta

Pancreatic tail R L

Splenic vein Left crus of diaphragm Left kidney

FIG. 7.96  Axial view of left adrenal gland.

P

Aorta

A

Stomach

Portal vein

Tail of pancreas R

L

IVC Right adrenal gland

Right crus of diaphragm

Left crus of diaphragm

P

Left adrenal gland

Left kidney

FIG. 7.97  Axial, T1-weighted MRI of left adrenal gland. Falciform ligament

Left lobe of liver

A

Hepatic artery

Celiac trunk

Aorta IVC Stomach

Right adrenal gland

Left adrenal gland R

L Perirenal fat

Right kidney

Left kidney

Right crus Vertebra of diaphragm

P

FIG. 7.98  Axial CT of left adrenal gland.

Left crus of diaphragm

447

448

CHAPTER 7  Abdomen pyramids of the medulla. The cortex contains the functional subunit of the kidney, the nephron, which consists of the glomerulus and convoluted tubules and is responsible for filtration of urine (Fig. 7.104). The renal medulla consists of segments called renal pyramids that radiate from the renal sinus, the fat-filled cavity surrounding the renal pelvis, to the outer surface of the kidney (Figs. 7.101 and 7.104). The striated-appearing pyramids contain the loops of Henle and collecting tubules and function as the beginning of the collecting system. Arising from the renal papilla are the cup-shaped minor calyces (Fig. 7.104). Each kidney has 7 to 14 minor calyces that merge into 2 or 3 major calyces. The major calyces join to form the renal pelvis, which is the largest dilated portion of the collecting system and is continuous with the ureters (Fig. 7.104). Surrounding the kidneys and perirenal fat is another protective layer called the renal fascia (Gerota’s fascia). The renal fascia functions to anchor the kidneys to surrounding structures in an attempt to prevent bumps and jolts to the body from injuring the kidneys. In addition, the renal fascia acts as a barrier, limiting the spread of infection that may arise from the kidneys (Fig. 7.101). The medial indentation in the kidney is called the hilum; it allows the renal artery and vein and ureters to enter and exit the kidney (Figs. 7.90, 7.99, and 7.105–7.108).

URINARY SYSTEM The structures of the urinary system include the kidneys, ureters, bladder, and urethra. Those that are located within the abdomen are the kidneys and ureters (Fig. 7.99). The bladder and urethra are located in the pelvis and are discussed in Chapter 8. The kidneys are retroperitoneal bean-shaped organs that lie against the posterior abdominal wall on either side of the vertebral column (Figs. 7.98–7.100). They lie at an oblique orientation, with the upper poles more medial and posterior than the lower poles. They are located on each side of the spine between T12 and L4 and are embedded in perirenal fat (Figs. 7.99–7.101). The right kidney is usually slightly lower due to displacement by the liver (Figs. 7.99, 7.102, and 7.103). The kidneys function to excrete waste (end products of metabolism) from the blood, form urine, and balance body fluids. The kidneys also have endocrine functions that include production and release of erythropoietin, which stimulates the bones to make red blood cells; renin, which aids in regulating blood pressure; and the active form of vitamin D, which helps maintain calcium absorption and mineral metabolism. Each kidney is composed of an outer cortex and an inner medulla. The renal cortex comprises the outer one-third of the renal tissue and has extensions between the renal Right renal vein

Left renal vein

S

Upper pole of left kidney Hilum

Liver

Left kidney

Right kidney

L R

Inferior vena cava

Lower pole of left kidney Ureter

Aorta

Psoas muscles

Bladder

I

FIG. 7.99  Anterior view of urinary system.

CHAPTER 7  Abdomen Upper pole of left Perirenal Left Heart fat lung Diaphragm kidney S

Liver

449

Renal cortex

Calyx (major)

A

P

Stomach

Small intestine

Renal pelvis

FIG. 7.100  Sagittal CT reformat of left kidney.

S Renal (Gerota’s) fascia Adrenal gland

Pararenal fat

Perirenal fat L

R

Renal sinus

Calyx (minor) Renal pelvis Renal medulla (pyramid)

Ureter Renal cortex I

FIG. 7.101  Coronal midsection view of kidney.

I

Renal Lower pole Posterior pyramid of left abdominal kidney wall

450

CHAPTER 7  Abdomen Right kidney

Liver

Psoas muscle

Calyx (major) Spleen

S

R

L

I

Right adrenal gland

Renal pyramid

Left kidney

Renal cortex

FIG. 7.102  Coronal, T1-weighted MRI of kidneys.

Liver

Right adrenal gland

T12

S

Renal Renal Calyx pyramid pelvis (minor) (medulla) Spleen

R

L

Cortex of right kidney

Psoas muscle

L4

I

FIG. 7.103  Coronal CT reformat of kidneys.

Cortex of left kidney

Descending colon

CHAPTER 7  Abdomen

451

S Fibrous capsule Renal papilla Minor calyx

Renal cortex

Major calyx Renal pelvis Renal columns

Fat in renal sinus Ureter

Renal pyramids I

Nephron

Convoluted tubules

Glomerulus

Renal cortex

Thin descending limb Thick ascending limb

Loop of Henle

Renal medulla (pyramid)

Collecting duct

FIG. 7.104  Coronal midsection view of internal structures of kidney.

The kidneys can be divided into five segments according to their vascular supply: apical, anterosuperior (upper anterior), anteroinferior (middle inferior), inferior, and posterior (Fig. 7.109). The segmental classification helps with surgical planning for partial nephrectomies. The ureters are paired muscular tubes approximately 10 to 12 inches in length that transport urine to the urinary bladder. The upper half of the ureters are within the abdomen and the lower half within the pelvis. Each ureter originates at the renal pelvis and courses slightly anteriorly and medially and then descends the abdomen just anterior to the psoas muscles. (Figs. 7.108–7.111).

The ureters then enter the posterior wall of the bladder at an oblique angle (Fig. 7.111). Urine is excreted from the bladder through the urethra.

Renal agenesis is the failure of kidney formation during fetal development, resulting in the absence of one or both kidneys. Unilateral renal agenesis may be asymptomatic and is often incidentally diagnosed by abdominal computed tomography (CT) or ultrasound. Bilateral renal agenesis is invariably fatal.

452

CHAPTER 7  Abdomen

Liver

Right adrenal gland

Renal hilum

S

Left kidney

Perirenal fat

Spleen

R

L

Renal cortex

Right crus of diaphragm

I

Psoas muscle

Renal fascia

Abdominal wall

FIG. 7.105  Coronal CT reformat of kidneys in nephrogram phase.

Renal hilum

S

Renal cortex

R

Renal fascia

L

Renal pyramid

Calyx (minor)

I

Renal pelvis

FIG. 7.106  Coronal CT reformat of kidneys in excretory phase.

CHAPTER 7  Abdomen Renal hilum

Superior mesenteric vein

Superior mesenteric artery

A

453

3rd part of duodenum

Ascending colon L

R Renal cortex Renal medulla

Right renal pelvis

IVC

P

Aorta

Perirenal fat

Left kidney

FIG. 7.107  Axial, T1-weighted MRI of kidney. Renal hilum

Left ureter

A

Renal pyramid

Perirenal fat R

L

P

Renal pelvis

Calyx (minor)

Renal fascia

FIG. 7.108  Axial CT of kidney. Anterosuperior Apical

Apical

Apical

Anterosuperior

Posterior Anteroinferior

Inferior

Ureter

Inferior

Posterior Anteroinferior

Inferior

FIG. 7.109  Segments of right kidney.

454

CHAPTER 7  Abdomen

IVC

Right common iliac artery

A

Left common Lumbar iliac artery vertebra

Right ureter

Left ureter R

L

Psoas muscles

P

FIG. 7.110  Axial CT with ureters.

Sacral ala

Left ureter

S

Left renal pelvis

Left kidney

L5 R L

Right ureter

I Bladder

Superior pubic ramus

FIG. 7.111  3D CT urogram.

CHAPTER 7  Abdomen

STOMACH The stomach is the dilated portion of the digestive system that acts as a food reservoir and is responsible for the early stages of digestion. It has four major functions: (1) storage of food, (2) mechanical breakdown of food, (3) dissolution of chemical bonds via acids and enzymes, and (4) production of intrinsic factor, which is necessary for the absorption of vitamin B12. The stomach is located under the left dome of the diaphragm, with the superior portion joining the esophagus at the cardiac orifice and cardiac sphincter, creating the gastroesophageal junction (Figs. 7.112 and 7.115). The stomach has two borders called the lesser and greater curvatures. Between the two curvatures is the largest portion of the stomach, termed the body (Figs. 7.112, 7.113, and 7.116–7.118). On the superior surface of the body is a rounded surface called the fundus (Figs. 7.114 and 7.115). The inferior portion, the pyloric antrum, empties into the duodenum through the pyloric sphincter (Figs. 7.118 and 7.119). The anterior surface is in contact with the diaphragm, anterior

S

abdominal wall, and left lobe of the liver. Located posterior to the stomach are the spleen, the left adrenal gland and kidney, and the body and tail of the pancreas. When empty, the inner surface of the stomach creates prominent folds called rugae, which allow the stomach to expand with the ingestion of food (Figs. 7.112, 7.113, and 7.115). The stomach is one of the most vascular organs within the body. The arterial blood is supplied by branches of the gastric, splenic, and gastroduodenal arteries (Fig. 7.58). Venous drainage corresponds to the arterial supply. The gastric veins usually drain directly into the portal vein or into the superior mesenteric vein.

The average adult produces 2 to 3 liters per day of gastric juices, which contain mucus, hydrochloric acid, intrinsic factor, and the digestive enzymes pepsinogen and lipase. The stomach can hold up to 3 liters of food, which is mixed with digestive juices to form a semifluid mass called chyme.

Cardiac notch

S Esophagus

Fundus

Esophagus

Cardiac orifice

Pyloric portion Pyloric sphincter R

Angular notch

455

Lesser curvature

Pyloric sphincter

Body L Greater curvature

Duodenum

Pyloric canal

I

Pyloric antrum

R

Duodenal bulb

L Rugae

Duodenum

Pyloric orifice

FIG. 7.112  Stomach. Left, Anterior surface. Right, Internal surface.

I

456

CHAPTER 7  Abdomen Pyloric sphincter

S

Lesser curvature

Fundus

Body Rugae

Right lobe of liver

R

L

Duodenum

Greater curvature

I

FIG. 7.113  Coronal CT reformat of stomach.

CHAPTER 7  Abdomen

A

Left lobe of liver

457

Lesser omentum

Fundus of stomach

R

L Spleen

IVC

P

Right lobe of liver

FIG. 7.114  Axial, T1-weighted MRI of stomach.

A

Left lobe of liver

Rugae

Fundus of stomach R

L Spleen

Aorta

P

Gastroesophageal junction

FIG. 7.115  Axial CT of gastroesophageal junction.

458

CHAPTER 7  Abdomen Body of stomach

A

Left adrenal gland

R

L

P

Right adrenal gland

Pancreas

FIG. 7.116  Axial, T1-weighted MRI of stomach.

Body of pancreas

A

Air in body of stomach

Greater curvature

Lesser curvature

R

L

Spleen

IVC

P

FIG. 7.117  Axial CT of stomach.

CHAPTER 7  Abdomen

459

Air in body of stomach

A

Pyloric antrum

R

L

Pyloric sphincter

Duodenum

P

Head of pancreas

FIG. 7.118  Axial, T1-weighted MRI of pyloric antrum and pyloric sphincter.

Pyloric sphincter

Pyloric antrum

A

Air in stomach

R

L Spleen

Duodenum

IVC

P

Pancreas

FIG. 7.119  Axial CT of stomach with pyloric antrum and pyloric sphincter.

460

CHAPTER 7  Abdomen

INTESTINES The small intestine (small bowel) is located between the pylorus and ileocecal valve and consists of loops of bowel averaging 6 to 7 meters in length. It can be subdivided into the duodenum, jejunum, and the ileum (Figs. 7.120 and 7.121). The proximal portion of the small intestine is the duodenum, which begins at the gastric pylorus and curves around the head of the pancreas, forming the letter C (Figs. 7.118–7.122). The duodenum is mostly retroperitoneal, making it less mobile than the rest of the small intestine. Although quite short, the duodenum is divided into four portions. The first (superior) portion, located in the anterior pararenal space, is formed by the first 2 inches of the duodenum, the conical-shaped duodenal bulb. It is suspended in the abdomen by the hepatoduodenal ligament and is the most common site for peptic ulcer formation. The second (descending) portion is formed by the next 4 inches of the duodenum that descends along the right side of the vertebral column just anterior to the right renal hilum; it contains the ampulla of Vater and receives pancreatic and biliary drainage. The third (horizontal) portion is about 10 cm long and runs horizontally in front of the third lumbar vertebra. In its horizontal course from right to left, the third portion of the duodenum runs anterior to the IVC, aorta, and inferior mesenteric artery, and posterior to the superior mesenteric artery (Figs. 7.123 and 7.124). The fourth (ascending) portion is about 2.5 cm in length and ascends on the left side of the aorta to the level of the L2 vertebra, where it

meets up with the jejunum at the duodenojejunal flexure. The duodenojejunal flexure is fixed in place by the ligament of Treitz, a suspensory ligament created from the connective tissue located around the celiac trunk and left crus of the diaphragm (Fig. 7.122). This location marks the entry of the small bowel into the peritoneal cavity. The remainder of the small intestine, the jejunum and ileum, is suspended from the posterior abdominal wall by a fan-shaped mesentery. The jejunum is approximately 2.5 m long (about 40% of the small bowel) and occupies the left upper abdomen or umbilical region of the abdomen (Figs. 7.120–7.124). This section of small bowel is where the bulk of chemical digestion and nutrient absorption occurs. The jejunum contains numerous circular folds that give it a feathery appearance on diagnostic imaging examinations. It also has a thicker and more vascular wall than the ileum. The ileum is the longest portion of the small intestine, averaging 3.5 m in length (about 60% of the small bowel), and is located in the right lower abdomen (Figs. 7.120, 7.121, and 7.124–7.126). It is in the ileum that intrinsic factor from the stomach combines with vitamin B12 for absorption in the terminal ileum. Vitamin B12 is essential for normal red blood cell formation and nervous system function. The loops of ileum terminate at the ileocecal valve, a sphincter that controls the flow of material from the ileum into the cecum of the large intestine (Figs. 7.120, 7.121, and 7.127). The segments of the small intestine receive blood entirely from branches of the superior mesenteric artery and are drained by branches of the superior mesenteric vein.

Haustra Right colic (hepatic) flexure

Ileocecal valve

Ileum

Transverse colon Left colic (splenic) flexure

S

Descending colon

Ascending colon

Jejunum

R L

Epiploic appendages

Cecum Cecum

Orifice of appendix

Rectum

Vermiform appendix Ileum I

FIG. 7.120  Anterior view of small bowel.

CHAPTER 7  Abdomen

Duodenum

Pyloric sphincter

S

Lesser curvature

461

Stomach Greater curvature Transverse colon

Hepatic flexure

Splenic flexure L

R

Jejunum

Ascending colon

FIG.

I Ileocecal Cecum Ileum valve 7.121  Coronal CT reformat of small bowel.

First (superior) portion

Duodenal bulb

S

Pancreas

Second (descending) portion Villi R

L

Ampulla of Vater Third (horizontal) portion

Ligament of Treitz Duodenojejunal flexure

Fourth (ascending) portion

Jejunum I FIG. 7.122  Anterior view of duodenum and ligament of Treitz.

CHAPTER 7  Abdomen

462

Superior mesenteric vein

A

Superior mesenteric artery

Third (horizontal) portion of duodenum

R

L

P

IVC

Aorta

FIG. 7.123  Axial, T1-weighted MRI at third portion of duodenum.

Superior Superior mesenteric artery mesenteric vein

A

Transverse colon

Ilium

Third (horizontal) portion of duodenum Liver L

R

Jejunum

Ascending colon

IVC

P

Aorta

FIG. 7.124  Axial CT with third (horizontal) portion of duodenum.

Inferior mesenteric artery

CHAPTER 7  Abdomen

463

S Fundus of stomach Pancreas

Spleen

Portal vein

Splenic vein

Hepatic flexure

Duodenum

Jejunum

Ascending colon R

L

Cecum Ileocecal valve

Ilium

I

FIG. 7.125  Coronal CT reformat of small bowel and ileocecal valve.

Loops of ileum

A

R

Loops of jejunum

L

P

FIG. 7.126  Axial CT with ileum.

464

CHAPTER 7  Abdomen Ileocecal valve

Cecum

A

Ileum

R

L

P

FIG. 7.127  Axial CT with ileocecal valve. The large intestine (large bowel) lies inferior to the stomach and liver and almost completely frames the small intestine (Figs. 7.120 and 7.128). The large intestine has a larger diameter and thinner walls than the small intestine and is approximately 1.5 m long, starting at the ileocecal junction and ending at the anus. The outer, longitudinal muscle of the large intestine forms three thickened bands called taeniae coli, which gather the cecum and colon into a series of pouchlike folds

called haustra. On the outer surface of the large intestine are small fat-filled sacs of omentum called the epiploic appendages. The three main divisions of the large intestine are the cecum, colon, and rectum (Fig. 7.128). The cecum is a pouchlike section of the proximal portion of the large intestine and is about 7 cm in length. This is the location of the ileocecal valve and the slender vermiform appendix, which attaches to the posteromedial surface of the cecum (Figs. 7.128–7.130). The colon is S

Mesocolon

Right colic (hepatic) flexure

Left colic (splenic) flexure

Transverse colon Inferior mesenteric artery Superior mesenteric artery R

Taeniae coli L

Haustra

Descending colon

Ascending colon

Cecum Epiploic appendages

Ileum Vermiform appendix Rectum

Sigmoid colon

Anal canal

External anal sphincter I

FIG. 7.128  Anterior view of large intestine.

CHAPTER 7  Abdomen

S

Left lobe of liver

465

Stomach

Pancreatic duct

Right lobe of liver

Jejunum

L

R Transverse colon

Cecum Descending colon Ileum

I

FIG. 7.129  Coronal, T2-weighted MRI of cecum.

the longest portion of the large intestine and can be subdivided into four distinct portions: ascending, transverse, descending, and sigmoid (Figs. 7.131 and 7.132). The ascending colon is retroperitoneal and commences at the cecum, ascending the right lateral wall of the abdomen to the level of the liver. It then curves sharply to the left, creating the hepatic flexure (Figs. 7.128, 7.133, and 7.134). The hepatic flexure marks the beginning of the transverse colon. The transverse colon travels horizontally across the anterior abdomen toward the spleen, where it bends sharply downward, creating the splenic flexure and the beginning of the descending colon (Figs. 7.135 and 7.136). The transverse colon is located within the peritoneal cavity and is the largest and most mobile portion of the large intestine, making its position quite variable in the patient. The descending colon is retroperitoneal and continues inferiorly along the left lateral abdominal wall to the iliac fossa, where it curves to become the S-shaped sigmoid colon posterior to the

bladder (Fig. 7.128). The sigmoid colon joins the rectum, which is the terminal portion of the colon (Figs. 7.128, 7.132, 7.137, and 7.138). The rectum is considered a pelvic organ and is covered in greater detail in Chapter 8. The major functions of the large intestine include reabsorption of water and the storage and elimination of fecal material. The superior and inferior mesenteric arteries and veins supply and drain blood from the large intestine (Fig. 7.128). When the epiploic appendages become inflamed due to torsion or ischemia, it results in a condition called epiploic appendagitis. The condition commonly presents with acute lower quadrant pain, which can simulate appendicitis or diverticulitis. Epiploic appendagitis can occur at any age but is more common in the third through fifth decades. Treatment is somewhat controversial, but conservative therapy is generally favored because it is typically a self-limiting condition.

466

CHAPTER 7  Abdomen

Cecum

Ileum

A

Mesentery

Psoas muscles

R

L

Vermiform appendix

P

Sigmoid colon

FIG. 7.130  Axial CT of cecum and appendix.

Gallbladder

Haustra

S

Transverse colon

Jejunum

R

L

Ascending colon

Cecum

FIG. 7.131  Coronal MR colonography.

I

Ileum

Descending colon

CHAPTER 7  Abdomen Hepatic flexure

Transverse colon

Splenic flexure

S

Jejunum

Descending colon

R

L

Ascending colon

Ileum

Cecum Sigmoid colon

I Rectum

Anus

FIG. 7.132  3D CT of colon.

467

468

CHAPTER 7  Abdomen Hepatic flexure

Transverse colon

A

Superior mesenteric vein

Superior mesenteric artery

R

L

IVC

Inferior mesenteric vein

P

Inferior mesenteric artery

FIG. 7.133  Axial, T1-weighted MRI of hepatic flexure and transverse colon.

Hepatic flexure

IVC

A

Transverse colon

R

Aorta

Jejunum

L

Liver

P

FIG. 7.134  Axial CT of hepatic flexure and transverse colon.

CHAPTER 7  Abdomen Head of pancreas

Aorta

A

469

Air in stomach

Pyloric antrum

Pyloric sphincter R

L

Duodenum

P

IVC

Splenic flexure

FIG. 7.135  Axial, T1-weighted MRI of splenic flexure.

Transverse colon

Superior mesenteric vein

Superior mesenteric artery

Splenic flexure

A

Hepatic flexure R

L

Third (horizontal) portion of duodenum

FIG. 7.136  Axial CT of splenic flexure.

P

Aorta

Jejunum

470

CHAPTER 7  Abdomen Sigmoid colon

A

External iliac vein

External iliac artery

Iliopsoas muscle

R

L

Sacrum

P

Gluteus minimus muscle

Gluteus Gluteus medius maximus muscle muscle

FIG. 7.137  Axial, T1-weighted MRI of sigmoid colon.

Bladder

A

Femoral head

L

R

Sacrum

P

FIG. 7.138  Axial CT of sigmoid colon.

Sigmoid colon

Piriformis muscle

CHAPTER 7  Abdomen

471

bifurcates into the right and left common iliac arteries. The branches of the abdominal aorta can be divided into the paired branches, including the inferior phrenic, lumbar, suprarenal, renal, and gonadal arteries; and unpaired branches, which include the celiac trunk, splenic, superior mesenteric, and inferior mesenteric arteries (Figs. 7.139–7.142). Each of these branches has a typical configuration that is described in this text; however, many normal variations of these vessels may occur.

ABDOMINAL AORTA AND BRANCHES The abdominal aorta is a retroperitoneal structure beginning, as an extension of the thoracic aorta, at the aortic hiatus of the diaphragm. The abdominal aorta gradually diminishes in diameter as it descends the abdomen just left of the midline next to the vertebral bodies. It delivers blood to all the abdominopelvic organs and structures. At approximately the level of L4, the abdominal aorta

Right crus of diaphragm

Esophagus S

Diaphragm

Left gastric artery

Inferior phrenic artery

Celiac trunk

Common hepatic artery Splenic artery

Right suprarenal artery

Superior mesenteric artery

Right renal artery Right gonadal artery

Abdominal aorta

Lumbar arteries

Left gonadal artery

Right common iliac artery Inferior mesenteric artery Right internal iliac artery

Terminal segment of the aorta

Right external iliac artery Right inguinal ligament

Left internal iliac artery

I

FIG. 7.139  Anterior view of abdominal aorta.

472

CHAPTER 7  Abdomen S Spleen IVC Splenic artery

Left renal artery R

L Left renal vein Aorta Left common iliac artery Left external iliac artery I

Right kidney

Left internal iliac artery

FIG. 7.140  MRA of abdominal aorta.

Left hepatic artery

Common hepatic artery

Right inferior phrenic artery

S

Celiac trunk

Left gastric artery

Right renal artery Splenic artery Right hepatic artery

Superior mesenteric artery

Gastroduodenal artery

Right kidney R

L

Aorta

Lumbar artery Left common iliac artery

I Inferior mesenteric artery

FIG. 7.141  CD CTA of abdominal aorta.

CHAPTER 7  Abdomen S

473

Liver

Aorta

Celiac trunk A

P Superior mesenteric artery

Inferior mesenteric artery

I

FIG. 7.142  Sagittal MRA of abdominal aorta.

Paired Branches Inferior Phrenic Arteries.  The paired inferior phrenic arteries are the first to branch from the lateral surface of the abdominal aorta just as it descends through the aortic hiatus. The right inferior phrenic artery passes upward on the right side behind the IVC, and the left inferior phrenic artery passes behind the stomach and the abdominal part of the esophagus (Figs. 7.139, 7.141, and 7.143). The inferior phrenic arteries extend to supply the inferior surface of the diaphragm. Lumbar Arteries.  Four pairs of lumbar arteries arise

from the posterior wall of the abdominal aorta at the level of L1–L4 (Figs. 7.139 and 7.141). The lumbar arteries supply the posterior abdominal wall, lumbar vertebrae, and the intervertebral disks.

Inferior phrenic artery Superior suprarenal artery

Middle suprarenal artery

Adrenal gland

S Celiac trunk

Inferior suprarenal artery

Superior mesenteric artery

Kidney L R

Inferior mesenteric artery

Renal artery

Suprarenal Arteries.  These arteries course laterally

and slightly superiorly to supply the adrenal glands. The middle suprarenal arteries exit the lateral walls of the aorta near the base of the superior mesenteric artery. The superior suprarenal arteries are branches of the inferior phrenic arteries, and the inferior suprarenal arteries extend from the renal arteries (Figs. 7.90 and 7.143).

Renal Arteries.  The two large renal arteries arise

from the lateral walls of the aorta just below the superior mesenteric artery. Each vessel travels horizontally to the hilum of the corresponding kidney (Figs. 7.139– 7.141 and 7.143–7.148). Because of the position of the

Gonadal artery

Ureter

I

FIG. 7.143  Anterior view of paired branches of the abdominal aorta.

474

CHAPTER 7  Abdomen Superior mesenteric vein

A

Superior mesenteric artery Aorta

IVC R

L

Right renal artery

P

Left renal vein

aorta on the left side of the vertebral column, the right renal artery is slightly longer than the left renal artery. The right renal artery passes posterior to the IVC and right renal vein on its course to the right kidney (Fig. 7.144). Typically, the left kidney is higher than the right kidney, which means the left renal artery is generally slightly superior to the right (Fig. 7.145). As each renal artery reaches the renal hilum, it typically divides into anterior and posterior branches and then into five segmental arteries—apical, upper, middle, lower, and posterior—(Figs. 7.146 and 7.148). Each segmental artery further divides into interlobar arteries, one for each pyramid and adjoining cortex. As the interlobar arteries curve over the renal pyramids, they become the arcuate arteries from which the interlobular arteries arise to supply the renal cortex (Fig. 7.146).

Left renal artery

Renal artery stenosis causes renal ischemia and can result in secondary hypertension.

FIG. 7.144  Axial, T1-weighted MRI of abdomen with renal arteries and veins.

A

R

FIG. 7.145  Axial CT of abdomen with renal arteries and veins.

L

IVC

Aorta

P

Left renal Left renal artery vein

S

Upper segmental artery

Interlobar veins Renal pyramid

Apical segmental veins

Interlobar arteries

Suprarenal artery

Middle segmental artery

Renal artery

Renal cortex

Renal vein

Interlobular arteries

Lower segmental artery

Interlobular veins Arcuate veins Arcuate arteries

FIG. 7.146  Anterior view of renal vasculature.

I

CHAPTER 7  Abdomen S

Spleen

IVC

Splenic artery

Right renal artery R

L Left renal artery Left renal vein Aorta

Right common iliac artery

I

Right Right external internal iliac artery iliac artery

FIG. 7.147  MRA of renal arteries. Right inferior phrenic artery

Right renal artery

S

Superior Left Celiac mesenteric renal trunk artery artery

Interlobar arteries

Upper segmental artery

L

R Anterior division of renal artery

Lower segmental artery

I

Inferior mesenteric artery

FIG. 7.148  CTA of renal arteries.

475

476

CHAPTER 7  Abdomen

Gonadal Arteries.  The gonadal arteries originate from

the male, the gonadal arteries are termed the testicular arteries, which supply the testes and scrotum, whereas the gonadal arteries in the female are termed the ovarian arteries, which supply the ovaries, uterine tubes, and uterus.

the anterior wall of the aorta just inferior to the renal arteries. They descend along the psoas muscles to reach their respective organs (Figs. 7.139, 7.149, and 7.150). In

IVC

Aorta

A

Ureter

R

L

Ureter

Psoas muscle

Left gonadal vein

P

Left gonadal artery

FIG. 7.149  Axial, T1-weighted MRI of abdomen and gonadal arteries and veins.

IVC

Aorta

A

R

L

Right ureter

Psoas muscle

Right gonadal artery

P

Right gonadal vein

FIG. 7.150  Axial CT of abdomen and gonadal arteries and veins.

CHAPTER 7  Abdomen

Unpaired Branches Celiac Trunk.  The celiac trunk is a very short vessel that leaves the anterior wall of the aorta just after the aorta passes through the diaphragm. The short celiac trunk divides into three branches: left gastric, common hepatic, and splenic arteries (Figs. 7.151–7.153). Variations of the celiac trunk are not rare; occasionally, the common hepatic artery will branch directly from the superior mesenteric artery.

The left gastric artery courses superiorly and toward the left within the lesser omentum to supply the cardiac region of the stomach, then passes along the lesser curvature toward the pylorus, giving off esophageal and gastric branches to supply the abdominal esophagus and adjacent anterior and posterior walls of the body of the stomach. The left gastric artery continues toward the right to anastomose with the right gastric artery (Figs. 7.151, 7.154, 7.155, and 7.157).

Stomach

S

Left gastric artery Splenic artery Left hepatic artery Right hepatic artery Celiac trunk Right gastric artery

Spleen R

Proper hepatic artery L

Common hepatic artery Gastroduodenal artery

Left gastroepiploic artery

Anterior superior pancreaticoduodenal artery Pancreas

I Right gastroepiploic artery

FIG. 7.151  Anterior view of celiac trunk and branches. Portal vein

A

Stomach Splenic artery R

L

Spleen

IVC

477

Common hepatic artery

P

Aorta

Celiac trunk

FIG. 7.152  Axial, T1-weighted MRI of abdomen with celiac trunk.

478

CHAPTER 7  Abdomen Portal vein

Splenic artery

A

Stomach

R

L Spleen

Common Right crus hepatic artery of diaphragm

P

Aorta

Celiac trunk

FIG. 7.153  Axial CT of abdomen with celiac trunk.

Portal vein

A

Left gastric artery

Stomach

R

L

Spleen

IVC

Crus of diaphragm

P

Aorta

FIG. 7.154  Axial, T1-weighted MRI of abdomen with left gastric artery.

CHAPTER 7  Abdomen

A

Left gastric artery

R

L

P

IVC

Aorta

Celiac trunk

FIG. 7.155  Axial CT of abdomen with left gastric artery.

Gastroduodenal artery

Proper hepatic artery

Common hepatic artery S

Splenic artery

R

L

Right renal artery

Splenic artery

Right gonadal artery

I

Left common iliac artery

Left gonadal artery

FIG. 7.156  MRA with branches of celiac trunk.

Left renal artery

479

480

CHAPTER 7  Abdomen Common hepatic artery

Celiac trunk

S

Left gastric artery

Splenic artery

Left hepatic artery Right hepatic artery

Superior mesenteric artery

Proper hepatic artery

Right gastric artery

Gastroduodenal artery R L Superior pancreaticoduodenal artery

Inferior mesenteric artery

I

FIG. 7.157  3D CTA of celiac trunk.

The common hepatic artery crosses to the right toward the superior aspect of the duodenum and divides into the proper hepatic artery and the gastroduodenal artery (Figs. 7.151–7.153, 7.156, and 7.157). The proper hepatic artery ascends obliquely to the right in the hepatoduodenal ligament, adjacent to the portal vein and CBD, divides near the porta hepatis into the right and left hepatic branches, and usually gives off the right gastric artery (Figs. 7.151, 7.156, and 7.157). The right hepatic branch dispatches the cystic artery to the gallbladder and divides into the anterior and posterior segmental arteries to supply the segments of the right and caudate lobes of the liver. The left hepatic branch also gives off an artery to the caudate lobe, as well as medial and lateral segmental arteries to supply the segments of the left lobe and the intermediate branch to the quadrate lobe. The right gastric artery, which can also arise from the common hepatic or

gastroduodenal arteries, supplies the lower part of the lesser curvature of the stomach and anastomoses with the left gastric artery within the lesser curvature of the stomach (Figs. 7.151 and 7.157). The gastroduodenal artery descends behind the pylorus to give off many branches, including the anterior and posterior superior pancreaticoduodenal arteries, which supply the superior part of the duodenum and head of the pancreas, and the right gastroepiploic (gastro-omental) artery. The right gastroepiploic artery passes through the greater omentum, anastomoses with the left gastroepiploic artery on the inferior surface of the greater curvature, and dispatches numerous gastric branches to the anterior and posterior walls of the pyloric and body portions of the stomach (Figs. 7.151 and 7.156–7.158). The splenic (lienal) artery is the largest branch of the celiac trunk and passes to the left behind the stomach

CHAPTER 7  Abdomen Inferior vena cava

Aorta Celiac axis Splenic artery and vein

Left hepatic artery Right hepatic artery

481

S

Main portal vein

Body

Proper hepatic artery Common hepatic artery

Spleen Gastroduodenal artery Posterior superior pancreaticoduodenal artery Duodenum

Tail

L

Great pancreatic artery R

Dorsal pancreatic artery Uncinate process

Head Anterior superior pancreaticoduodenal artery

Superior mesenteric artery and vein

Anterior interior I pancreaticoduodenal artery Inferior vena cava

Aorta

FIG. 7.158  Anterior view of hepatic artery, CBD, and portal vein. (Fig. 7.159). Just before the splenic artery terminates into numerous splenic branches, it gives rise to the left gastroepiploic (gastro-omental) artery, which gives off epiploic and gastric branches to the greater omentum and anterior and posterior walls of the fundus of the stomach (Figs. 7.151 and 7.156–7.161).

and along the upper border of the pancreas, within the splenorenal ligament, to the hilum of the spleen. At the point where the splenic artery courses near the border of the pancreas, it gives off numerous pancreatic branches including the dorsal, great, and caudal pancreatic arteries that supply the body and tail of the pancreas

Left gastric artery S

Stomach

Celiac trunk Common hepatic artery L R Superior mesenteric artery

Caudal pancreatic branch

I Splenic artery

Pancreas Dorsal pancreatic branch

Great pancreatic branch

Spleen Left gastroepiploic artery

FIG. 7.159  Anterior view of splenic artery.

482

CHAPTER 7  Abdomen Splenic artery

A

Stomach R

L

Spleen

IVC

Aorta

P

Splenic vein

FIG. 7.160  Axial, T1-weighted MRI of splenic artery.

Celiac trunk

A

Left gastric artery

Stomach

R

L

IVC

Right adrenal gland

P

Right crus

Splenic artery

Spleen

FIG. 7.161  Axial CT of splenic artery.

Superior Mesenteric Artery.  The large superior mesenteric artery (SMA) emerges just below the celiac trunk at approximately the level of L1 (Figs. 7.139, 7.162, and 7.163). It descends behind the body of the pancreas, then over the horizontal portion of the duodenum to course in the mesentery to the ileum (Figs. 7.158, 7.162, and

7.164–7.167). The artery supplies the head of the pancreas and the majority of the small and large intestines. Branches of the superior mesenteric artery include the inferior pancreaticoduodenal artery, jejunal arteries, ileal arteries, middle colic artery, right colic artery, and ileocolic artery. The inferior pancreaticoduodenal artery

CHAPTER 7  Abdomen Celiac trunk

S

483

L1

Left renal vein

Body of pancreas Abdominal aorta

SMA A

P

Horizontal portion of duodenum

I

L5

FIG. 7.162  Sagittal CT reformat of superior mesenteric artery.

Duodenum

A

Splenic vein

R

Pancreas

L

SMV

IVC

P

Aorta

FIG. 7.163  Axial CT with superior mesenteric artery.

SMA

484

CHAPTER 7  Abdomen Ileum SMV

SMA

A

R

L

IVC

Aorta

P

IMV

IMA

FIG. 7.164  Axial, T1-weighted MRI of superior mesenteric vessels.

Gonadal artery Ileum

Mesenteric vessels A

R

L

Ureter

Psoas muscle

IVC

P

Aorta

IMA

FIG. 7.165  Axial CT of inferior mesenteric vessels. extends to the head of the pancreas and duodenum, and then divides into the posterior ramus, which anastomoses with the posterior superior pancreaticoduodenal artery, and the anterior ramus, which anastomoses with the anterior superior pancreaticoduodenal artery. The jejunal and ileal arteries extend to supply the jejunum and ileum, except the end segment near the cecum. The middle

colic artery reaches the transverse colon, and the right colic artery passes to the ascending colon. The ileocolic artery courses behind the peritoneum across the right ureter into the right iliac fossa and divides to supply a portion of the ascending colon, cecum, vermiform appendix, and terminal portion of the ileum (Figs. 7.166 and 7.168).

CHAPTER 7  Abdomen S

Celiac trunk

Duodenum Aorta Superior mesenteric artery

Transverse mesocolon Transverse colon

Posterior ramus Inferior pancreaticoduodenal arteries

Right colic artery

Middle colic artery

Ileocolic artery Ascending branch of ileocolic artery

L Jejunum

R

Jejunal arteries

Ileal branch of ileocolic artery

Arterial arcades

Ascending colon

Ileal arteries

Cecal artery Ileum

Posterior cecal artery Appendix

Appendicular artery I

FIG. 7.166  Anterior view of branches of superior mesenteric artery.

S

Liver

Celiac axis A

P

SMA

IMA

I

FIG. 7.167  Sagittal MRA of superior mesenteric artery.

485

CHAPTER 7  Abdomen

486

Common hepatic artery

Celiac trunk

S

Left gastric artery

Splenic artery

Proper hepatic artery Gastroduodenal artery Right renal artery

SMA Jejunal branches L

R Right colic artery

Ileal branches

Ileocolic artery

IMA

Right common iliac artery

I

FIG. 7.168  3D CTA of superior and inferior mesenteric arteries. Common hepatic artery

S

S

Splenic artery

Pancreas

Aorta

Transverse mesocolon Transverse colon Superior mesenteric artery

Descending colon

Duodenum

L

Marginal artery Inferior mesenteric artery

R Left common iliac artery

L

R

Left colic artery Superior rectal artery

Sigmoid arteries Sigmoid colon

I

FIG. 7.169  Anterior view of inferior mesenteric artery.

Right renal artery

Right gonadal artery

Left gonadal artery

I

Inferior mesenteric artery

Left renal artery

FIG. 7.170  MRA of inferior mesenteric artery (IMA).

CHAPTER 7  Abdomen

Inferior Mesenteric Artery.  The inferior mesenteric artery (IMA) arises 3 to 4 cm above the bifurcation of the aorta at approximately the level of L3–L4. It descends in front of the abdominal aorta and then to the left, where it gives off the left colic artery, sigmoid arteries, and the superior rectal artery (Figs. 7.164, 7.165, and 7.169). The left colic artery is a retroperitoneal structure that passes along the anterior surface of the left psoas and quadratus

487

lumborum muscles. It bifurcates into ascending and descending branches that supply the walls of the left third of the transverse colon and the entire descending colon. The sigmoid branches (2 or 3) course within the mesentery to supply branches to the terminal descending colon and to the sigmoid colon. The superior rectal artery crosses the common iliac artery and vein as it descends to branch and supply the rectum (Figs. 7.169–7.171).

Common hepatic artery

Celiac trunk

Left gastric artery

Splenic artery

S

Proper hepatic artery

Gastroduodenal artery SMA

L

R

IMA Aorta Left colic artery

Sigmoid artery

I Superior rectal artery

FIG. 7.171  3D CTA of inferior mesenteric artery (IMA).

488

CHAPTER 7  Abdomen

INFERIOR VENA CAVA AND TRIBUTARIES

vein, left renal vein, or the IVC. The right inferior phrenic vein drains directly into the IVC (Fig. 7.172).

The inferior vena cava (IVC) is the largest vein of the body (Fig. 7.172). It carries blood to the heart from the lower limbs, pelvic organs and the abdominal viscera, and abdominal wall. The IVC is formed by the union of the common iliac veins at approximately the level of L5. It courses superiorly through the retroperitoneum along the anterior aspect of the vertebral column and to the right of the aorta (Figs. 7.164 and 7.165). As the IVC ascends the abdominal cavity, it passes along the posterior surface of the liver and enters the thorax at the caval hiatus to enter the right atrium of the heart. The IVC receives many tributaries, including the inferior phrenic, lumbar, right gonadal, renal, right suprarenal, and hepatic veins, throughout its course in the abdomen (Fig. 7.172).

Lumbar Veins The lumbar veins consist of four pairs of vessels that collect blood from the posterior abdominal wall at the L1–L4 levels (Figs. 7.173–7.175). They receive veins from the vertebral plexuses and then travel horizontally along the transverse processes of the vertebrae deep to the psoas muscles. The lumbar veins on the left are typically longer than those on the right because they must cross over the vertebral column to drain into the IVC. The arrangement of these veins varies, with some entering the lateral walls of the IVC and others emptying into the common iliac vein or are united on each side by a vertical connecting vein termed the ascending lumbar vein. Typically, the right ascending lumbar vein continues as the azygos vein and the left ascending lumbar vein continues as the hemiazygos vein. Additionally, a diminutive median sacral vein may accompany the median sacral artery. It typically drains into the left common iliac vein but may also drain into the junction of the common iliac veins (Figs. 7.172 and 7.173).

Inferior Phrenic Veins The inferior phrenic veins extend from the inferior surface of the diaphragm. The left inferior phrenic vein is often doubled and drains into either the left suprarenal

Right inferior phrenic vein

Caval hiatus

Left inferior phrenic vein

S

Inferior phrenic artery

Hepatic veins

Left gastric artery Suprarenal artery Suprarenal vein

Celiac trunk

Right renal artery

Splenic artery

Right renal vein

Hepatic artery R

L

Inferior vena cava

Abdominal aorta Superior mesenteric artery

Testicular or ovarian artery

Inferior mesenteric artery

Testicular or ovarian veins

Common iliac artery

Middle sacral artery

Common iliac vein

Middle sacral vein

External iliac artery

Internal iliac artery

External iliac vein

Internal iliac vein I

Ureters

FIG. 7.172  Anterior view of abdominal aorta and IVC.

CHAPTER 7  Abdomen S Hepatic veins Inferior phrenic Hemiazygos

Subcostal lumbar Right suprarenal First lumbar

Renal

Ascending lumbar Second lumbar

R L Right gonadal

Third lumbar Third lumbar Fourth lumbar

Fourth lumbar

Iliolumbar

Common iliac

FIG. 7.173  Anterior view of IVC and lumbar veins.

Median sacral

I

Inferior vena cava

S

S

Lumbar vertebra

Lumbar veins

A

P Lumbar vein

I

FIG. 7.174  Sagittal, T1-weighted MRI with lumbar veins.

I

FIG. 7.175  Sagittal CT reformat with lumbar veins.

489

490

CHAPTER 7  Abdomen which carry blood from the medulla to the interlobar veins. The interlobar veins drain into the segmental veins. The five segmental veins correspond to the respective segmental arteries and merge to form the renal vein (Fig. 7.146). The renal veins pass anterior to the renal arteries to empty into the IVC at about the level of L2. The left renal vein passes posterior to the superior mesenteric artery and anterior to the aorta on its route from the left kidney to enter the left lateral wall of the IVC. It receives the left gonadal vein, left inferior phrenic vein, and generally the left suprarenal vein. The shorter right renal vein is typically lower than the left renal vein as it travels its short course to enter the right lateral wall of the IVC (Figs. 7.172, 7.173, 7.176, and 7.177).

Gonadal Veins The gonadal veins, ovarian in females and testicular in males, ascend the abdomen along the psoas muscle, anterior to the ureters. The right gonadal vein enters the anterolateral wall of the IVC just below the opening for the right renal vein, whereas the left gonadal vein typically empties directly into the left renal vein (Figs. 7.149, 7.150, 7.172, and 7.173).

Renal Veins Blood leaves the kidney by way of interlobular veins that carry blood from the renal cortex to the arcuate veins,

Pancreas

A

Left renal vein

Gallbladder

R

L

Duodenum

Right renal vein

IVC

P

Aorta

SMV

FIG. 7.176  Axial, T1-weighted MRI with renal veins.

A

Left renal vein SMA

R

L

Right renal vein

IVC

P

FIG. 7.177  Axial CT with renal veins.

Aorta

CHAPTER 7  Abdomen

491

Suprarenal Veins

LYMPH NODES

The right suprarenal vein courses from the medial side of the right adrenal gland to empty directly into the IVC. The left suprarenal vein courses from the inferior pole of the left adrenal gland to empty directly into the left renal vein or left inferior phrenic vein (Figs. 7.172 and 7.173).

Many lymph nodes exist within the abdominal cavity. Abdominal lymph nodes occur in chains along the main branches of the arteries of the intestine and abdominal aorta. Most abdominal lymph nodes appear as small oblong soft tissue masses oriented parallel to their accompanying vessels and may be difficult to visualize in cross-section unless they are enlarged as a result of an abnormality. Typically, lymph nodes are considered enlarged if their short axis diameter is greater than 1 cm. Abdominal nodal groups surround the aorta and IVC and organs of the abdomen. Lymph from the abdominal cavity empties into the lumbar trunks, which drain lymph from the legs, lower abdominal wall, and the pelvic organs; and the intestinal trunks, which drain organs located within the abdominal cavity. These trunks then join the thoracic duct and ultimately enter the venous system (see Chapter 6, Figs. 6.34–6.36, and Figs. 7.178–7.180).

Hepatic Veins The three short hepatic veins (right, middle, left) begin as smaller vessels that collect blood from the liver parenchyma. The hepatic veins course from the inferior aspect of the liver to the superior aspect of the liver, where they empty into the IVC just below the diaphragm. In general, the right and left hepatic veins drain the right and left lobes of the liver, respectively, whereas the middle hepatic vein drains the medial segment of the left lobe and the anterior portions of the right lobe (see liver section, Figs. 7.63–7.68 and 7.172).

S

Celiac nodes Thoracic duct Superior mesenteric nodes Cisterna chyli

Intestinal trunk of cisterna chyli

Lumbar trunks of cisterna chyli

Lumbar (para-aortic) nodes

R

L

Right lumbar (retrocaval) nodes

Inferior mesenteric nodes

Aortocaval nodes

Common iliac nodes

External iliac nodes

Internal iliac (hypogastric) nodes

I

FIG. 7.178  Anterior view of lymphatic system.

492

CHAPTER 7  Abdomen Gastrodoudenal artery

Head of pancreas

A

Superior mesenteric vein

Gallbladder

Duodenum R

L

Common bile duct IVC P

Superior mesenteric artery

Aorta

Spleen

FIG. 7.179  Axial CT of upper abdomen with enlarged lymph nodes (arrows). A

R

L

IVC

Aorta

P

FIG. 7.180  Axial CT of abdomen with enlarged lymph nodes (arrows) in small bowel mesentery.

MUSCLES OF THE ABDOMINAL WALL The abdominal wall is formed superiorly by the diaphragm and is inferiorly continuous with the pelvic cavity at the pelvic inlet. Posteriorly, the abdominal wall is formed by the five lumbar vertebrae, the 12th pair of ribs, the upper portion of the pelvis, quadratus lumborum muscles, and psoas muscles (Fig. 7.181). The quad­ ratus lumborum muscle forms a large portion of the posterior abdominal wall. It extends from the iliac crest to the inferior border of the 12th rib and transverse processes of the lumbar vertebrae to aid in lateral flexion of the vertebral column. The large psoas muscles extend along the lateral surfaces of the lumbar vertebrae to

insert on the lesser trochanter of the femur and act to flex the thigh and trunk (Figs. 7.182–7.184). Anteriorly, the abdominal wall is formed by the lower portion of the thoracic cage and by layers of muscles that include the rectus abdominis, external oblique, internal oblique, and transversus abdominis (Figs. 7.185 and 7.186). The paired rectus abdominis muscles, visualized on the anterior surface of the abdomen and pelvis, originate from the pubic symphysis and extend vertically to the xiphoid process and costal cartilage of the fifth, sixth, and seventh ribs. They function to flex the lumbar vertebrae and support the abdomen (Figs. 7.182 and 7.184). The anterior surface of the rectus abdominis muscle is crossed by three tendinous intersections that course transversely,

CHAPTER 7  Abdomen

493

S

External intercostal muscle Esophagus Inferior vena cava Central tendon Diaphragm Aorta L Left crus

Right crus

Quadratus lumborum muscle

R Psoas major muscle

Iliac crest Iliacus muscle

Psoas minor muscle

Anterior superior iliac spine Inguinal ligament Iliopsoas muscle

Pubic tubercle

I Lesser trochanter of femur

FIG. 7.181  Anterior view of psoas and quadratus lumborum muscles.

Aponeurosis of oblique muscles External oblique muscle

Internal oblique muscle

Rectus abdominis muscle

A

Transversalis fascia L Lumbar vertebra

R

Psoas major muscle

Transversus abdominis muscle Quadratus lumborum muscle

Erector spinae muscle group P

forming individual muscle bellies that can contract separately (Fig. 7.185). A longitudinal band of fibers that forms a central anterior attachment for the muscle layers of the abdomen is the linea alba, which extends from the xiphoid process of the sternum to the pubic symphysis.

FIG. 7.182  Axial view of the abdominal wall. The linea alba is formed, at the midline, by the interlacing of fibers from the rectus abdominis and oblique muscles (Figs. 7.184– 7.186). The external and internal oblique muscles are located on the outer lateral portion of the abdomen and extend from the cartilages of the

494

CHAPTER 7  Abdomen Psoas muscle

Quadratus lumborum muscle

A

R

L

Iliocostalis muscle

Longissimus muscle

P

Transversospinal (multifidus) muscle

FIG. 7.183  Axial, T2-weighted MRI of psoas and quadratus lumborum muscles.

Rectus abdominis muscle

A

Linea alba

Transversus abdominis muscle

Internal oblique muscle

External oblique muscle

R

L

Right common iliac artery Left common iliac artery

Quadratus lumborum muscle

Erector spinae muscle

P Transversospinal (multifidus) muscle

Psoas muscles

FIG. 7.184  Axial CT of psoas and quadratus lumborum muscles.

lower ribs to the level of the iliac crest (Figs. 7.182, 7.184, 7.186, and 7.187). The oblique muscles work together to flex and rotate the vertebral column and compress the abdominal viscera. The external oblique is the most extensive of the three broad abdominal muscles and contains a triangular opening, the superficial inguinal ring, that allows for the passage of the spermatic cord or round ligament of the uterus (Fig. 7.185). The inguinal ligament is a fibrous band formed by the thickened inferior border of the aponeurosis of the external oblique muscle. It extends from the anterior superior

iliac spine to the pubic tubercle and gives rise to the lowermost fibers of the internal oblique and transversus abdominis muscles (Fig. 7.186). The transversus abdominis muscle lies deep to the internal oblique muscles. Its fibers extend transversely across the abdomen to provide maximum support for the abdominal viscera. The transversus abdominis muscle extends from the lower six costal cartilages, lumbar fascia, iliac crest, and inguinal ligament to insert into the xiphoid process, linea alba, and pubic symphysis (Figs. 7.182, 7.184, 7.186, and 7.187 and Table 7.3).

CHAPTER 7  Abdomen S Pectoralis major

Latissimus dorsi

Serratus anterior

Tendinous intersections

Linea alba

External oblique

R

L Rectus abdominis

External oblique aponeurosis

Rectus sheath (cut) Superficial (external) inguinal ring

Spermatic cord I

FIG. 7.185  Anterior view of muscles of abdominal wall.

S

Costal cartilage External intercostal

Rib

Internal intercostal Internal oblique aponeurosis

Transversus abdominis R

L Internal oblique

Linea alba Arcuate line Rectus abdominis (cut)

Anterior superior Iliac spine

Inguinal ligament

Inguinal canal

Pubic symphysis

I

Pubic tubercle

FIG. 7.186  Anterior view of rectus abdominis muscle.

495

CHAPTER 7  Abdomen

496

S

Stomach Spleen External oblique muscle

IVC

Internal oblique muscle

Descending colon R

L

Right kidney Transversus abdominis muscle

Left psoas muscle

Ascending colon

Iliacus muscle I

FIG. 7.187  Coronal CT reformat of psoas muscles.

TABLE 7.3

Abdominal Muscles

Muscle

Origin

Insertion

Function

Rectus abdominis

Pubic bone near symphysis

Flexes trunk

External oblique

Lower eight ribs

Costal cartilage of fifth, sixth, and seventh ribs; xiphoid process of sternum Linea alba and iliac crest

Internal oblique

Iliac crest, lumbodorsal fascia, and inguinal ligament Lower six ribs, iliac crest, and lumbodorsal fascia Iliac crest

Transversus abdominis Quadratus lumborum Psoas

Vertebral bodies, intervertebral disks, and transverse processes of T12–L5

REFERENCES Anderson, M. W., & Fox, M. G. (2017). Sectional anatomy by MRI and CT (4th ed.). Philadelphia: Elsevier. Couinaud C. Le foie. Etudes anatomiques et chirurgicales. The Liver. Anatomical and surgical investigations. Paris; Masson; 1957 Federle, M. P., & Raman, S. P. (2015). Diagnostic imaging: Gastrointestinal (3rd ed.). Philadelphia: Elsevier. Frank, G. (2012). Merrill’s atlas of radiographic positions and radiologic procedures (12th ed.). St. Louis: Mosby. Haaga, J. R., & Boll, D. T. (2017). CT and MRI of the whole body (6th ed.). Philadelphia: Elsevier.

Lower three ribs, linea alba Pubic bone and linea alba Twelfth rib and transverse processes of lumbar vertebrae Lesser trochanter of femur

Compresses abdominal viscera, flexes and rotates spine Compresses abdominal viscera, flexes and rotates spine Compresses abdominal viscera Flexes spine laterally Lateral flexion of the trunk and flexor of the hip

Hagen-Ansert, S. L. (2012). Textbook of diagnostic sonography (7th ed.). St. Louis: Elsevier. Sahani, D. V., & Samir, A. E. (2017). Abdominal imaging (2nd ed.). Philadelphia: Elsevier. Seidel, H. M., Ball, J. W., & Dains, J. E., et al. (2010). Mosby’s guide to physical examination (7th ed.). St. Louis: Mosby. Standring, S. (2012). Gray’s anatomy, the anatomical basis of clinical practice (41st ed.). New York: Elsevier. Torigian, D. A., & Kitazono, M. T. (2013). Netter’s correlative imaging: Abdominal and pelvic anatomy (1st ed.). Philadelphia: Elsevier. Weir, J., & Abrahams, P. H. (2011). Imaging atlas of human anatomy (4th ed.). London: Elsevier.

CHAPTER

8

Pelvis These, gentlemen, are the tuberosities of the ischia, on which man was designed to sit and survey the works of creation. Oliver Wendell Holmes (1809–1894), Life and Letters of Oliver Wendell Holmes, Vol. I, Chapter VII S

Sacrum Endometrial carcinoma of the uterus A

P

The pelvis provides structural support for the body and encloses the male and female reproductive organs. Because of its role as a support mechanism for the body, the pelvis has a large amount of musculoskeletal anatomy, which, together with the differences in male and female reproductive anatomy, makes this area challenging to learn (Fig. 8.1).

Bladder Pubic bone

FIG. 8.1  Sagittal, T1-weighted contrast-enhanced MRI of the pelvis demonstrating endometrial carcinoma of the uterus.

I

OBJECTIVES • • • • • •

Identify the structures of the bony pelvis. Define the pelvic inlet and outlet. Describe the perineum. Describe the function and location of the pelvic muscles. Differentiate between the pelvic diaphragm and perineum. Describe the location of the bladder in relation to the reproductive organs and the course of the male and female urethras.

• Describe the location and function of the male and female reproductive organs. • Identify the major arteries and veins that are located within the pelvis. • Describe the location of the pelvic lymph nodes. • List and describe the components of the rectum.

OUTLINE BONY PELVIS, 498 Sacrum, Coccyx, and Hip Bones (Innominate Bones), 498 Pelvic Inlet and Outlet, 506 MUSCLES, 507 Extrapelvic Muscles, 507 Pelvic Wall Muscles, 510

Pelvic Diaphragm (Pelvic Floor) Muscles, 513 Perineum, 518 VISCERA, 520 Bladder, 520 Rectum, 527 Female Reproductive Organs, 529

Copyright © 2019, Elsevier Inc.

Male Reproductive Organs, 540 VASCULATURE, 555 Arteries, 555 Venous Drainage, 563 LYMPH NODES, 565

497

498

CHAPTER 8   Pelvis

BONY PELVIS Sacrum, Coccyx, and Hip Bones (Innominate Bones)

on both the anterior and posterior surfaces (Figs. 8.9– 8.11). The body of the ilium creates the upper portion of the acetabulum, which is a deep fossa that articulates with the head of the femur (Figs. 8.13 and 8.14).

The bony pelvis is formed by the sacrum, coccyx, and two hip bones or innominate bones (Figs. 8.2 and 8.3). The sacrum is a triangular-shaped bone formed by the fusion of five vertebral segments. The first sacral segment has a prominent ridge located on the anterior surface of the body termed the sacral promontory, which acts as a bony landmark separating the abdominal cavity from the pelvic cavity (Figs. 8.3 and 8.5). The transverse processes of the five sacral segments combine to form the lateral mass (ala), which articulates with the hip bones at the sacroiliac joints (Figs. 8.3–8.5). The lateral mass contains sacral foramina that allow for the passage of sacral nerves (Figs. 8.2, 8.6, and 8.7). Articulating with the fifth sacral segment is the coccyx, which consists of three to five small fused bony segments (Figs. 8.2, 8.3, and 8.8). The hip bones are made up of three bones: the ilium, pubis, and ischium (Fig. 8.9).

rior portion of the acetabulum and consists of a body and superior and inferior pubic rami (Fig. 8.9). The bodies of the two pubic bones meet at the midline to form the pubic symphysis (Figs. 8.2, 8.12, and 8.15). The superior pubic ramus projects inferiorly and medially from the acetabulum to the midline of the body (Figs. 8.2, 8.3, and 8.16). Located on the upper surface of the superior pubic ramus is a ridge termed the pectineal line, which is continuous with the arcuate line of the ilium, forming the pelvic brim (Fig. 8.12). Also on the superior surface is the pubic tubercle, which is the attachment site for the inguinal ligament (Figs. 8.2 and 8.3). The inferior pubic ramus projects inferiorly and laterally from the body to join the ischium at an indistinct point; therefore the two together are often referred to as the ischiopubic ramus (Figs. 8.11 and 8.17).

Ilium.  The ilium, the largest and most superior portion,

Ischium.  The ischium is the inferior portion of the hip

Pubis.  The pubis, or pubic bone, forms the lower ante-

consists of a body and a large winglike projection called the ala (Figs. 8.9–8.11). The concave, anterior surface of the ala is termed the iliac fossa, which is separated from the body by the arcuate line. This arch-shaped line, which is located on the anterior surface of the ilium, forms part of the pelvic brim (Figs. 8.11 and 8.12). The superior ridge of the ala is termed the iliac crest; it slopes down to give rise to the superior and inferior iliac spines

Iliac fossa

bones and, like the pubis, is composed of a body and two rami. The body of the ischium forms the lower posterior portion of the acetabulum (Figs. 8.9, 8.11, 8.13, and 8.14). The superior ischial ramus extends posteriorly and inferiorly to a roughened, enlarged area termed the ischial tuberosity (Figs. 8.9, 8.10, and 8.17). From the ischial tuberosity, the inferior ischial ramus extends anteriorly and medially to join the inferior pubic ramus.

Sacroiliac joints

Sacrum Lateral mass (ala)

S Iiac crest

Ala of ilium

Ilium Arcuate line

Sacral foramina L

R

Pectineal line

Acetabulum Coccyx

Obturator foramen

I Pubic symphysis

Superior pubic ramus

Ischium Pubic tubercle

Inferior pubic ramus

FIG. 8.2  Anterior view of pelvis.

CHAPTER 8   Pelvis

Arcuate line

Coccyx

Sacral promontory

L5

Sacrum

499

Sacroiliac joint

S Ala of ilium

Iliac fossa

Anterior superior iliac spine

Acetabulum L R

Femoral head

Pectineal line Femoral neck Greater trochanter Obturator foramen

Lesser trochanter

Ischium

Ischial tuberosity

Pubic symphysis

I

Pubic tubercle

Inferior pubic ramus

Superior pubic ramus

FIG. 8.3  3D CT of pelvis, anterior view.

Iliacus muscle

Psoas muscle

A

Linea alba

Rectus abdominis muscle

Lateral mass of sacrum

Ala of lilium

Gluteus medius muscle L

R

Ilium

Sacrum

Sacral foramen Gluteus maximus muscle

Sacroiliac joints

P

FIG. 8.4  Axial, T1-weighted MRI of ilium and sacroiliac joints.

500

CHAPTER 8   Pelvis Sacroiliac joint

Sacral promontory

Lateral mass of sacrum

A

Ala of ilium

R

L

P

Sacrum

Ilium

FIG. 8.5  Axial CT of sacroiliac joints.

Lateral mass of sacrum

S

Sacroiliac joint

Psoas muscle

Gluteus medius muscle Ilium

Sacral nerves L

R

Sacral foramina Gluteus maximus muscle

Sacrum

I

FIG. 8.6  Coronal, T1-weighted MRI of sacroiliac joints.

The ischial spine projects from the superior ischial ramus between two prominent notches on the posterior surface of the hip bones (Figs. 8.9–8.11 and 8.16). The greater sciatic notch extends from the posterior inferior iliac spine to the ischial spine, and the lesser sciatic notch extends from the ischial spine to the ischial tuberosity

(Figs. 8.9 and 8.10). The two notches are spanned by ligaments that create foramina for the passage of nerves and vessels. The union of the pubic rami and ischium creates a large aperture termed the obturator foramen, which is enclosed by the obturator muscles (Figs. 8.3, 8.9, and 8.11).

CHAPTER 8   Pelvis Lateral mass of sacrum

S

Sacroiliac joint

Ilium

R

L

I

Sacral foramina

FIG. 8.7  Coronal oblique CT of sacroiliac joints.

Sacrum

S

S3

S2

S1

L5

A

S4

S5 Cx1

I

Rectum

FIG. 8.8  Sagittal CT reformat of sacrum and coccyx.

Coccyx

P

501

502

CHAPTER 8   Pelvis Iliac crest S

Posterior superior iliac spine

Anterior superior iliac spine

Ilium

Posterior inferior iliac spine

Ala

Anterior inferior iliac spine Body (of ilium)

P

Acetabulum

Greater sciatic notch A

Body (of ischium)

Superior pubic ramus Ischial spine Obturator foramen

Lesser sciatic notch

Pubis

Superior ischial ramus Ischial tuberosity

Inferior pubic ramus

I

Ischium Inferior ischial ramus

FIG. 8.9  Lateral aspect of right hip bone with divisions. Ala of ilium

S

Sacrum Iliac crest

Greater sciatic notch

Anterior superior iliac spine

Coccyx

Anterior inferior iliac spine P

A

Ischial spine Pubis Lesser sciatic notch

Ischial tuberosity

Greater trochanter of femur

I

Acetabulum

FIG. 8.10  3D CT of hip bone, lateral view.

CHAPTER 8   Pelvis

503

Iliac crest S Ilium

Iliac fossa

Anterior superior iliac spine

Posterior superior iliac spine

Ala

Posterior inferior iliac spine line

Anterior inferior iliac spine

te Arcua

R Body (of ilium)

L Ischial spine

Acetabulum

Superior pubic ramus

Pubis

Ischium Obturator foramen

Inferior pubic ramus I

Inferior ischial ramus

FIG. 8.11  Anterior aspect of right hip bone.

S

Ilium

Arcuate line Pelvic brim

R

L

Pectineal line

Superior pubic ramus

Pubic symphysis

I

FIG. 8.12  Coronal, T1-weighted MRI of pelvis with pelvic brim.

CHAPTER 8   Pelvis

504

S

Iliac crest

Iliacus muscle

Ala of ilium Body of ilium Acetabulum L

R Obturator externus muscle

Ischium

Femur

Obturator internus muscle

Lesser trochanter of femur

Ischial ramus

Adductor brevis muscle I

FIG. 8.13  Coronal, T1-weighted MRI of right hip and acetabulum.

S Iliac crest

Lumbar vertebra

Iliac fossa Body of ilium L

R Acetabulum Greater trochanter of femur

Ischium

Femoral head

I

Pubic bones

FIG. 8.14  Coronal CT reformat of pelvis with acetabulum.

CHAPTER 8   Pelvis

Acetabulum

A

Superior pubic ramus

505

Femoral neck

Greater trochanter

Femoral head

Ischial spine

P

Ischium

FIG. 8.15  Axial CT of acetabulum and superior pubic ramus.

Body of pubic bone

Greater trochanter

A

P

Pubic symphysis

Ischial tuberosity

FIG. 8.16  Axial CT with pubic symphysis.

A

Pubic symphysis

Femur

R

L

Ischial tuberosity

P

Inferior pubic ramus

FIG. 8.17  Axial CT of inferior pubic ramus and ischial tuberosity.

Lesser trochanter

CHAPTER 8   Pelvis

506

Pelvic Inlet and Outlet

the brim is called the true pelvis. The superior aperture or inlet of the true pelvis is measured in the anteroposterior direction from the sacral promontory to the superior margin or crest of the pubic bone. The pelvic outlet or inferior aperture is an opening bounded by the inferior edges of the pelvis and is measured from the tip of the coccyx to the inferior margin of the pubic symphysis in the anteroposterior direction and between the ischial spines in the horizontal direction (Figs. 8.18–8.20).

The pelvis is divided into the false or greater pelvis and the true or lesser pelvis by an oblique plane that extends from the upper anterior margin of the sacrum, along the arcuate line, to the upper margin of the pubic symphysis. The boundary line of this plane is called the pelvic brim, which delineates the boundaries of the abdominal and pelvic cavities (Figs. 8.18 and 8.19). The region above the brim is called the false pelvis, and the region below

Sacral promontory False pelvis

S

Sacrum

True pelvis

Coccyx P

Sacrum False pelvis

Right inferior pubic ramus Pelvic brim

Right superior pubic ramus A

Ischial spine

Arcuate line

Pelvic brim Pelvic inlet A

Superior margin pubic symphysis

P

Pectineal line

A

Coccyx Pelvic inlet A

B

Pelvic outlet R

L

Ischial spine Pelvic outlet

I

Ischial tuberosity

Obturator foramen Ischial spine

C

Coccyx Sacrum

P

Pelvic outlet

FIG. 8.18  Divisions of the pelvis. (A) Superior view. (B) Lateral view. (C) Inferior view. Lumbar spine

P

False pelvis

Sacrum Iliac crest

Iliac fossa

SI joint

Ischial spine R

Pelvic brim

L

Arcuate line

Pelvic outlet Pelvic brim

Pectineal line

Femur

Pubic symphysis

A

FIG. 8.19  3D CT of pelvis, superior view.

CHAPTER 8   Pelvis

507

S

L4 L5 Sacral promontory Sacrum

False pelvis

A

P

Pelvic inlet

Pelvic brim True pelvis Coccyx

Pubis Obturator foramen Pelvic outlet

I

Ischial tuberosity

FIG. 8.20  3D CT of pelvis, lateral view.

MUSCLES Multiple muscles are visualized in the pelvis. For ease of description, the major pelvic muscles have been divided into functional groups: extrapelvic, pelvic wall, and pelvic diaphragm (pelvic floor).

Extrapelvic Muscles Several of the muscles visualized in the pelvis are actually abdominal muscles, such as the rectus abdominis, psoas, and internal and external oblique muscles. The rectus abdominis muscles, visualized on the anterior surface of the abdomen and pelvis, originate from the pubic symphysis and extend to the xiphoid process and the costal cartilage of the fifth, sixth, and seventh ribs. They function to flex the lumbar vertebrae and support the abdomen. The psoas muscles extend along the lateral surfaces of the lumbar vertebrae and act to flex the thigh or trunk. The external and internal oblique muscles are located on the outer lateral portion of the abdomen and span primarily between the cartilages of the lower ribs to the level of the iliac crest. The oblique muscles work together to flex and rotate the vertebral column and compress the abdominal viscera. An inferior band of fibrous connective tissue from the external oblique muscle folds back on itself to form the inguinal ligament, which extends between the anterior superior iliac spine and the

pubic bone (Figs. 8.22, 8.25 and 8.26). Just superior to the inguinal ligament is the inguinal canal, a short (3–6 cm), diagonal tunnel passing through the lower anterior pelvic wall. It has openings at the outer portion called the superficial inguinal ring and the inner portion called the deep inguinal ring. The inguinal canal transmits the spermatic cord in males and the round ligament in females (also see Figs. 7.181-7.187 in Chapter 7). Many of the muscles visualized in the pelvis are considered to be muscles of the hip. The largest of this group are the gluteus muscles (maximus, medius, minimus), which function together to abduct, rotate, and extend the thigh. The largest and most superficial is the gluteus maximus muscle, which makes up the bulk of the buttocks. The gluteus medius and minimus muscles are smaller in size, respectively, and are deep to the gluteus maximus muscle (Figs. 8.21–8.24; also see Chapter 10). Indirect inguinal hernias are protrusions of mesenteric fat and the small intestine at the deep inguinal ring into the inguinal canal. These hernias are five times more common than direct inguinal hernias and seven times more common in males. Indirect inguinal hernias are considered to be a congenital defect of the abdominal wall and are frequently present at birth.

508

CHAPTER 8   Pelvis

S

Gluteus medius muscle

Gluteus minimus muscle L R

I Obturator internus muscle

Gluteus maximus muscle

FIG. 8.21  Posterior view of gluteus muscle group.

Piriformis muscle

Rectus abdominis muscle A

Iliopsoas muscle

Inguinal ligament

Ilium

R

L

Sacrum

P

Gluteus minimus muscle

FIG. 8.22  Axial, T1-weighted MRI of pelvis with gluteus muscle group.

Gluteus medius muscle

Gluteus maximus muscle

CHAPTER 8   Pelvis

Iliopsoas muscle

Piriformis muscle

Sacrum

A

P

Rectus abdominis muscle

Gluteus minimus muscle

Gluteus medius muscle

Ilium

Gluteus maximus muscle

FIG. 8.23  Axial CT of pelvis with gluteus muscle group.

Ilium

S

Obturator internus muscle

Gluteus medius muscle

Gluteus minimus muscle

Gluteus maximus muscle

Obturator externus muscle R

L

Greater trochanter Tensor fasciae latae muscle

I

Acetabulum

FIG. 8.24  Coronal, T1-weighted MRI of pelvis with gluteus muscle group.

509

510

CHAPTER 8   Pelvis

Pelvic Wall Muscles

(Figs. 8.24, 8.25, and 8.30). Inserting on the greater trochanter just below the obturator internus muscle is the obturator externus muscle. This strong muscle originates on the obturator foramen, aiding in adduction and rotation of the thigh (Figs. 8.24, 8.30, and 10.29). Extending from the iliac crest and sacrum is the triangular-shaped iliacus muscle (Figs. 8.26–8.28). As the iliacus muscle spans the iliac fossa, it is joined by the psoas muscle to form the iliopsoas muscle, which extends to insert on the lesser trochanter of the femur (Figs. 8.26, 8.29, and 8.30). The iliopsoas muscle is the most important muscle for flexing the leg, which makes walking possible.

The muscles of the pelvic wall include the piriformis, obturator internus and externus, and iliacus muscles (Figs. 8.21–8.30 and Table 8.1; also see Chapter 10). The piriformis muscle, which acts to rotate the thigh laterally, originates from the ilium and sacrum and passes through the greater sciatic notch to insert on the greater trochanter of the femur (Figs. 8.22, 8.23, and 8.25). The fanshaped obturator internus muscle also functions as a lateral thigh rotator. It extends from the pubic bone and obturator foramen to pass through the lesser sciatic notch and attaches to the greater trochanter of the femur

Inguinal ligament

Pubic symphysis A

Pubic tubercle Obturator canal Anterior superior iliac spine

Ischial spine

Greater sciatic notch

R

L

Obturator internus muscle Iliac crest

Iliacus muscle (cut)

Femoral nerve

Psoas major muscle (cut)

Piriformis muscle

P Sacrum

FIG. 8.25  Pelvic cavity, superior view.

S

Psoas muscle

Sacrum Iliac crest Greater sciatic notch

Iliacus muscle R

L

Inguinal ligament

Coccyx

Greater trochanter

Iliopsoas muscle

Pectineus muscle

Adductor minimus muscle

Sartorius muscle

Adductor magnus muscle I

FIG. 8.26  Anterior view of pelvic muscles.

Adductor longus muscle

CHAPTER 8   Pelvis Rectus abdominis muscle

Psoas muscle

A

Iliac crest Gluteus medius muscle

Iliacus muscle L

R Ilium

Gluteus maximus muscle

Sacrum

P

Sacroiliac joint

FIG. 8.27  Axial, T1-weighted MRI of ilium and sacroiliac joints.

Iliacus muscle

Rectus abdominis muscle

A

Iliac crest Gluteus medius muscle R

L

Gluteus maximus muscle

Psoas muscle

P

FIG. 8.28  Axial CT of pelvis with iliacus muscle.

511

CHAPTER 8   Pelvis

512

Rectus femoris muscle

Sartorius muscle

A

Iliopsoas muscle

Femoral artery

Tensor fasciae latae muscle

Femoral vein

Gluteus medius muscle

Ilium

Femoral head

Acetabulum

R

L Obturator internus muscle

Obturator internus tendon Ischium

Gluteus maximus muscle P

FIG. 8.29  Axial, T1-weighted MRI of right hip with iliopsoas muscle.

Iliopsoas muscle

Pectineus muscle

A

Prostate

Sartorius muscle

Rectus femoris muscle Tensor fasciae latae muscle Gluteus medius muscle

R

L

Quadratus femoris muscle

Gluteus maximus muscle

Ischium

P

Obturator internus muscle

Obturator externus muscle

FIG. 8.30  Axial CT of male pelvis with iliopsoas muscle.

Femur

CHAPTER 8   Pelvis TABLE 8.1

513

Muscles of the Pelvic Wall and Diaphragm

Muscle

Origin

Insertion

Function

Piriformis Obturator internus

Ilium and sacrum Obturator foramen and pubic bone

Laterally rotates and adducts thigh Laterally rotates thigh

Obturator externus

Obturator foramen

Iliacus

Iliac crest and sacrum

Levator ani

Symphysis pubis and ischial spine

Greater trochanter of femur Greater trochanter of femur (medial surface) Greater trochanter of femur (trochanteric fossa) Lesser trochanter of femur (tendon fused with that of psoas muscle) Coccyx

Coccygeus

Ischial spine

Sacrum and coccyx

Pelvic Diaphragm (Pelvic Floor) Muscles The funnel-shaped pelvic diaphragm, also called the pelvic floor, is a layer of muscles and fascia that forms the greatest majority of the floor of the pelvis. The primary muscles of the pelvic diaphragm are the levator ani and coccygeus muscles. The levator ani muscles are the largest and most important muscles of the pelvic diaphragm, originating from the symphysis pubis and ischial spines to form winglike arches that attach to the coccyx. The

Laterally rotates and adducts thigh Flexes hip Supports pelvic viscera, flexes coccyx, elevates and retracts anus Assists in supporting the pelvic floor and flexes coccyx

levator ani muscles can be subdivided into three parts according to their attachments and the pelvic viscera they are associated with: the pubococcygeus, puborectalis, and iliococcygeus muscles. The two coccygeus muscles form the posterior portion of the pelvic diaphragm, arising from the ischial spines and fanning out to attach to the lower sacrum and coccyx. Together, the levator ani and coccygeus muscles provide support for the pelvic contents (Figs. 8.31–8.39 and Table 8.1).

A Pubis Urethra

Puborectalis muscle Pubococcygeus muscle

Vagina

Iliococcygeus muscle

Ischium R

L

Ischial tuberosity Obturator internus muscle

Rectum Coccygeus muscle

Tendon of obturator internus muscle Coccyx Sacrum

P

FIG. 8.31  Inferior view of pelvic diaphragm muscles, female pelvis.

Levator ani muscle

CHAPTER 8   Pelvis

514

Pectineus muscle

A

Femoral artery

Spermatic cord

Femoral vein

Prostate Obturator canal

Superior pubic ramus

Femoral head

Acetabulum R

L Obturator internus muscle

Levator ani muscle (puborectalis muscle)

Rectum Ischioanal fossa

Coccygeus muscle

Sacrotuberous ligament P

Coccyx

FIG. 8.32  Axial, T1-weighted MRI of male pelvis with coccygeus muscle.

Obturator internus muscle A

Rectum

Iliopsoas muscle

Sartorius muscle

Gluteus medius muscle

R

L Femoral head Acetabulum

Gluteus maximus muscle

Coccygeus muscle

P

Coccyx

FIG. 8.33  Axial CT of pelvis with coccygeus muscle.

Gluteus maximus muscle

CHAPTER 8   Pelvis

A

Puboprostatic ligament

Pubic symphysis

Pectineus muscle

Prostatic urethra

Obturator externus muscle

Prostate R

L Obturator internus muscle

Levator ani muscle (puborectalis muscle)

Ischioanal fossa

Anus

Ischium Gluteus maximus muscle P

FIG. 8.34  Axial, T2-weighted MRI of male pelvis with levator ani muscles.

Pubovesical ligament

A

Retropubic space

Pectineus muscle

Femoral vein Femoral artery

Obturator externus muscle

Urethra

R

L

Obturator internus muscle

Vagina Anus Ischioanal fossa

Levator ani muscle

Ischium P

FIG. 8.35  Axial, T2-weighted MRI of female pelvis with levator ani muscles.

515

CHAPTER 8   Pelvis

516

S

Fundus of uterus

Uterine cavity

Cervix Anterior fornix

Posterior fornix

A

P Coccyx

Bladder

Levator ani muscle

Retropubic space

External anal sphincter

Pubic symphysis

Rectum Vagina

Perineal body I

FIG. 8.36  Sagittal, T2-weighted MRI of female pelvis with pelvic diaphragm muscles.

S

Seminal vesicle

Bladder

Rectum

Pubic symphysis

Prostate

A

P Levator ani muscle

Membranous urethra

Perineal membrane

Corpus cavernosum

Penile urethra

Corpus spongiosum I

FIG. 8.37  Sagittal, T2-weighted MRI of male pelvis with perineal membrane.

CHAPTER 8   Pelvis

517

S Ureteral Trigone openings

Ureter

Bladder

R

L Obturator internus muscle

Prostate gland

Ischium Levator ani muscle

Penineal membrane

Urethra I

FIG. 8.38  Coronal view of levator ani muscles and perineal membrane.

Sacrum

S

Piriformis muscle

Obturator internus muscle

R

L

Rectum

I

Levator ani muscle

FIG. 8.39  Coronal, T1-weighted MRI of pelvis with levator ani muscles.

Ischium

518

CHAPTER 8   Pelvis of fascia, called the perineal membrane, stretching between the pubic arches. Located at the center of the midpoint between the ischial tuberosities is the perineal body, a mass of muscle and fascia that is the site where the interlacing fibers of several muscles converge. In females, the perineal body is located between the vagina and rectum, and in males, it is located between the rectum and root of the penis (Fig. 8.40).

Perineum The perineum is the area located posterior to the pubic arches and anterior to the coccyx. The bony circumferential boundaries of the perineum are the inner edges of the pelvic outlet and consist of the following surface relationships: anteriorly by the pubic symphysis; laterally by the pubic rami, ischial rami, ischial tuberosities, and sacrotuberous ligaments; and posteriorly by the coccyx (Fig. 8.40). The region is divided into two triangles, posterior and anterior, by an imaginary line joining the ischial tuberosities. The posterior triangle is the anal triangle, and the anterior triangle is the urogenital triangle. The anal triangle contains the inferior one-third of the anal canal and its sphincter muscles, as well as the ischioanal fossa (Figs. 8.34, 8.35, 8.40, and 8.42). The urogenital triangle contains the openings of the urethra and vagina in the female and the urethra and root structures of the penis in the male (Figs. 8.40–8.42). It is covered by a tough layer

Pubic symphysis

The perineal body is an important structure in females because of its function as a support for the pelvic organs. When muscles connected to the perineal body stretch or tear (i.e., during childbirth), the muscular support of the pelvic floor can be compromised, resulting in prolapse of the pelvic organs. Injury to the perineal body due to trauma or infection can result in the formation of a fistula.

A

Urogenital triangle

Perineal body

Scrotum Median raphe

R

L

Superficial transverse perineal muscle

Bulbospongiosus muscle (root of penis) Left pubic arch Ischioanal fossa Ischial tuberosity

Anal triangle Anus Right pubic arch

Sacrotuberous ligament

P Coccyx

Sacrum

Pubic symphysis Urethra

A

Vagina

Urogenital triangle

L Ischial tuberosity

Superficial transverse perineal muscle

R

Ischioanal fossa Sacrotuberous ligament

Perineal body P Anal triangle

Coccyx

Anus Sacrum

External anal sphincter muscle

FIG. 8.40  Boundaries of the perineum. Top, Male. Bottom, Female.

CHAPTER 8   Pelvis

Urogenital triangle of perineum

Pubic symphysis

A

Pubic bone

519

Prostate gland

R

L

Rectum

Coccyx

P

Anal triangle of perineum

Ischial tuberosity

FIG. 8.41  Axial CT with boundaries of male perineum.

Obturator externus muscle

Pectineus Pubic muscle bone

A

Pubic symphysis

Bladder

R

Urogenital triangle of perineum

L Ischium Ischioanal fossa

Obturator internus muscle

Rectum

P

Coccyx

Vagina

FIG. 8.42  Axial CT with boundaries of female perineum.

Anal triangle of perineum

CHAPTER 8   Pelvis

520

narrowing called the neck of the bladder, which is continuous with the urethra (Fig. 8.43). The bladder neck contains the muscular internal urethral sphincter, which provides for involuntary control over the release of urine from the bladder. Three openings in the floor of the bladder form a triangular area called the trigone. Two of the openings are created by the ureters (Fig. 8.38). The third opening is located in the apex of the trigone and is formed by the entrance to the urethra (Figs. 8.38, 8.43–8.47, and 8.52). The pelvic portions of the ureters run anterior to the internal iliac arteries and enter the posterolateral surface of the bladder at an oblique angle (Figs. 8.49 and 8.51). The bladder is anchored to the pelvis by peritoneal ligaments. The apex is attached to the anterior abdominal wall by the median umbilical ligament, which is the remnant of the fetal urachus (obliterated umbilical artery). Two medial umbilical ligaments from the body of the bladder ascend along with the median umbilical ligament to the umbilicus (Fig. 8.48). The fibrous cords of these ligaments represent the obliterated remains of the two umbilical arteries, which provided blood to the

VISCERA The pelvic cavity contains the bladder, rectum, and internal reproductive organs.

Bladder The bladder is a pyramid-shaped muscular organ that rests on the pelvic floor, immediately posterior to the pubic symphysis (Figs. 8.43–8.51). It functions as a temporary reservoir for the storage of urine. In a normal adult, it takes approximately 200 to 250 mL of urine to accumulate before the urge to urinate is triggered. However, the bladder has the potential storage capacity of approximately 750 mL. The superior body of the bladder is covered by peritoneum, allowing loops of ileum and sigmoid colon to rest on it. The posterior aspect is referred to as the fundus or base of the bladder. The base is closely related to the anterior wall of the vagina in the female and to the rectum in the male. Facing toward the pubic symphysis is the apex of the bladder. The inferior portion is a funnel-shaped

S

Uterine (fallopian) tube Ovary Median umbilical ligament Superior surface of bladder

Sacral flexure Uterus

Bladder

P Cervix

Apex of bladder A Pubic symphysis

Base of bladder

Neck of the bladder

Rectum

Perineal membrane Clitoris

Vagina

Labia minora Anus

Labia majora

Urethra I

FIG. 8.43  Sagittal view of female pelvis.

CHAPTER 8   Pelvis placenta during fetal development. The bladder neck is held in place by the puboprostatic ligament in males and the pubovesical ligament in females. The urethra is a muscular tube that drains urine from the bladder. In both genders, the urethra passes through the perineal membrane, which contains the external urethral sphincter muscle responsible for the voluntary closure of the bladder. The short (3–4 cm) female urethra is located in front of the anterior vaginal wall and descends inferiorly and anteriorly to terminate at the external urethral opening located between the clitoris and vagina (Figs. 8.43, 8.44, and 8.52). The male urethra is much longer (18–20 cm) and extends from the inferior

portion of the bladder to the tip of the penis (Figs. 8.45, 8.46, and 8.53). It can be subdivided into three regions: prostatic urethra, membranous urethra, and penile urethra. The prostatic urethra passes through the middle of the prostate gland. The membranous urethra is the shortest and narrowest portion of the urethra and is the portion that penetrates the perineal membrane. The penile urethra is the longest portion, extending from the external urethral sphincter to the tip of the penis (Figs. 8.45 and 8.46). The male urethra has the dual function to drain urine from the bladder and to receive secretions from the prostatic and ejaculatory ducts and the ducts of the bulbourethral glands.

S

Rectouterine pouch Rectum A

P

Median umbilical ligament

Vagina

Apex of bladder

Urethra

Bladder

Pubic symphysis

I

521

Uterus

FIG. 8.44  Sagittal, T2-weighted MRI of female pelvis.

522

CHAPTER 8   Pelvis Retropubic space S

Ureter Base of the bladder

Bladder Apex of bladder

Seminal vesicle

Pubic bone Vas deferens Prostate

Neck of bladder P A

Rectum Prostatic urethra

Ejaculatory duct

Perineal membrane

Membranous urethra

Penile urethra

Anus Bulbourethral gland Epididymis

Penis

Bulbospongiosus muscle

Testis Scrotum I

FIG. 8.45  Sagittal view of male pelvis.

Seminal vesicle

S

Sacrum

Bladder

Coccyx A

P

Pubic symphysis

Prostate Prostatic urethra Rectum

Corpus cavernosum

Perineal membrane

Corpus spongiosum I

Penile urethra

Root of penis

FIG. 8.46  Sagittal, T2-weighted MRI of male pelvis.

CHAPTER 8   Pelvis

523

S

Uterus R

L

Obturator internus muscle

Ovary

Obturator externus muscle

Bladder

Perineal membrane

I

FIG. 8.47  Coronal, T2-weighted MRI of female pelvis with bladder.

S

Umbilicus Left medial umbilical ligament

Median umbilical ligament

Peritoneum Right inferior epigastric artery

Ilium Left femoral nerve

Right external iliac artery R

L

Right external iliac vein

Left vas deferens

Apex of bladder Left ureter

Right vas deferens

Right ureter

Left seminal vesicle I

FIG. 8.48  Coronal view of bladder and ligaments in male pelvis.

CHAPTER 8   Pelvis

524

Lateral mass of sacrum

Left ureter

Left renal pelvis S

Left kidney

L5

Right ureter

Bladder

I

Superior pubic ramus

FIG. 8.49  3D CT urogram.

CHAPTER 8   Pelvis Base of bladder

Uterus

A

525

Bladder

R

L

P

Rectum

Ovary

Follicle

FIG. 8.50  Axial, T2-weighted MRI of female pelvis with bladder.

Base of bladder

Rectus abdominis muscle

Seminal vesicle A

R

L

P Ureters

FIG. 8.51  Axial CT of male pelvis with bladder.

Rectum

CHAPTER 8   Pelvis

526

Retropubic space

Pubic symphysis

A

Rectus abdominis muscle

Pectineus muscle

Urethra

Femoral vein Femoral nerve

Vagina

Femoral artery R

L Obturator externus muscle

Levator ani muscle

Ischial tuberosity

Rectum

Obturator internus muscle

P

FIG. 8.52  Axial, T1-weighted MRI of female pelvis with urethra.

Body of pubis

Pubic symphysis

Prostate gland

A

Prostatic urethra Femoral vein

Pectineus muscle

Femoral artery Femur R

L

Ischium

Levator ani muscle

Rectum

P

Coccyx

Obturator internus muscle

FIG. 8.53  Axial CT of male pelvis with urethra.

CHAPTER 8   Pelvis

527

S

Rectum The rectum is the terminal part of the large intestine extending from S3 to the tip of the coccyx; it is approximately 15 cm long. It follows the anteroposterior curve of the sacrum and coccyx (sacral flexure) and ends by turning inferiorly and anteriorly (perineal flexure) to become the anal canal, which ends at the anus (Figs. 8.43–8.46 and 8.54–8.57). Between the two flexures is a fold of tissue called the transverse rectal fold (Kohlrausch’s fold) located 5 to 8 cm from the anus (Fig. 8.54). It serves as a topographic landmark during a rectal examination marking the posterior side of the prostate in males and the vault of the vagina in females. The upper third of the rectum, the rectal ampulla, has considerable distensibility. As fecal material collects in this area, it triggers the urge to defecate. The anal canal is the distal portion of the rectum and contains small longitudinal folds called rectal or anal columns. The anus marks the exit of the anal canal and is under the involuntary control of the internal anal sphincter, a circular muscle layer within the rectal wall. The external anal sphincter consists of a ring of skeletal muscle fibers and is under voluntary control (Figs. 8.40, 8.43, 8.45, and 8.54–8.57).

Sigmoid colon

Ampulla Levator ani muscle

Kohlrausch’s fold R

L

Internal sphincter muscle External sphincter muscle

I Anal canal

FIG. 8.54  Coronal view of rectum.

S

Bladder Ilium

Seminal vesicle

Prostate R

L Levator ani muscle Rectum

Obturator internus muscle

Ischium

External anal sphincter

Rectal column

I

FIG. 8.55  Coronal, T2-weighted MRI of male pelvis with rectum.

CHAPTER 8   Pelvis

528

Pectineus muscle

A

Pubic symphysis

Great saphenous vein Superficial femoral artery Deep femoral artery Urethra

Obturator externus muscle

Vagina

R

L

Obturator internus muscle

Ischial tuberosity

Levator ani muscle

Rectum

P

FIG. 8.56  Axial, T2-weighted MRI of female pelvis with rectum.

Femoral artery

Femoral vein

A

Rectus abdominis muscle

Bladder

Femoral head

R

L Gluteus maximus muscle

P Rectum FIG. 8.57  Axial CT of female pelvis with rectum.

Vagina

CHAPTER 8   Pelvis

529

Uterus.  The uterus is a pear-shaped muscular organ

Female Reproductive Organs The female reproductive system is responsible for producing sex hormones and ova and functions to protect and support a developing embryo. The principal organs of the female reproductive system are located within the pelvic cavity and include the uterus, ovaries, uterine tubes, and vagina (Figs. 8.58–8.60).

located in the pelvic cavity between the bladder and the rectum (Figs. 8.58 and 8.59). The uterus can be sub­ divided into two anatomic regions: body and cervix. The body is the largest division, comprising the upper twothirds of the uterus. The rounded superior portion of the body is called the fundus, which is located just superior to the region where the uterine tubes enter the uterus. S

Uterine (fallopian) tube Ovary

Body of uterus

Fundus of uterus

Rectouterine pouch

Vesicouterine pouch

Posterior fornix of vagina

Bladder A Pubic symphysis

Cervix

Retropubic space

Rectum

P Anterior fornix of vagina

Perineal membrane

Vagina Urethra

Clitoris Labia minora

External anal sphincter Anus

Labia majora

FIG. 8.58  Sagittal view of female pelvis.

I

Body of uterus

S

Endometrium

Perimetrium

Rectouterine pouch Cervix

Uterine cavity A

P Vesicouterine pouch

Fundus of uterus

Vagina Myometrium Urethra Bladder

Pubic Retropubic symphysis space

I

FIG. 8.59  Sagittal, T2-weighted MRI of female reproductive system.

530

CHAPTER 8   Pelvis

The lateral borders of the fundus contain the cornua, where the uterine tubes attach to the uterus. The narrow inferior third of the uterus is called the cervix, which communicates with the vagina. The narrow lumen within the cervix, called the cervical canal, is a conduit between the uterine cavity superiorly via the internal os and opens inferiorly into the vagina via the external os (Fig. 8.60). The most common position of the uterus is with the body projecting superiorly and anteriorly over the bladder, with the fundus adjacent to the anterior abdominal wall and the cervix directed inferiorly and posteriorly into the upper end of the vagina or vaginal vault (Figs. 8.47 and 8.59). The wall of the uterus is composed of three layers: the endometrium is the inner

glandular tissue lining the inner wall and responds to cyclic ovarian hormone changes; the myometrium is the middle, muscular layer and the thickest component of the uterine wall; and the perimetrium is the outer layer, consisting of a serous membrane that covers the fundus and posterior surface of the uterus (Figs. 8.59 and 8.60). The endometrium is lined by a mucous membrane that is continuous with the inner lining of the vagina and uterine tubes. The thick myometrial layer is highly vascular and is responsible for the main contractive force during childbirth. The perimetrium is formed by peritoneum and is firmly attached to the myometrium. The uterus is the reproductive organ responsible for protecting the fetus during development (Figs. 8.58–8.63). S

Uterine tube

Suspensory ligament of ovary

Myometrium

Endometrium

Fundus Perimetrium

Infundibulum Cornua

Ovarian ligament

Fimbriae R

Ovary

Body of uterus

Ovarian ligament

L

Ureter Broad ligament

Uterine cavity

Cervical canal

Internal os

Fornix (vaginal vault)

Cervix

Vagina

External (cervical) os I

FIG. 8.60  Anterior view of uterus.

S Broad ligament Fundus of uterus

Obturator internus muscle

Ovary R

L

Vagina Obturator externus muscle I

FIG. 8.61  Coronal, T1-weighted MRI of female pelvis.

CHAPTER 8   Pelvis

Bladder

A

Round ligament

L

R

Ovary

Body of uterus

P

Uterine cavity

Myometrium

FIG. 8.62  Axial, T2-weighted MRI of female pelvis with body of uterus.

Round ligament

Uterine cavity

A

R

L

Myometrium

P

Rectum

Vagina

FIG. 8.63  Axial CT of female pelvis with body of uterus.

531

CHAPTER 8   Pelvis

532

Suspensory Ligaments of the Uterus.  The uterus

sacrum, preventing forward movement of the uterus (Figs. 8.64–8.66). The lateral cervical (cardinal) ligaments are located at the base of the broad ligament and extend like a fan from the lateral walls of the cervix and vagina to anchor into the fascia of the obturator internus muscle and pelvic wall. They help suspend the uterus above the bladder and prevent downward displacement of the uterus (Figs. 8.65, 8.67, and 8.68). Additional support is provided by the muscles and fascia of the pelvic floor.

is stabilized by several pairs of suspensory ligaments formed by the peritoneum. The round ligaments extend laterally from the uterine cornua, through the inguinal canal, and anchor to the labia majora (Figs. 8.62–8.65). They help keep the uterine body flexed anteriorly (anteversion) and help prevent posterior movement of the uterus. The uterosacral ligaments extend from the lateral walls of the cervix and course posteriorly around the rectum to anchor to the anterior surface of the

S Ovary

Ureter

Rectouterine pouch

Rectum

Uterosacral ligament

Suspensory ligament of ovary

Broad ligament Uterine tube

Uterus L

R

Round ligament

Ovarian ligament

Deep inguinal ring Inferior epigastric artery

Medial umbilical ligament

I

Median umbilical ligament

Urinary bladder

FIG. 8.64  Anterior view of female pelvis with peritoneal ligaments.

CHAPTER 8   Pelvis A Bladder

Vesicouterine pouch

Uretus

Round ligament

Ovarian ligament Broad ligament

Uterine tube R

L Cervix

Ovary

Rectouterine pouch

Lateral cervical (cardinal) ligament

Suspensory ligament

Infundibulum

Rectum Ureter

Fimbriae

Uterosacral ligament

P

FIG. 8.65  Superior view of female pelvis with peritoneal ligaments.

A

Bladder

Uterus

R

L

Uterosacral ligament

P

Rectum

Rectouterine pouch

FIG. 8.66  Axial, T2-weighted MRI of female pelvis with uterosacral ligaments.

533

534

CHAPTER 8   Pelvis A

Bladder

R

L

Lateral cervical (cardinal) ligament

Rectum

P

Cervix

Vesicouterine pouch

FIG. 8.67  Axial, T2-weighted MRI of female pelvis with lateral cervical (cardinal) ligaments.

Uterus

A

Bladder

R

L

Lateral cervical (cardinal) ligament

P

Rectum

FIG. 8.68  Axial CT of female pelvis with lateral cervical (cardinal) ligaments.

CHAPTER 8   Pelvis

Ovaries.  The paired ovaries are small almond-shaped

organs located on either side of the uterus (Figs. 8.60–8.62, 8.64, 8.65, and 8.69–8.73). They lie in a depression on the lateral walls of the pelvis and are held in place by the ovarian and suspensory ligaments (Fig. 8.65). The cordlike ovarian ligaments attach the inferior aspect of the ovaries to the lateral surface of the uterus and uterine tubes (Figs. 8.60, 8.64, 8.65, and 8.69). The suspensory ligament attaches the superior aspect of the ovaries to the lateral sides of the pelvic wall and contains the ovarian vessels (Figs. 8.60, 8.64, 8.65, and 8.69). The ovaries are responsible for the production of ova and the production and secretion of estrogens and progeste­rone. Estrogens are responsible for the development and maintenance of female characteristics and reproductive organs. Progesterone is responsible for the uterine changes in preparation for pregnancy, such as the thickening of the uterine lining and decreasing the contractions of the uterine muscles. A follicular cyst represents the mature oocyte and its surrounding follicular cavity. Fluid increases within the cavity as the oocyte matures. A follicular cyst occurs when the graafian follicle fails to rupture and release its egg. They generally resolve spontaneously after two or three menstrual cycles.

Uterine Tubes.  The uterine (fallopian) tubes are

slender, muscular tubes (approximately 8–20 cm long) extending laterally from the body of the uterus to the peritoneum near the ovaries (Figs. 8.60, 8.64, and 8.65). They are supported by the broad ligament and at their distal end expand to form a funnel-shaped infundibulum. The infundibulum has numerous 1- to 2-cm fingerlike projections called fimbriae, which spread loosely over the surface of the ovaries (Figs. 8.60 and 8.65). During ovulation, the fimbriae trap the ovum and sweep it into the uterine tubes for transport to the uterus. The proximal portion of the uterine tubes open into the uterus at the cornua, and the distal portion opens directly into the peritoneal cavity, immediately superior to the ovaries, thereby providing a direct route for pathogens to enter the pelvic cavity.

Vagina.  The vagina is an 8- to 10-cm muscular tube

extending anteroinferiorly from the cervix of the uterus to the external vaginal orifice. The vaginal vault or fornix is the expanded upper vaginal area that surrounds the cervical os like a ring and is commonly divided into anterior and posterior fornices. The vagina is located between the bladder and the rectum and functions as a receptacle for sperm and as the lower portion of the birth canal (Figs. 8.57–8.61 and 8.72–8.75).

S

Perimetrium Suspensory ligament of ovary

Myometrium Endometrium Ovary

Ovary Broad ligament R

Ovarian ligament L Uterine cavity

Obturator internus muscle

Bladder

Urethra

Levator ani muscle

535

I

FIG. 8.69  Coronal, T2-weighted MRI of female pelvis.

536

CHAPTER 8   Pelvis A

Bladder

R

L

Myometrium

Body of uterus

P

Uterine cavity

Ovary

FIG. 8.70  Axial, T2-weighted MRI of female pelvis with ovaries.

Uterus

A

Rectum

Round ligament

L

R

P

Ovaries

FIG. 8.71  Axial CT of female pelvis with ovaries.

CHAPTER 8   Pelvis Obturator internus muscle Ovary

Uterus

S

Broad ligament

R

L

Obturator externus muscle

Perineal membrane

I

Vagina

Levator ani muscle

FIG. 8.72  Coronal, T2-weighted MRI of female pelvis with ovaries. S

Psoas muscle Left common iliac vein R

L

Sigmoid colon

Iliacus muscle

Uterus Ovarian ligament Right ovary

Bladder

I

Vagina

Pubis

FIG. 8.73  Coronal CT reformat of female pelvis with ovaries.

537

CHAPTER 8   Pelvis

538

Bladder

Vagina

A

Femur R

L

P

Rectum

Obturator internus muscle FIG. 8.74  Axial, T2-weighted MRI of female pelvis with vagina.

Femoral vein

Femoral artery

A

Femur Acetabulum R

L

Bladder

Rectum

P

FIG. 8.75  Axial CT of female pelvis with vagina.

Vagina

CHAPTER 8   Pelvis

Pelvic Spaces.  A peritoneal fold called the broad

Anterior

ligament encloses the ovaries, uterine tubes, and uterus (Figs. 8.64, 8.65, 8.69, and 8.72). The broad ligament extends from the sides of the uterus to the walls and floor of the pelvis, preventing side-to-side movement of the uterus and dividing the pelvis into anterior and posterior pouches. The anterior vesicouterine pouch is located between the uterus and the posterior wall of the bladder, whereas the posterior rectouterine pouch (pouch of Douglas) lies between the uterus and rectum (Figs. 8.58, 8.76, and 8.77). In males, the peritoneum is reflected from the rectum over the seminal vesicles and bladder to create the rectovesical pouch, located between the rectum and bladder (Figs. 8.79 and 8.80). The pelvic spaces are common areas for the accumulation of fluid within the pelvis. Another space in the pelvis is the retropubic space, which is located between the pubic bones and the bladder and contains extraperitoneal fat and connective tissue for the expansion of the bladder (Figs. 8.77, 8.78, and 8.80).

Iliopsoas Ilium muscle

External iliac artery

External iliac Round vein ligament A

539

Pubic symphysis Urinary bladder

Retropubic space (opened)

Cervix

Pubovesical ligament Vesical fascia Vesicouterine pouch R

L

Lateral cervical ligament Rectouterine pouch Rectal fascia Rectum Uterosacral ligament Presacral space (opened) Posterior

FIG. 8.77  Superior view of pelvic spaces, female.

Uterus

Lymph nodes

Pectineus Retropubic muscle space

A

Pubic symphysis

Pubis Urethra

Vagina Femoral vein Femoral artery

R

L L

R

Rectouterine pouch Rectum Ischium

Gluteus medius muscle

Gluteus maximus muscle

P

Piriformis Ovary Ovarian muscle ligament

FIG. 8.76  Axial, T2-weighted MRI of female pelvis with ovarian ligament.

Obturator internus muscle

P

Levator ani muscle

Rectum

FIG. 8.78  Axial, T2-weighted MRI of female pelvis with retropubic

space.

540

CHAPTER 8   Pelvis

Scrotum.  The scrotum is a musculotendinous pouch that encloses the testis, epididymis, and lower portions of the spermatic cord (Figs. 8.79–8.81). It is composed of three fascial layers and a connective tissue layer embedded with smooth muscle fibers called the dartos tunica. Internally, the dartos tunica forms a septum that divides the scrotum into right and left

Male Reproductive Organs The principal structures of the male reproductive system are the testis, epididymis, vas deferens, ejaculatory duct, seminal vesicle, prostate gland, bulbourethral gland, and penis. All these structures, except the testes and penis, are located within the pelvic cavity (Figs. 8.79 and 8.80).

S

Ureter Rectovesical pouch

Bladder

Seminal vesicle

Pubic bone Vas deferens Prostate

Rectum P

A

Prostatic urethra Ejaculatory duct

Membranous urethra

Penile urethra

Bulbourethral gland Epididymis

Penis

Testis Scrotum I

FIG. 8.79  Sagittal view of male pelvis.

Bladder

Seminal vesicle

S

Retropubic space

Rectovesical pouch

Rectum

Sacrum

Pubic symphysis Prostate

Corpus cavernosum A

P Levator ani muscle

Corpus spongiosum

Perineal membrane

Testis

Scrotum

I

FIG. 8.80  Sagittal, T2-weighted MRI of male reproductive system.

CHAPTER 8   Pelvis compartments (median raphe), each containing a testis (Figs. 8.81 and 8.82). The scrotum facilitates sperm formation by distending the testes outside the peritoneum in a cooler environment, in effect regulating the

temperature of the testes. In cold temperatures, the dartos tunica responds by constricting and pulling the testis closer to the body. This gives the scrotum its wrinkled appearance.

S Testicular vein Right ureter

Testicular artery

Bladder

Inguinal ligament

Inguinal canal

Superficial ring of inguinal canal Penis L Spermatic cord

R Vas deferens Spermatic cord Pampiniform plexus

Scrotal septum (median raphe)

Testicular artery

Cremaster muscle Dartos tunica muscle

Head of epididymis Testis (covered by visceral layer of tunica vaginalis)

Scrotal skin (cut) I Raphe

FIG. 8.81  Coronal view of male reproductive system.

S

Spermatic cord

Inguinal canal

Corpora cavernosa L

R Inguinal lymph node

Corpus spongiosum Pampiniform plexus Head of epididymis

Median raphe

Testes

Scrotum

541

I

FIG. 8.82  Coronal, T1-weighted MRI of male reproductive system.

542

CHAPTER 8   Pelvis

Testes and Epididymis.  The paired testes are sus-

their respective lobule and converge in an area called the rete testis. From here, about 15 to 20 ductules leave the rete testis to enter the head of the epididymis (Fig. 8.83). The epididymis is a tightly coiled tubular structure located on the superoposterior surface of each testis. The head of the epididymis is located on the upper pole of each testis, whereas the body courses along the posterior surface to the tail, which is located under the lower pole of each testis. Sperm are transmitted from the testis to the epididymis, where they are stored as they undergo the final stages of maturation (Figs. 8.79 and 8.81–8.87).

pended in the fleshy, pouchlike scrotal sacs by the spermatic cords. Each testis is an ovoid organ that produces sperm and the male sex hormone, testoste­ rone (Figs. 8.83 and 8.84). The outer fibrous covering of the testes is the tunica albuginea, which also projects into each organ to create wedge-shaped lobules. Each testis is made up of several hundred lobules, with each lobule containing 1 to 4 seminiferous tubules, approximately 800 seminiferous tubules in total. This is where spermatogenesis occurs. The seminiferous tubules leave

Pampiniform plexus

Ductus deferens

Epididymis

Efferent ducts

Head Body Tail

Rete testis

Seminiferous tubules Tunica albuginea Lobule

Septum

FIG. 8.83  Sagittal view of testis. S

Bladder Rectum A

P

Pubic symphysis Penis Epididymis

Testes

I

Prostate

FIG. 8.84  Sagittal, T1-weighted MRI of male pelvis with testes.

CHAPTER 8   Pelvis S

Head of epididymis R

L

Testes

Median raphe

Scrotum I

FIG. 8.85  Coronal, T2-weighted MRI of male pelvis with testes. Testis Sartorius muscle

A

Median raphe

Epididymis Adductor longus muscle

Great saphenous vein

Gracilis muscle

Femoral artery, vein and nerve

L

R

Adductor brevis muscle

Adductor magnus muscle

Semitendinosus muscle P

FIG. 8.86  Axial, T2-weighted MRI of male pelvis with testes. Sartorius muscle

Femoral artery

Testes

A

Scrotum

Epididymis

Femoral vein

Adductor longus muscle

Rectus femoris muscle

Adductor magnus muscle

Vastus intermedius muscle

Femur Vastus lateralis muscle

Gluteus maximus muscle

P

FIG. 8.87  Axial CT of male pelvis with testes.

543

544

CHAPTER 8   Pelvis

Vas Deferens (Ductus) and Ejaculatory Duct.  As

connective tissue and muscle of the paired spermatic cords (Fig. 8.81).

a continuation from the tail of the epididymis, the vas deferens is a long muscular tube that ascends in the posterior portion of the spermatic cord and traverses the inguinal canal, exiting at the deep inguinal ring (Figs. 8.81 and 8.88). It then leaves the spermatic cord and passes along the lateral pelvic wall over the ureter to the posterior surface of the bladder, where it broadens and becomes the ampulla of the vas deferens. Near its proximal end, it joins with the duct of the seminal vesicle to form the ejaculatory duct, which empties into the prostatic urethra. Each vas deferens, along with a testicular artery and vein, is surrounded by the tough

Spermatic Cords.  The spermatic cords begin at the

deep inguinal ring, extend through the inguinal canal, and exit via the superficial inguinal ring to suspend the testes in the scrotum (Figs. 8.81, 8.82, and 8.89–8.92). Within the spermatic cord is the pampiniform plexus, a group of interconnected veins that drain the blood from the testicles (Figs. 8.81 and 8.83). The pampiniform plexus cools the blood in the testicular artery before it enters the testes, helping to maintain a temperature that is conducive for optimal sperm production.

S Body of bladder

Vas deferens Ureter Peritoneum, cut margin and lower surface Fundus of urinary bladder

Prostate

Right seminal vesicle

Membranous urethra

Ampulla of vas deferens

Bulbourethral (Cowper) gland

Ejaculatory duct of seminal vesicle

R

Bulb of penis Crus of penis

L

Corpora cavernosa Vas deferens

Corpus spongiosum

Head Body Glans penis External urethral opening I

Tail Testis

FIG. 8.88  Posterior view of male reproductive system.

Epididymis

CHAPTER 8   Pelvis Corpora cavernosa

545

S

Spermatic cord R

L

Testis

I

Corpus spongiosum

Scrotum

Lymph nodes

FIG. 8.89  Coronal, T1-weighted MRI of male pelvis with spermatic cords.

Femoral artery

Rectus Femoral abdominis vein muscle

A

Spermatic cord

Sartorius muscle

Rectus femoris muscle

Tensor fasciae latae muscle

R

L Vastus lateralis muscle

Ischium

Prostate

Rectum

P

Pectineus muscle

Quadratus femoris muscle

FIG. 8.90  Axial, T1-weighted MRI of male pelvis with spermatic cords.

Iliopsoas muscle

CHAPTER 8   Pelvis

546

Femoral Femoral Testicular artery vein artery

Spermatic cords

A

Pectineus muscle

Pubic symphysis

Obturator externus muscle

Superior ramus of pubis

R

L

Femur Ischium

P

Obturator internus muscle

Prostate gland

FIG. 8.91  Axial CT of male pelvis with spermatic cords.

Adductor magnus muscle

Adductor brevis muscle

Adductor longus muscle

A

Penis

Spermatic cords

Rectus femoris muscle

Inguinal lymph node

Vastus lateralis muscle

Sartorius muscle

R

L

Vastus intermedius muscle

Femur

Gluteus maximus muscle Gracilis muscle

Anus

P

Sciatic nerve

FIG. 8.92  Axial, T2-weighted MRI of male pelvis with spermatic cords.

CHAPTER 8   Pelvis

Seminal Vesicles.  The seminal vesicles are paired

accessory glands consisting of coiled tubes that form two pouches, lateral to the vas deferens on the posteroinferior surface of the bladder. They lie superior to the

prostate gland and produce fructose and a coagulating enzyme for the seminal fluid that mixes with sperm prior to ejaculation (Figs. 8.79, 8.80, 8.88, and 8.93–8.96).

A

Seminal vesicles

Bladder

R

L

Rectum

Vas deferens

P

FIG. 8.93  Axial, T2-weighted MRI of seminal vesicles, with endorectal coil.

A

Bladder

Vas deferens Femoral head L

R

Seminal vesicle

Obturator internus muscle

Sacrospinous ligament

Coccyx

P

547

Rectum

FIG. 8.94  Axial, T2-weighted MRI of male pelvis with seminal vesicles.

548

CHAPTER 8   Pelvis

Femoral artery

Femoral vein

Seminal vesicles

A

Spermatic cord

Ureter R

L

Bladder

P

Rectum

FIG. 8.95  Axial CT of male pelvis with seminal vesicles.

Bladder

S

Seminal vesicle

A

P

Retropubic space Pubic symphysis

Corpus cavernosum

Corpus spongiosum

I

Prostate

FIG. 8.96  Sagittal, T2-weighted MRI of prostate gland.

Membranous urethra

CHAPTER 8   Pelvis

Prostate Gland.  The prostate gland is an extraperito-

neal fibromuscular structure and is the largest accessory gland of the male reproductive system. It secretes a thin, slightly alkaline fluid that forms a portion of the seminal fluid. The prostate gland is located inferior to the bladder and surrounds the prosthetic urethra, which courses through the anterior portion of the gland (Figs. 8.79, 8.80, 8.96, and 8.97). The prostate gland has a base adjacent to the neck of the bladder and an apex that is in contact with the perineal membrane. The prostate gland is composed of glandular and fibromuscular tissue and surrounded by a capsule composed of collagen, elastin, and smooth muscle. It can be divided into two lateral lobes, a middle lobe, and an anterior fibromuscular portion. The ejaculatory ducts, which are extensions of the seminal vesicles, descend within the central zone of the gland and open into the prostatic urethra at the verumontanum. The verumontanum is a longitudinal mucosal fold that forms an elliptical segment of the prostatic urethra, marking the point where the ejaculatory ducts enter the urethra (Fig. 8.98). The glandular tissue comprises two-thirds of the prostate’s parenchymal tissue and can be divided into zonal anatomy in sectional imaging. The four main regions are the central, peripheral, transition, and anterior fibromuscular stroma (Figs. 8.98–8.100). The central zone is located at the base of the prostate between the peripheral and transition zones and accounts for approximately 25% of the glandular tissue. It surrounds the ejaculatory ducts and

549

narrows to an apex at the verumontanum. The peripheral zone is the larger of the zones, comprising approximately 70% of the glandular tissue. It extends from the base to the apex along the posterior or rectal surface of the gland and surrounds the distal urethra. The peripheral zone is separated from the central and transition zones by a visible linear boundary referred to as the prostatic pseudocapsule or surgical capsule. The transition zone forms only 5% of the glandular tissue. It consists of two small lobules that are located lateral to the proximal urethra between the verumontanum and the neck of the bladder. This is the portion of the glandular tissue that enlarges due to benign prostatic hypertrophy. The periurethral zone comprises less than 1% of the glandular tissue. It is found embedded along the smooth muscular wall of the urethra. The anterior fibromuscular stroma is devoid of glandular tissue and is composed of fibrous and muscular elements. As it extends laterally and posteriorly, it thins to form the fibrous capsule that surrounds the prostate gland.

Cancer of the prostate gland is the second most common type of cancer in men, occurring with increasing frequency after the age of 55 years with an average age of 65 at time of diagnosis. According to the American Cancer Society, about 1 man in 7 will be diagnosed with prostate cancer during his lifetime.

Suspensory ligament of penis

A

Femoral vein

Femoral artery

Profunda femoris artery

Spermatic cords

R

L

Prostatic urethra

P

Rectum

FIG. 8.97  Axial CT of male pelvis with prostate gland.

Prostate

550

CHAPTER 8   Pelvis S

Transition zone

Central zone

P

Peripheral zone

Anterior fibromuscular stroma

Prostatic urethra

A

Urethra

Seminal vesicle Verumontanum

I

Ejaculatory duct

FIG. 8.98  Zonal anatomy of prostate gland.

CHAPTER 8   Pelvis

Prostatic urethra

Retropubic space

A

Pubic symphysis

Anterior fibromuscular stroma

Central zone

Acetabulum L

R Peripheral zone

Internal obturator muscle Neurovascular bundle

Levator ani muscle

Rectum

P

Rectovesical pouch

FIG. 8.99  Axial, T2-weighted MRI of male pelvis with prostate gland.

Seminal vesicles

S

R

L Ejaculatory duct

Verumontanum Prostatic urethra

Bladder

Peripheral zone

I

Central zone

FIG. 8.100  Coronal, T2-weighted MRI of prostate gland.

551

552

CHAPTER 8   Pelvis

Bulbourethral Glands.  The two small, bulboure-

thral glands (Cowper glands) lie posterolateral to the membranous urethra, embedded in the perineal membrane. These glands secrete an alkaline fluid, which forms a portion of the seminal fluid, into the membranous urethra (Fig. 8.101).

Penis.  The penis, the external reproductive organ, is

attached to the pubic arch via suspensory ligaments. It has two parts: the root, which is attached to the pubic arch, and the body, which remains free. Three cylindrical masses of erectile tissue constitute the root of the penis: two corpora cavernosa and the corpus spongiosum. Each corpus cavernosum consists of a network of

collagen fibers and spaces that become enlarged when filled with blood, contributing to an erection. The corpus spongiosum consists mostly of a dense venous plexus and also contributes to an erection. The two corpora cavernosa form the upper surface, whereas the corpus spongiosum forms the undersurface and contains the greater part of the urethra. At the root of the penis, the corpora cavernosa form the crura, which attach along the ischiopubic ramus. The corpus spongiosum forms the bulb of the penis, which is located between the two crura and is firmly attached to the inferior aspect of the perineal membrane. The distal end of the cylindrical masses forms the glans penis, which surrounds the external urethral meatus (Figs. 8.88 and 8.101–8.105).

Verumontanum Urinary bladder Prostatic urethra

Prostate gland Perineal membrane

Bulbourethral gland Membranous urethra

Root

Penile urethra

Corpora cavernosa

Body

Corpus spongiosum

Prepuce

Glans penis

External urethral orifice

Corpora cavernosa Corpus spongiosum Penile urethra Skin

FIG. 8.101  Anatomy of penis.

CHAPTER 8   Pelvis Peritoneum

S

Sacrum

Seminal vesicle

Bladder

Rectum A

P Prostate gland

Pubic symphysis

Prostatic urethra Anus Perineal membrane Corpus cavernosum

Corpus spongiosum

I

Retropupic space

Penile urethra

FIG. 8.102  Sagittal, T2-weighted MRI of male pelvis with penis.

S

Bladder

Dorsal artery and vein

Pubic symphysis L

R

Corpora cavernosa

Penile urethra

I

Corpus spongiosum

FIG. 8.103  Coronal, T2-weighted MRI of penis.

553

CHAPTER 8   Pelvis

554

Penile urethra

A

Spermatic cord

Adductor longus muscle Adductor brevis muscle Corpora cavernosa (crura)

Pectineus muscle Adductor magnus muscle R

L Ischiopubic ramus

Corpus spongiosum (bulb of penis)

Ischiocavernous muscle

Perineal body Biceps femoris tendon Semitendinosus tendon

Gluteus maximus muscle Semimembranosus tendon

Rectum

P

FIG. 8.104  Axial, T2-weighted MRI of male pelvis with root of penis.

Sartorius muscle

Adductor magnus muscle

Spermatic cord A

Corpus cavernosum

Adductor brevis muscle

Rectus femoris muscle Adductor longus muscle

Tensor fasciae latae muscle

Femur

Quadratus femoris muscle

Anus

P

FIG. 8.105  Axial CT of male pelvis with root of penis.

Corpus spongiosum

Ischial ramus

CHAPTER 8   Pelvis

VASCULATURE Arteries

555

of the internal iliac artery include the obturator, umbilical, and inferior vesical arteries in males; the uterine and vaginal arteries in females; and the middle rectal, internal pudendal, and inferior gluteal arteries (Fig. 8.107). The posterior trunk of the internal iliac artery supplies blood to the posterior and lateral walls of the pelvis, iliac crest, and gluteal region. Branches of the posterior trunk include the iliolumbar, lateral sacral, and superior gluteal arteries. The large external iliac artery does not enter the true pelvis but extends along the pelvic brim to exit the iliac fossa and course under the inguinal ligament to supply the leg. The external iliac artery becomes the femoral artery at approximately the level of the anterior superior iliac spine. Branches of the external iliac artery include the inferior epigastric artery, which supplies blood to the muscles and skin of the anterior abdominal wall, and the deep circumflex iliac artery, which supplies blood to the lateral abdominal muscles (Figs. 8.110–8.120 and Table 8.2).

The abdominal aorta descends into the pelvis anterior to the lumbar vertebrae, slightly to the left of midline. Extending from the dorsal wall of the aorta, just above the aortic bifurcation at the level of the fourth lumbar vertebra, is the median (middle) sacral artery, which continues caudally in front of the sacrum to the apex of the coccyx. The descending aorta bifurcates into the right and left common iliac arteries (Figs. 8.106–8.108). Each common iliac artery bifurcates at the upper margin of the sacroiliac joint into the internal and external iliac arteries (Fig. 8.109). The smaller internal iliac artery extends posteromedially into the pelvis just medial to the external iliac vein and branches into an anterior trunk and a posterior trunk. The anterior trunk of the internal iliac artery supplies blood to the perineum, gluteal region, and pelvic viscera. Branches of the anterior trunk

Right crus of diaphragm

S

Esophagus

Diaphragm

Left gastric artery

Inferior phrenic artery

Celiac trunk

Common hepatic artery Splenic artery

Right suprarenal artery

Superior mesenteric artery

Right renal artery R Right gonadal artery

Abdominal aorta L

Lumbar arteries

Left gonadal artery

Right common iliac artery Inferior mesenteric artery Right internal iliac artery Right external iliac artery Right inguinal ligament

Left internal iliac artery Inferior gluteal artery Femoral artery

I Umbilical artery

Internal pudendal artery

FIG. 8.106  Anterior view of abdominal aorta and vessels.

CHAPTER 8   Pelvis

556

S

Ovarian (gonadal) artery Lumbar artery Inferior mesenteric artery

Deep circumflex iliac artery

Left colic artery

Iliolumbar artery Superior rectal artery External iliac artery

Right common iliac artery

Obturator artery

Median sacral artery

Inferior epigastric artery

Superior gluteal artery

Pubic branch

Lateral sacral artery

Umbilical artery

Internal iliac artery

Uterine artery

Inferior gluteal artery

Internal pudendal artery

Middle rectal artery

Femoral artery

Vaginal artery

Medial circumflex femoral artery

I

FIG. 8.107  Anterior oblique view of iliac arteries.

Right common iliac artery

A

IMA

Left common iliac artery

Gonadal artery and vein

IVC L

R

Psoas muscle

P

Median sacral artery

FIG. 8.108  Axial CT of pelvis with common iliac vessels.

CHAPTER 8   Pelvis Internal iliac artery

A

External iliac artery

Psoas muscle

Iliacus muscle L

R

Ilium External iliac vein

SI joint

P

Internal iliac vein

Sacrum

FIG. 8.109  Axial CT of pelvis with internal and external iliac vessels.

S

Inferior vena cava

Aorta

Deep circumflex iliac artery

Common iliac artery Common iliac vein

External iliac artery R

L External iliac vein

Internal iliac artery

Inferior epigastric artery Inguinal ligament

Femoral artery Femoral vein I

FIG. 8.110  Anterior view of inferior vena cava and abdominal aorta.

557

CHAPTER 8   Pelvis

558

Femoral artery

Femoral vein

Spermatic cord

Rectus abdominis muscle

A

Obturator artery

L

R

Prostate

P

Coccygeus muscle

Coccyx

Rectum

Inferior gluteal artery and vein

FIG. 8.111  Axial, T1-weighted MRI of pelvis with inferior gluteal vessels.

Internal iliac vein

A

Internal iliac artery

Sacroiliac joint

R

L

Ilium

Sacral ala

P

Erector spinae muscles

FIG. 8.112  Axial, T1-weighted MRI of pelvis with internal iliac vessels.

Gluteus maximus muscle

CHAPTER 8   Pelvis

Pectineus muscle

Pubic ramus

Spermatic cord

Rectus abdominis muscle

Femoral vein

A

Femoral artery

Sartorius muscle

Iliopsoas muscle

L

R

Greater trochanter

Femoral head

Quadratus femoris muscle

Prostate

P

Rectum

Internal obturator muscle

FIG. 8.113  Axial, T1-weighted MRI of pelvis with femoral artery and vein.

Iliopsoas muscle

A

Rectus abdominis muscle

Inferior epigastric artery and vein External iliac artery

External iliac vein

L

R

Anterior trunk of internal iliac artery Posterior trunk of internal iliac artery

P

Internal iliac vein

FIG. 8.114  Axial CT of pelvis with iliac vessels.

559

560

CHAPTER 8   Pelvis Obturator artery

A

Femoral vein

Femoral artery

Ilium

R

L

Gluteus maximus muscle

Internal pudendal artery

Inferior gluteal artery

P

Rectal artery

Sacrum

Rectum

FIG. 8.115  Axial CT of pelvis with internal pudendal artery.

A

Bladder

Femoral head Obturator artery Acetabulum L

R

Obturator internus muscle Inferior gluteal artery Gluteus maximus muscle Coccyx

Rectum

P

FIG. 8.116  Axial CT of pelvis with obturator artery.

CHAPTER 8   Pelvis

561

S Abdominal aorta Right renal artery

Spleen

Left renal artery

R

L

Right common iliac artery

Left common iliac artery Left external iliac artery

Right external iliac artery Right internal iliac artery

Left internal iliac artery

Posterior trunk of right internal iliac artery

FIG. 8.117  MRA of descending aorta and iliac vessels.

Anterior trunk of right internal iliac artery

I Proper Common hepatic hepatic artery artery

S

Gastroduodenal artery

Celiac Splenic trunk artery

Superior mesenteric artery Abdominal aorta Inferior mesenteric artery

Median sacral artery

Left common iliac artery

Anterior trunk of internal iliac artery

Internal iliac artery

R

L External iliac artery

Internal pudendal artery Obturator artery

FIG. 8.118  3D CTA of descending aorta and iliac vessels.

Inferior gluteal artery

I

CHAPTER 8   Pelvis

562

S

Abdominal aorta Lumbar artery Inferior mesenteric artery Iliolumbar artery Left common iliac artery Internal iliac artery Superior gluteal artery External iliac artery Inferior gluteal artery Internal pudendal artery Abdominal aorta

FIG. 8.119  Anterior oblique 3D CTA of descending aorta and iliac vessels.

I

S

Left common iliac artery (cut)

Lumbar artery Right common iliac artery External iliac artery Internal iliac artery A

P

Posterior trunk Anterior trunk

Inferior gluteal artery

Obturator artery

Internal pudendal artery

I

FIG. 8.120  3D CTA of iliac vessels.

CHAPTER 8   Pelvis TABLE 8.2

563

  Branches of the Internal and External Iliac Arteries

Arterial Branch

Structures Supplied

Anterior Branch of Internal Iliac Obturator artery Medial thigh Umbilical artery Superior bladder and vas deferens Uterine artery Uterus, cervix, and vagina Vaginal artery Vagina, posteroinferior bladder, and pelvic part of urethra Inferior vesical artery Prostate gland, seminal vesicles, and posteroinferior part of the bladder Middle rectal artery Distal end of rectum, prostate, and seminal vesicles or vagina Internal pudendal artery Anal canal and perineum Inferior gluteal artery Muscles and skin of the buttock and posterior surface of the thigh Posterior Branch of Internal Iliac Iliolumbar artery Lateral sacral artery Superior gluteal artery Branches of External Iliac Artery Inferior epigastric artery Deep circumflex iliac artery

Psoas, iliacus, quadratus lumborum, gluteal muscles, and cauda equina Spinal meninges, roots of the sacral nerves, and muscles and skin of dorsal sacrum Obturator internus, piriformis, and gluteus muscles Ascends abdomen to anastomose with internal thoracic vessels to supply the anterior abdominal wall Ascends abdomen to anastomose with internal thoracic vessels to supply the lateral aspect of the anterior abdominal wall

veins. The internal iliac vein ascends the pelvis medial to the internal iliac artery as it returns blood from the pelvic viscera. Tributaries of the internal iliac vein are similar to those of the branches of the internal iliac artery but with some differences, such as the iliolumbar vein, which usually drains into the common iliac vein. In addition, venous plexuses are formed by the veins in the

Venous Drainage Venous drainage of the pelvis follows a pattern similar to that of the arterial supply. Mainly, the internal iliac veins and their tributaries drain the pelvis (Figs. 8.121 and 8.122). However, there is some drainage through the superior rectal, median (middle) sacral, and gonadal

Esophagus Left phrenic vein

S Left gastric artery

Hepatic veins

Inferior phrenic artery Suprarenal artery Suprarenal vein

Celiac trunk Splenic artery

Right renal vein

Hepatic artery Inferior vena cava

Abdominal aorta

R

L Left renal artery

Testicular or ovarian veins

Superior mesenteric artery Testicular or ovarian artery

Common iliac vein

Common iliac artery

Median sacral vein

Median sacral artery

Internal iliac vein

External iliac artery

External iliac vein

I

FIG. 8.121  Anterior view of inferior vena cava and tributaries.

CHAPTER 8   Pelvis

564

S Left portal vein Left gastric vein

Right portal vein Portal vein

Right gastric vein

Umbilical vein

Splenic vein

Round ligament of liver Renal vein Pancreaticoduodenal vein Inferior vena cava

Superior mesenteric vein

Inferior mesenteric vein

Right renal vein Right common iliac vein

R

Left testicular (ovarian) vein

Iliolumbar veins

Median sacral vein

Right testicular (ovarian) vein Superior rectal vein

Superior gluteal vein

Sigmoid veins

Internal iliac vein

Middle rectal veins

External iliac vein Uterine vein Femoral vein

I

A

S Common iliac vein

Superior gluteal vein Uterine vein

Internal iliac vein

Lateral sacral veins Inferior gluteal vein

External iliac vein

Vesical vein

Deep circumflex iliac vein A

Venous plexus Uterine venous plexus

Inferior epigastric vein

Middle rectal veins Obturator veins

Inferior pudendal vein Rectum

Uterus

Vaginal venous plexus

Bladder

B

Vagina

Vesical venous plexus I

FIG. 8.122  (A) Veins of the pelvis. (B) Female.

P

L

CHAPTER 8   Pelvis

565

S Common iliac vein Internal iliac vein Superior gluteal vein

Deep circumflex iliac vein

Lateral sacral veins

External iliac vein

Inferior vesical/internal pudendal vein

Inferior epigastric vein

Venous plexus

Obturator veins

A

P

Inferior gluteal vein

Vesical veins

Middle rectal veins

Vesical venous plexus

Rectal venous plexus

Deep dorsal vein of penis

Rectum Vesical venous plexus

C

Prostatic venous plexus

Bladder

Prostate I

FIG. 8.122, cont’d  (C) Male.

pelvis and unite to drain mainly into the internal iliac vein (Fig. 8.122). These plexuses include the uterine, vaginal, prostatic, vesical, and rectal. The external iliac veins, extensions of the femoral veins, return blood from the legs. Typically, both external iliac veins course medial to their respective external iliac artery and then change to a posterior position as they ascend to join the common iliac vein at approximately the level of the sacroiliac joint. The common iliac vein arises posterior to the common iliac artery from the junction of the internal and external iliac veins. The inferior vena cava is formed at the level of L5, just a little to the right of the midline, by the union of the common iliac veins. From this level, it continues to ascend the abdomen to the right of the abdominal aorta (Figs. 8.108–8.115 and 8.122).

LYMPH NODES Pelvic lymph nodes include nodal chains or groups that accompany their corresponding vessels. The nodal groups that correspond to pelvic vessels include the common iliac, internal iliac, external iliac, and sacral nodal groups (Fig. 8.123). The common iliac lymph nodes form two groups along the surface of the common iliac artery: a lateral group and a median group. The lateral common iliac group receives lymph from the lower limb and pelvis via the external and internal iliac lymph nodes. The

median common iliac group receives lymph directly from the pelvic viscera and indirectly through the internal iliac and sacral lymph nodes. The obturator nodes, which course along the midportion of the obturator internus muscle, are included in the medial common iliac group. The external iliac lymph nodes lie on the external iliac vessels and drain lymph from the lower limb, abdominal wall, bladder, and prostate in males or uterus and vagina in females. The internal iliac lymph nodes surround the internal iliac vessels and their branches. They receive lymph from all the pelvic viscera, deep parts of the perineum, and gluteal and thigh regions. Sacral lymph nodes lie along the median and lateral sacral arteries. They receive lymph from the posterior pelvic wall, rectum, neck of the bladder, and prostate or cervix. The inguinal lymph nodes drain lymph from the lower limb, perineum, and anterior abdominal wall as far superiorly as the umbilicus, gluteal region, and parts of the anal canal. They can be divided into the superficial inguinal lymph nodes, which are situated distal to the inguinal ligament in the subcutaneous tissue anterior and medial to common femoral vessels, and the deep inguinal lymph nodes, which are fewer in number and are situated medial to the femoral vessels at the approximate level of the ischial tuberosity. Pelvic lymph nodes are considered pathologically enlarged when they exceed 10 mm in the short axis (Figs. 8.124–8.126).

566

CHAPTER 8   Pelvis S Aorta Preaortic nodes

Right common iliac artery Common iliac nodes

Common iliac artery

Sacral nodes R

Internal iliac artery

External iliac nodes External iliac artery

Internal iliac nodes

Right ovary

Uterus

Cervix

Obturator nodes

Vagina Deep inguinal nodes

Superficial inguinal nodes I

FIG. 8.123  Anterior view of pelvic lymph nodes.

S

Ilium

R

L

Inguinal lymph nodes

Sartorius muscle

I

FIG. 8.124  Coronal, T1-weighted MRI of pelvis with lymph nodes.

L

CHAPTER 8   Pelvis Rectus femoris muscle

Sartorius muscle

Femoral nerve

A

567

Inguinal lymph nodes

Femoral artery

Tensor fasciae latae muscle

Femoral vein

Iliopsoas muscle Acetabulum L

R Greater trochanter of femur

Obturator internus muscle

Femoral head Sciatic nerve

P

FIG. 8.125  Axial, T1-weighted MRI of right hip with femoral vessels and inguinal lymph nodes. Hypogastric lymph node metastases

A

Bladder

External iliac artery

R

L External iliac vein

Internal iliac vessels

P

FIG. 8.126  Axial CT of pelvis with enlarged lymph nodes.

REFERENCES Anderson, M. W., & Fox, M. G. (2017). Sectional anatomy by MRI and CT (4th ed.). Philadelphia: Elsevier. Federle, M. P., & Raman, S. P. (2015). Diagnostic imaging: Gastrointestinal (3rd ed.). Philadelphia: Elsevier. Frank, G. (2012). Merrill’s atlas of radiographic positions and radiologic procedures (12th ed.). St. Louis: Mosby. Haaga, J. R., & Boll, D. T. (2017). CT and MRI of the whole body (6th ed.). Philadelphia: Elsevier. Hagen-Ansert, S. L. (2012). Textbook of diagnostic sonography (7th ed.). St. Louis: Elsevier.

Sahani, D. V., & Samir, A. E. (2017). Abdominal imaging (2nd ed.). Philadelphpia: Elsevier. Seidel, H. M., Ball, J. W., & Dains, J. E., et al. (2010). Mosby’s guide to physical examination (7th ed.). St. Louis: Mosby. Standring, S. (2012). Gray’s anatomy, the anatomical basis of clinical practice (41st ed.). New York: Elsevier. Torigian, D. A., & Kitazono, M. T. (2013). Netter’s correlative imaging: Abdominal and pelvic anatomy (1st ed.). Philadelphia: Elsevier. Weir, J., & Abrahams, P. H. (2011). Imaging atlas of human anatomy (4th ed.). London: Elsevier.

CHAPTER

9

Upper Extremity It is sometimes on one’s weakest limbs that one must lean in order to keep going. Jean Rostand, Substance of Man

The intricate anatomy of the musculoskeletal system can make identification of the upper extremity anatomy challenging (Fig. 9.1). A basic knowledge of the anatomy and kinesiology of these areas increases the ability to identify pathology or injury that may occur.

FIG. 9.1  3D CT—healing fracture of the clavicle.

OBJECTIVES • Identify the bony anatomy of the upper extremity. • Identify the components that contribute to the glenoid labrum. • Describe the joint capsules of the shoulder, elbow, and wrist. • List and describe the ligaments and tendons of each upper extremity joint.

• Identify and state the actions of the muscles, as well as their origin and insertion sites. • Identify the major arteries and veins of the upper extremity. • List and identify the nerves that innervate the upper extremity.

OUTLINE SHOULDER, 569 Bony Anatomy, 569 Labrum and Ligaments, 576 Articular Joint Capsule, 585 Bursae, 586 Muscles and Tendons, 587 ELBOW, 606 Bony Anatomy, 608

568

Ligaments, 612 Muscles of the Forearm, 616 WRIST AND HAND, 626 Bony Anatomy, 626 Joints, 633 Ligaments and Fascia, 635 Muscles and Tendons, 644

Copyright © 2019, Elsevier Inc.

NEUROVASCULATURE, 651 Arterial Supply, 651 Venous Drainage, 655 Innervation, 656

CHAPTER 9  Upper Extremity

SHOULDER Bony Anatomy

569

Clavicle.  The clavicle connects the upper limb to the

trunk of the body and provides attachments for several muscles and ligaments. It is a long, slender bone located anteriorly that extends transversely from the sternum to the acromion process of the scapula. The widened ster­ nal end of the clavicle articulates with the manubrium

The bony anatomy that comprises the shoulder girdle includes the clavicle, scapula, and humerus (Figs. 9.2 and 9.3). Acromial end of clavicle Acromioclavicular joint Acromion process

Scapular notch S

Body of clavicle Superior margin Superior angle

Coracoid process

Sternal end of clavicle Sternoclavicular joint

Intertubercular (bicipital) groove

Clavicular notch

Greater tubercle

Manubrium Lateral angle

Lesser tubercle R

L

Glenohumeral joint

Medial margin

Humerus

Lateral margin

Scapula I

Inferior angle

FIG. 9.2  Anterior view of shoulder girdle. Acromial end of Coracoid Right Scapular Scapular clavicle process clavicle notch spine S

Sternal Superior end of Sternoclavicular angle clavicle joint

Acromioclavicular joint Acromion process

Left clavicle

Lateral angle Glenohumeral joint Glenoid fossa Glenoid process Humerus

L R Manubrium of sternum

Lateral margin

I

Scapula

Inferior angle

FIG. 9.3  3D CT of shoulder girdle.

Medial margin

570

CHAPTER 9  Upper Extremity Acromion process

A

Acromioclavicular joint (AC joint)

Clavicle

R

L

P

FIG. 9.4  Axial CT of right shoulder with acromioclavicular joint. Manubrium of sternum

Sternoclavicular joint

A

Sternal end of clavicle

Rib

Rib

Humeral head R

L

Costovertebral joint Thoracic vertebra

P

Scapula

FIG. 9.5  Axial CT of left shoulder with sternoclavicular joint. of the sternum to form the sternoclavicular (SC) joint, and its flattened acromial end articulates with the acromion process of the scapula to form the acromioclavicu­ lar (AC) joint. The medial two-thirds of the body of the clavicle is anteriorly convex, whereas the lateral onethird is flattened and anteriorly concave (Figs. 9.2–9.6).

Scapula.  The scapula is a triangular-shaped flat bone

that forms the posterior portion of the shoulder girdle. It has a medial margin (vertebral border), a lateral margin (axillary border), and a superior margin. The margins are separated by the superior, inferior, and lateral angles

(Figs. 9.2 and 9.3). The anterior surface of the scapula, the subscapular fossa, is flat and slightly concave. The posterior surface of the scapula is divided by the scapular spine into a smaller supraspinous fossa and a larger infra­ spinous fossa (Fig. 9.7). Four projections of the scapula provide attachment sites for the muscles and ligaments contributing to the shoulder girdle. These include the scapular spine, acromion process, coracoid process, and glenoid process (Figs. 9.7–9.10). The scapular spine arises from the upper third of the posterior surface of the scapula and extends obliquely and laterally to give rise to the acromion process. A communication between the

CHAPTER 9  Upper Extremity

S

571

Acromioclavicular joint Clavicle Trapezius muscle

Acromion process

Supraspinatus muscle Supraglenoid tubercle

Deltoid muscle

Glenoid fossa

Head of humerus

Glenohumeral joint L

R

Infraglenoid tubercle

I

FIG. 9.6  Coronal oblique, T1-weighted MRI of right shoulder with acromioclavicular joint. Supraspinous fossa

Scapular notch Coracoid process

Scapular spine

Acromion process

S

Acromion process

Coracoid process Glenoid fossa

Supraglenoid tubercle

Supraspinous fossa Glenoid process

Infraspinous fossa

Infraspinous fossa

Infraglenoid tubercle

Glenoid fossa Infraglenoid tubercle

A

P

I

FIG. 9.7  Posterior view of scapula.

FIG. 9.8  Lateral view of scapula.

supraspinous and infraspinous fossae exists at the spi­ noglenoid notch, which is created where the acromion process and scapular spine converge on the posterior aspect of the scapula. Located on the anterolateral surface of the scapula is a beaklike process termed the coracoid

process, which arises just medial to the glenoid process and functions to protect the shoulder joint, which lies beneath it. The coracoid process is an attachment site for the pectoralis minor, the short head of the biceps brachii, and the coracobrachialis muscles. The scapular notch is

CHAPTER 9  Upper Extremity

572

Intertubercular (bicipital) groove

Lesser tubercle of humerus

Coracoid process

Scapular notch

A

Greater tubercle of humerus

Supraspinous fossa

Humeral head

Scapular spine

Acromion process Glenohumeral joint

Glenoid fossa

P

Glenoid process

FIG. 9.9  3D CT of superior aspect of scapula.

Coracoclavicular ligament

Clavicle

S

Supraspinatus muscle

Acromion process

Infraspinatus muscle

Deltoid muscle

Glenoid fossa of scapula

Coracoid process A

P

Subscapularis muscle

Teres minor muscle Infraglenoid tubercle Triceps brachii tendon (long head) I

FIG. 9.10  Sagittal oblique, T1-weighted MRI of shoulder.

located just medial to the coracoid process on the superior margin of the scapula and allows for the passage of the suprascapular nerve (Figs. 9.2, 9.3, and 9.9). The glenoid process, the largest of the projections, forms the lateral angle of the scapula and ends in a depression called the glenoid fossa (glenoid cavity) (Figs. 9.3 and 9.6–9.11). There are two tubercles associated with the glenoid fossa, an upper supraglenoid tubercle and a

lower infraglenoid tubercle, which serve as attachment sites for the long heads of the biceps brachii and triceps brachii muscles, respectively (Figs. 9.6–9.8, 9.10, and 9.12). The shallow articular surface of the glenoid fossa joins with the relatively large articular surface of the humeral head to create the freely moving glenohumeral joint (Figs. 9.2, 9.3, 9.6, 9.9, 9.11, and 9.12).

CHAPTER 9  Upper Extremity

Subscapularis tendon

Humerus

A

573

Middle Coracoid glenohumeral process ligament Clavicle

Greater tubercle Glenohumeral joint R

L

P

Glenoid fossa

Scapular spine

Scapula

FIG. 9.11  Axial CT of right shoulder, post-arthrogram. Supraglenoid tubercle

Glenohumeral joint S

Acromion process

Humeral head

Greater tubercle R

L

Glenoid fossa

Infraglenoid tubercle

I

FIG. 9.12  Coronal oblique, T1-weighted MRI of left shoulder.

Proximal Humerus.  The humerus is a long bone that

articulates with the scapula superiorly and the radius and ulna inferiorly. It consists of a proximal end, a body (shaft), and a distal end (Fig. 9.13). The proximal end is formed by the head of the humerus. Two tubercles pro­ ject from the humeral head to provide attachment sites for tendons and ligaments. The lesser tubercle is located on the anterior surface of the humeral head, whereas the greater tubercle is located on the lateral surface of the

humeral head (Figs. 9.12–9.15). The tubercles are separated by the intertubercular (bicipital) groove (Figs. 9.9 and 9.13–9.15). The humerus has two necks, the more proximal anatomic neck and the surgical neck, located inferior to the tubercles just distal to the humeral head (Figs. 9.13 and 9.16). In the middle of the body or shaft of the humerus, on the anterior surface, is the roughened area of the deltoid tuberosity, which provides attachment for the deltoid muscle (Fig. 9.13).

574

CHAPTER 9  Upper Extremity

Greater tubercle

Head of humerus

Lesser tubercle

Proximal end

Anatomic neck Surgical neck

Intertubercular groove

Radial groove Deltoid tuberosity

Body (shaft)

Medial supracondylar ridge Lateral supracondylar ridge

Lateral epicondyle

Coronoid fossa Olecranon fossa

Radial fossa

Medial epicondyle

Capitulum

Distal end

Trochlea Anterior

Posterior

FIG. 9.13  Humerus. Left, Anterior view. Right, Posterior view.

Biceps brachii tendon (long head)

Lesser tubercle

A

Glenohumeral Coracohumeral ligament ligament

Greater tubercle Coracoid process Subscapularis tendon Glenoid labrum R

L

Intertubercular groove

Deltoid muscle

P

Infraspinatus muscle

FIG. 9.14  Axial, T1-weighted MRI of right shoulder.

Scapular spine

CHAPTER 9  Upper Extremity Biceps brachii tendon Lesser Subscapularis (long head) tubercle tendon A

Greater tubercle

575

Coracoid process

Deltoid muscle Subscapularis tendon R

L

Intertubercular groove

Glenoid fossa

Infraspinatus muscle

P

Middle glenohumeral ligament

Supraspinatus muscle

FIG. 9.15  Axial CT of right shoulder, post-arthrogram.

Acromion process

S

Subacromialsubdeltoid bursa

Supraspinatus tendon

Deltoid muscle

Biceps brachii tendon (long head) Superior glenoid labrum

R

L

Glenoid process

Inferior glenoid labrum

Anatomic neck

I

Surgical neck

FIG. 9.16  Coronal oblique, T2-weighted MRI of left shoulder with subacromial-subdeltoid bursa.

576

CHAPTER 9  Upper Extremity

Labrum and Ligaments The outer rim of the glenoid fossa is surrounded by a fibrocartilaginous ring termed the glenoid labrum, which functions to deepen the articular surface of the glenoid fossa (Fig. 9.17). Superiorly, the glenoid labrum blends with the tendon of the long head of the biceps brachii

muscle (Fig. 9.16). In cross-section, it appears triangular (Figs. 9.14 and 9.18). The three glenohumeral ligaments (superior, middle, and inferior) thicken the fibrous capsule that surrounds the shoulder joint and contribute to the formation of the glenoid labrum (Figs. 9.14, 9.17, and 9.19). They extend from the supraglenoid tubercle of the scapula to the lesser tubercle of the humerus. The Coracoacromial arch S

Acromioclavicular ligament

Clavicle Supraspinatus tendon Coracoacromial ligament Coracoid process

Biceps brachii tendon (long head)

Superior glenohumeral ligament

Acromion process Glenoid fossa

Subscapularis tendon A

P

Edge of opening into subscapularis bursa

Glenoid labrum

Joint capsule

Joint capsule

Middle glenohumeral ligament Inferior glenohumeral ligament

I

FIG. 9.17  Lateral view of glenohumeral ligaments and glenoid labrum. Superior glenoid labrum

S

Acromion process

Trapezius muscle Deltoid muscle Supraspinatus muscle

R

L

Subscapularis muscle

Glenoid fossa

I

FIG. 9.18  Coronal oblique, T1-weighted MRI of left shoulder with glenoid labrum.

CHAPTER 9  Upper Extremity Acromioclavicular ligaments Acromion process

S

Coracoacromial ligament Clavicle

Coracoclavicular ligaments Coracoid process Superior Middle Inferior

I

Transverse humeral ligament

Glenohumeral ligaments

Coracohumeral ligament

FIG. 9.19  Anterior view of shoulder ligaments.

Coracoacromial ligament

577

coracohumeral ligament passes from the lateral side of the coracoid process of the scapula to the greater tubercle of the humerus (Figs. 9.14 and 9.19). The coraco­ acromial ligament is another important ligament located on the anterior portion of the shoulder. As this ligament joins the coracoid process and acromion, it forms a strong bridge, termed the coracoacromial arch, which protects the humeral head and rotator cuff tendons from direct trauma and prevents displacement of the humeral head superiorly (Figs. 9.17, 9.19, and 9.20). The coracoclavicular ligaments help to maintain the position of the clavicle, in relation to the acromion, by spanning the distance between the clavicle and coracoid process of the scapula (Figs. 9.19 and 9.21–9.23). The acromioclavicular ligament, at the acromioclavicular joint, provides support for the superior surface of the shoulder (Figs. 9.17, 9.19, 9.22, and 9.24). The trans­ verse humeral ligament is a broad band of connective tissue passing from the greater tubercle to the lesser tubercle of the humerus, forming a bridge over the intertubercular groove for protection of the long head of the biceps tendon (Figs. 9.19 and 9.27). The ligaments of the shoulder are shown in Figs. 9.20–9.35.

Supraspinatus tendon

S

Acromion process

Infraspinatus tendon

Humeral head

A

P

Deltoid muscle

Biceps brachii tendon (long head)

I

Coracobrachialis muscle

FIG. 9.20  Sagittal oblique, T1-weighted MRI of shoulder.

Teres minor muscle

578

CHAPTER 9  Upper Extremity Coracohumeral Coracoclavicular ligament ligament

Supraspinatus muscle

S

Acromion process

A

P Infraspinatus muscle

Coracoid process

Subscapularis muscle

Coracobrachialis muscle

I

Teres major Teres minor Deltoid muscle muscle muscle

FIG. 9.21  Sagittal oblique, T1-weighted MRI of shoulder with coracohumeral ligament.

Coracoclavicular ligament

Clavicle

Acromioclavicular ligament S

Superior glenoid labrum

Acromion process Infraspinatus muscle Teres minor muscle

Supraspinatus muscle

Deltoid muscle

Coracohumeral ligament A

P

Coracoid process

Teres major muscle

Brachial plexus

Triceps muscle

Subscapularis tendon Anterior capsule of shoulder joint Coracobrachialis muscle

Subscapularis muscle

I

Glenohumeral joint

FIG. 9.22  Sagittal oblique, T1-weighted MRI of shoulder with acromioclavicular ligament.

CHAPTER 9  Upper Extremity Coracoacromial ligament

S

Coracoclavicular ligament Clavicle

Trapezius muscle

Coracohumeral ligament

Coracoid process

Head of humerus

Subscapularis muscle

R

L

Deltoid muscle Brachial plexus

I

FIG. 9.23  Coronal oblique, T1-weighted MRI of right shoulder with coracoacromial ligament.

Acromion process

Acromioclavicular ligament

AC joint

S

Biceps brachii tendon (long head)

Clavicle

Superior glenoid labrum

Trapezius muscle

Supraspinatus tendon

Supraspinatus muscle

Deltoid muscle

Glenoid process

Greater tubercle of humerus

Inferior glenoid labrum

R

L

Glenohumeral joint Subscapularis muscle Axillary recess Teres major muscle

I

FIG. 9.24  Coronal oblique, T1-weighted MRI of right shoulder with glenoid labrum.

579

CHAPTER 9  Upper Extremity

580

Coracoacromial ligament

Coracoid process

A

Head of humerus Supraspinatus muscle R

L

Deltoid muscle Acromion process Scapular spine

P

FIG. 9.25  Axial, T1-weighted MRI of right shoulder with coracoacromial ligament.

Middle glenohumeral ligament

Coracohumeral ligament

A

Biceps brachii tendon Coracoid (short head) process

Anterior glenoid labrum Subscapularis tendon

Greater tubercle

Subscapularis muscle Glenoid process

Deltoid muscle R

L

Infraspinatus tendon Infraspinatus muscle

P

FIG. 9.26  Axial, T1-weighted MRI of right shoulder with coracohumeral ligament.

CHAPTER 9  Upper Extremity Biceps brachii tendon (long head)

Lesser tubercle

Subscapularis Coracobrachialis tendon muscle

A

Transverse humeral ligament

Middle glenohumeral ligament

Greater tubercle

Anterior glenoid labrum

Deltoid muscle

Subscapularis muscle Body of scapula

R

L Spinoglenoid notch

Teres minor tendon

Suprascapular artery and nerve Infraspinatus muscle

Posterior joint capsule

Posterior glenoid labrum

P

Teres minor muscle

FIG. 9.27  Axial, T1-weighted MRI of right shoulder with glenoid labrum.

S Clavicle Coracohumeral ligament and joint capsule Superior glenoid labrum Coracoid process R

L Superior glenohumeral ligament

Biceps brachii tendon (long head)

Inferior glenoid labrum

Inferior glenohumeral ligament

I

FIG. 9.28  Coronal oblique, T2-weighted MRI of right shoulder, post-arthrogram.

581

CHAPTER 9  Upper Extremity

582

Supraspinatus tendon

S

Trapezius muscle

Superior labrum Deltoid muscle

Glenoid process

Greater tubercle R

L

Head of humerus

Inferior labrum Axillary recess

Inferior glenohumeral ligament

Joint capsule

I

FIG. 9. 29  Coronal oblique, T2-weighted MRI of right shoulder, post-arthrogram with axillary recess.

Biceps brachii tendon (long head)

A

Biceps brachii tendon (short head)

Coracoid process

Superior glenohumeral ligament Deltoid muscle

Superior glenoid labrum

Infraspinatus tendon R

L

Head of humerus

Supraspinatus muscle Scapular spine Infraspinatus muscle P

FIG. 9.30  Axial, T2-weighted MRI of right shoulder, post-arthrogram.

CHAPTER 9  Upper Extremity Transverse humeral ligament

Biceps brachii tendon (long head)

A

Subscapularis tendon

Coracobrachialis muscle

Intertubercular groove

Anterior glenoid labrum

Greater tubercle

Middle glenohumeral ligament

Deltoid muscle R

L Glenoid process

Teres minor tendon

Scapula

Subscapularis muscle

Posterior glenoid labrum

P

Infraspinatus muscle

FIG. 9.31  Axial, T2-weighted MRI of right shoulder, post-arthrogram with glenoid labrum. Transverse humeral ligament

A

Synovial sheath

Biceps brachii tendon (long head) Greater tubercle

Inferior glenohumeral ligament

Deltoid muscle

Anterior glenoid labrum R

L Glenoid process

Teres minor tendon

Subscapularis muscle

Teres minor muscle

Posterior glenoid joint capsule

Posterior glenoid labrum

P

Infraspinatus muscle

FIG. 9.32  Axial, T2-weighted MRI of right shoulder, post-arthrogram with joint capsule.

583

CHAPTER 9  Upper Extremity

584

Clavicle

AC joint

Acromion process

S

Deltoid muscle Supraspinatus muscle Coracoacromial ligament Infraspinatus tendon

Coracohumeral ligament A

P

Subscapularis tendon

Teres minor tendon

Biceps brachii tendon (short head)

I

Biceps brachii tendon (long head)

FIG. 9.33  Sagittal oblique, T1-weighted MRI of shoulder, post-arthrogram.

Coracohumeral ligament

Superior glenoid Clavicle labrum

S

Supraspinatus muscle

Acromion process Infraspinatus tendon

Superior glenohumeral ligament

Glenoid fossa

Coracoclavicular ligament

Joint capsule Teres minor tendon

Coracoid process A

P

Subscapularis tendon Inferior glenoid labrum

Middle glenohumeral ligament Inferior glenohumeral ligament Coracobrachialis muscle

I

Axillary recess

FIG. 9.34  Sagittal oblique, T1-weighted MRI of shoulder, post-arthrogram with glenoid labrum.

CHAPTER 9  Upper Extremity

585

P Supraspinatus tendon

Infraspinatus tendon

Posterior glenoid labrum

Head of humerus

Glenoid process

Inferior glenohumeral ligament A

Anterior glenoid labrum

Subscapularis muscle

FIG. 9.35  T2-weighted, MRI of right shoulder, post-arthrogram in abduction external rotation (ABER) position.

Articular Joint Capsule The articular joint capsule completely encloses the shoulder joint and is quite thin and loose to allow for extreme freedom of movement. When the arm is adducted, the capsule sags to form a pouchlike area termed the axillary recess (Figs. 9.29, 9.34, and 9.36). The capsule is attached medially to the glenoid fossa of the scapula and

Subacromial bursa

laterally to the anatomic neck of the humerus. It is strengthened by several muscles and ligaments, including the rotator cuff muscles and the long head of the biceps brachii muscle, as well as the glenohumeral and coracohumeral ligaments. There are two openings of the joint capsule. The first is to allow for the passage of the long head of the biceps brachii, and the second establishes a

Acromioclavicular joint S

Clavicle

Supraspinatus muscle

Greater tubercle of humerus Articular joint capsule Biceps brachii tendon (long head) Subdeltoid bursa

Glenoid fossa

Synovial sheath

Scapula Inferior glenoid labrum

Deltoid muscle

Axillary recess Humerus

Biceps brachii muscle I

FIG. 9.36  Anterior cross-section of shoulder joint.

586

CHAPTER 9  Upper Extremity

communication between the joint and the subscapularis bursa. A synovial membrane lines the fibrous capsule and extends to the glenoid labrum and neck of the humerus. The synovial membrane provides a sheath for the tendon of the long head of the biceps brachii muscle, where it passes into the joint cavity through the intertubercular groove, extending as far as the surgical neck of the humerus (Figs. 9.28–9.36).

Bursae The tendons and ligaments of the shoulder joint are cushioned by several fluid-filled bursae. Bursae, within the shoulder, reduce friction where large muscles and tendons pass across the joint capsule. Two prominent shoulder

Acromion process

bursae include the subacromial-subdeltoid and subscapular bursae (Figs. 9.36 and 9.37). The subacromialsubdeltoid bursa is the main bursa of the shoulder and the largest bursa within the body. Beginning at the coracoid process, the bursa extends laterally over the superior surface of the supraspinatus and infraspinatus tendons, extends beyond the acromion, and continues beneath the deltoid muscle to the greater tubercle of the humerus. This bursa cushions the rotator cuff muscles and coracoacromial arch (Fig. 9.16). The subscapular bursa is located between the subscapularis tendon and the scapula and communicates with the synovial cavity through an opening in the joint capsule. This bursa protects the subscapularis tendon, where it passes inferior to the coracoid process and over the neck of the scapula (Fig. 9.37).

Subacromial bursa Coracoacromial ligament

Subdeltoid bursa

Coracohumeral ligament

S Supraspinatus muscle Deltoid muscle (reflected

Coracoid process R

L

Synovial sheath

Subscapularis muscle

Biceps brachii tendon (long head)

Humerus

I

Inferior glenohumeral ligament

FIG. 9.37  Anterior view of shoulder with subacromial-subdeltoid bursa.

CHAPTER 9  Upper Extremity

the external occipital protuberance and to the vertebral column via the ligamentum nuchae and spinous processes of C7–T12. It inserts on the clavicle, acromion process, and scapular spine. The trapezius muscle functions to stabilize the scapula, as well as to elevate, retract, and depress the scapula. The levator scapulae muscle lies deep in the neck and functions to elevate and rotate the scapula. It extends from the transverse processes of C1–C4 to the superior angle and medial border of the scapula above its spine (Fig. 9.38). The latissimus dorsi muscle covers the inferior portion of the back as it extends from the spinous processes of the inferior six thoracic vertebrae, iliac crest, and inferior three or four ribs to the distal end of the intertubercular groove of the humerus. The latissimus dorsi medially rotates, extends, and adducts the humerus (Fig. 9.38). The rhomboid muscles, major and minor, lie deep to the trapezius muscle. The rhomboid major is wider than the rhomboid minor. They parallel each other as they span from the ligamentum nuchae and spinous processes of C7–T5 to the medial border of the scapula. They function to retract the scapula and fix the scapula to the thoracic wall (Figs. 9.38–9.42).

Muscles and Tendons Numerous muscles and their tendons provide stability for the shoulder joint and movement of the upper arm. These can be separated into four muscle groups: (1) muscles that connect the upper extremity to the vertebral column, (2) muscles of the scapula, (3) muscles that connect the upper extremity to the anterior thoracic wall, and (4) muscles of the upper arm.

Muscles Connecting the Upper Extremity to the Vertebral Column  Trapezius Levator scapulae Latissimus dorsi Rhomboid major Rhomboid minor

Muscles connecting the upper extremity to the vertebral column are shown in Figs. 9.38–9.42 and are described in Table 9.1. The large triangular trapezius muscle covers the posterior aspect of the neck and superior half of the back (Fig. 9.38). It connects the upper limb to the cranium via S

Rhomboid minor Levator scapulae

Rhomboid major

Clavicle

Trapezius

Supraspinatus

Deltoid

Spine of scapula Infraspinatus Teres minor Scapula

587

R

L

Teres major Humerus

Spinous process

Medial border of scapula

Latissimus dorsi

I

FIG. 9.38  Posterior view of trapezius, rhomboid, levator scapulae, and latissimus dorsi muscles.

CHAPTER 9  Upper Extremity

588

Clavicle

A Deltoid muscle

Supraspinatus muscle

R

L

Erector spinae muscles

Splenius capitis muscle

Acromion process

Levator scapulae muscle

Scapula

P

Trapezius muscle

FIG. 9.39  Axial CT of left shoulder with trapezius muscle.

Subclavian vein

Clavicle

A

Subclavius muscle

Coracoid process

Deltoid muscle

R

L Humeral head

Supraspinatus muscle

Trapezius muscle

Scapula

P

Axillary vein

Scapular spine

FIG. 9.40  Axial CT of left shoulder with deltoid muscle.

CHAPTER 9  Upper Extremity

Clavicle

Subclavius muscle

Pectoralis major muscle

589

Pectoralis minor muscle

A

Humeral head

R

L Deltoid muscle

Serratus anterior muscle

Supraglenoid notch

Rhomboid major muscle

Infraspinatus muscle Trapezius muscle

P

Subscapularis muscle

Scapula

Suprascapular artery and nerve

FIG. 9.41  Axial CT of left shoulder with subscapularis muscle.

Pectoralis major muscle

Pectoralis minor muscle

Latissimus dorsi muscle

A

Teres major muscle

Deltoid muscle

R

L

Intercostal muscle Rhomboid major muscle Trapezius muscle

Serratus anterior muscle

Subscapularis muscle

P

Infraspinatus muscle

FIG. 9.42  Axial CT of left shoulder with pectoralis muscles.

Scapula

Teres minor muscle

590

CHAPTER 9  Upper Extremity

TABLE 9.1

Muscles Connecting the Upper Extremity to the Vertebral Column

Muscle

Origin

Insertion

Primary Actions

Trapezius

External occipital protuberance, ligamentum nuchae, spinous processes of C7–T12 Transverse processes of C1–C4

Clavicle, acromion process, and spine of scapula Superior angle and medial border of scapula Distal end of intertubercular groove of the humerus Medial border of scapula

Stabilizes, elevates, retracts, and depresses scapula Elevates scapula

Levator scapulae Latissimus dorsi Rhomboid major Rhomboid minor

Spinous process of T6–T12, iliac crest, and inferior three or four ribs Ligamentum nuchae and spinous processes of C7–T1 Spinous processes of T2–T5

Medial border of scapula

Muscles of the Scapula  Deltoid Teres major Teres minor Supraspinatus Infraspinatus Subscapularis

Muscles of the scapula are shown in Figs. 9.20–9.35 and 9.38–9.57 and described in Table 9.2. The large deltoid muscle originates on the clavicle, acromion, and scapular spine to blanket the shoulder joint as it extends to insert on the deltoid tuberosity of the humerus. This powerful muscle forms the rounded contour of the shoulder and functions primarily to abduct the arm (Figs. 9.38 and 9.53). The teres major muscle is a flat rectangular muscle that adducts and medially rotates the arm. It extends from the inferior angle of the scapula to the medial aspect or lip of the intertubercular groove of the humerus (Figs. 9.38 and 9.54A). The four remaining muscles, supraspinatus, infraspi­ natus, teres minor, and subscapularis, closely surround the scapula and constitute the rotator cuff (Figs. 9.38 and 9.54–9.57). The rotator cuff provides dynamic stability to the shoulder joint and allows for adduction, abduction, and rotation of the humerus. The supraspinatus, infraspinatus, and teres minor muscles are located on the posterior aspect of the scapula. The tendons

Extends, medially rotates, and adducts the humerus Retracts scapula and fixes scapula to thoracic wall Retracts scapula and fixes scapula to thoracic wall

of these muscles insert on the greater tubercle of the humerus. The supraspinatus muscle lies in the supraspinous fossa of the scapula and helps abduct the arm. The tendon of the supraspinatus muscle is the most frequently injured tendon of the rotator cuff because of possible impingement as it extends under the acromioclavicular joint and continues over the humeral head (Figs. 9.54B and 9.57). The infraspinatus muscle is a triangular muscle that lies below the scapular spine in the infraspinous fossa. It acts to laterally rotate the arm (Fig. 9.54A). Lying along the inferior border of the infraspinatus muscle is the elongated teres minor muscle, which also acts to laterally rotate the arm (Figs. 9.54B, 9.56, and 9.57). The subscapularis muscle is the only muscle of the rotator cuff located on the anterior surface of the scapula; its tendon inserts on the lesser tubercle of the humerus. The subscapularis muscle acts to medially rotate the humerus (Fig. 9.55).

The majority of rotator cuff lesions are a result of chronic impingement of the supraspinatus tendon against the acromial arch. The most susceptible area is approximately 1 cm from the insertion site of the supraspinatus tendon. This location is commonly referred to as the critical zone.

CHAPTER 9  Upper Extremity A

Supraspinatus muscle Infraspinatus muscle R

L Deltoid muscle

Scapular spine

P

FIG. 9.43  Axial, T1-weighted MRI of right shoulder.

Greater tubercle

Coracohumeral ligament A

Deltoid muscle

Glenoid process

Coracoid process

R

L

Supraglenoid notch

Suprascapular artery and nerve

P

Infraspinatus muscle

FIG. 9.44  Axial, T1-weighted MRI of right shoulder with deltoid muscle.

Scapular spine

591

592

CHAPTER 9  Upper Extremity

Deltoid muscle

Transverse humeral ligament

A

Biceps brachii tendon (long head)

Biceps brachii tendon (short head)

Subscapularis tendon Anterior glenoid labrum

R

L

Glenoid process Suprascapular artery and nerve

Posterior glenoid labrum

P

Infraspinatus muscle

FIG. 9.45  Axial, T1-weighted MRI of right shoulder with long head of biceps tendon.

A

Lesser tubercle

Biceps brachii tendon (long head)

Biceps brachii tendon (short head)

Greater tubercle

Coracobrachialis muscle R

L

Deltoid muscle

Middle glenohumeral ligament

Posterior glenoid labrum

Subscapularis muscle

Teres minor muscle

P

FIG. 9.46  Axial, T1-weighted MRI of right shoulder with subscapularis muscle.

CHAPTER 9  Upper Extremity

593

S Acromion process Infraspinatus muscle

Deltoid tendon Deltoid muscle

Teres minor muscle R

L

Brachial plexus

Axillary artery and vein

I

FIG. 9.47  Coronal oblique, T1-weighted MRI of right shoulder.

S Trapezius muscle

Acromion process Supraspinatus tendon

Supraspinatus muscle

Deltoid muscle

Superior glenoid labrum

Humerus Glenoid process R

L

Subscapularis muscle

Axillary nerve

Posterior humeral circumflex artery

Coracobrachialis muscle

I

FIG. 9.48  Coronal oblique, T1-weighted MRI of right shoulder with supraspinatus tendon.

594

CHAPTER 9  Upper Extremity

Clavicle

Suprascapular artery and nerve

Supraspinatus muscle

S

Trapezius muscle

Coracoid process

Coracohumeral ligament

R

L

Deltoid muscle

Biceps brachii tendon (long head)

Humerus

I

Brachial artery

Subscapularis muscle

FIG. 9.49  Coronal oblique, T1-weighted MRI of right shoulder with long head of biceps tendon.

Coracohumeral ligament

Coracoid process

S

Clavicle

Trapezius muscle

Coracoacromial ligament

R

L

Deltoid muscle

Biceps brachii tendon

Subscapularis tendon

I

Subscapularis muscle

Brachial artery

FIG. 9.50  Coronal oblique, T1-weighted MRI of right shoulder with subscapularis tendon.

CHAPTER 9  Upper Extremity CoracoSupraclavicular spinatus ligament tendon

AcromioSupraclavicular spinatus joint muscle S

595

InfraAcromion spinatus process tendon

Coracohumeral ligament Deltoid muscle Coracoid process A

P

Subscapularis muscle

FIG. 9.51  Sagittal oblique, T1-weighted MRI of shoulder.

Coracohumeral ligament

Coracobrachialis muscle

Subscapularis tendon

Superior glenoid labrum

I

Humerus

S

Teres minor muscle

Infraspinatus muscle

Acromio- SupraInfraAcromion clavicular spinatus spinatus process ligament muscle muscle

Coracoid process

Glenoid fossa

A

FIG. 9.52  Sagittal oblique, T1-weighted MRI of shoulder teres minor muscle.

TABLE 9.2

P

Deltoid muscle

Coracobrachialis muscle

Brachial plexus

I

Teres minor muscle

Triceps muscle

Teres Deltoid major muscle muscle

Muscles of the Scapula

Muscle

Proximal/Medial Attachment

Distal/Lateral Attachment

Primary Action

Deltoid

Deltoid tuberosity of humerus

Teres major Teres minor

Clavicle, acromion process, and spine of scapula Inferior angle of scapula Axillary border of scapula

Supraspinatus Infraspinatus

Supraspinous fossa of scapula Infraspinous fossa of scapula

Greater tubercle of humerus Greater tubercle of humerus

Subscapularis

Subscapular fossa of scapula

Lesser tubercle of humerus

Flexes and medially rotates abductor, extensor, and lateral rotator of humerus Adducts and medially rotates humerus Laterally rotates humerus and stabilizes glenohumeral joint Abducts humerus and stabilizes glenohumeral joint Laterally rotates humerus and stabilizes glenohumeral joint Medially rotates humerus and stabilizes glenohumeral joint

Intertubercular groove of humerus Greater tubercle of humerus

CHAPTER 9  Upper Extremity

596

S Acromion process Clavicle Spine of scapula

Deltoid muscle

A P

Deltoid tuberosity of humerus

I

FIG. 9.53  Lateral view of deltoid muscle.

Supraspinous fossa

Supraspinatus muscle

Clavicle S

Spine of scapula S

Acromion process Greater tubercle

Acromion process Greater tubercle

R L

L

Humerus

R

Teres minor muscle Teres major muscle Infraspinatus muscle

A

I Infraspinous fossa

B

I

Lateral border of scapula

FIG. 9.54  (A) Posterior view of teres major and infraspinatus muscles. (B) Posterior view of supraspinatus and teres minor muscles. Coracoid process Acromion process

S

Clavicle

Greater tubercle Lesser tubercle L

R

Subscapularis muscle

I

FIG. 9.55  Anterior view of subscapularis muscle.

CHAPTER 9  Upper Extremity Pectoralis major muscle

Pectoralis Coracobrachialis bursa minor muscle Cephalic vein A Coracobrachialis muscle

First rib

Middle glenohumeral ligament Biceps brachii tendon (long head)

Axillary vein

Greater tubercle

Axillary artery Serratus anterior muscle

Subdeltoid (subacromial) bursa

Cords of brachial plexus

Head of humerus S

Subscapularis bursa Glenoid labrum

Glenoid fossa Deltoid muscle Infraspinatus branches of suprascapular vessels and nerves

R

Infraspinatus bursa Infraspinatus muscle Trapezius muscle P Subscapularis muscle

Scapula

FIG. 9.56  Axial view of shoulder muscles.

Coracoclavicular ligament

S Acromioclavicular joint

Clavicle

Coracoacromial ligament Acromion process

Coracoid process Superior glenohumeral ligament

Biceps brachii tendon (long head)

Opening into subscapularis bursa

Glenoid fossa

Middle glenohumeral ligament

Glenoid labrum

P

Joint capsule

A

Coracoclavicular ligament Clavicle

Acromioclavicular joint Coracoacromial ligament

Coracoid process

Supraspinatus muscle

Biceps brachii tendon (long head)

Acromion

Superior glenohumeral ligament

Infraspinatus muscle Glenoid fossa

Opening into subscapular bursa

Glenoid labrum Teres minor muscle

Middle glenohumeral ligament

Triceps brachii tendon (long head)

Subscapularis muscle Joint capsule

I

FIG. 9.57  Lateral view of rotator cuff muscles.

597

598

CHAPTER 9  Upper Extremity

Muscles Connecting the Upper Extremity to the Anterior and Lateral Thoracic Walls  Pectoralis major Pectoralis minor Serratus anterior Subclavius

Muscles connecting the upper extremity to the anterior and lateral thoracic walls are shown in Figs. 9.39–9.42, 9.56, 9.58, 9.59, and 9.68 and described in Table 9.3. The pectoralis muscles (major and minor), located on the anterior surface of the chest, primarily aid in the movement of the upper limb (Fig. 9.58). The large fan-shaped pectoralis major muscle, which has two heads, covers the Coracoid process Clavicle

superior part of the thorax. It spans from the sternum (sternal head), clavicle (clavicular head), cartilaginous attachments of the upper six ribs, and the aponeurosis of the external oblique muscle to the lateral aspect or lip of the intertubercular groove of the humerus. Its primary functions are to adduct, medially rotate, flex, and extend the humerus and to assist in forced inspiration. The smaller triangular-shaped pectoralis minor muscle lies beneath the pectoralis major muscle and acts to depress the scapula and assist the serratus anterior muscle in pulling the scapula forward. It extends from the coracoid process to the anterior surface of the third to fifth ribs (Fig. 9.58). The serratus (sawlike) anterior muscle is visualized on the lateral border of the thorax. It extends from the first

Subclavius muscle S

Pectoralis major muscle: Clavicular head Sternal head

Lateral lip of intertubercular groove R L Pectoralis minor muscle Fifth rib Sternum

Costal cartilage

I

FIG. 9.58  Anterior view of pectoralis and subclavius muscles. Glenoid fossa

Clavicle

S

Sternum Serratus anterior muscle

Scapula

R

L

Ninth rib

I

FIG. 9.59  Anterior view of serratus anterior muscle.

CHAPTER 9  Upper Extremity TABLE 9.3

599

Muscles Connecting the Upper Extremity to the Anterior and Lateral Thoracic Wall

Muscle

Proximal/Medial Attachment

Distal/Lateral Attachment

Primary Action

Pectoralis major

Lateral lip intertubercular groove of humerus

Adducts, medially rotates, and flexes humerus

Pectoralis minor

Medial half of clavicle (clavicular head), manubrium and body of sternum (sternal head), aponeurosis of external oblique muscle and six upper costal cartilages Anterior surface of third to fifth ribs

Coracoid process of scapula

Serratus anterior Subclavius

Angles of first to eighth or ninth ribs First rib and cartilage

Medial border of scapula Inferior surface of clavicle

Depresses and downwardly rotates scapula; assists in scapular protraction and stabilizes scapula Rotates, stabilizes, and protracts scapula Stabilizes the clavicle and depresses the shoulder

through eighth or ninth ribs to the medial border of the scapula. The primary action of the serratus anterior muscle is to protract and stabilize the scapula (Fig. 9.59). The subclavius, a small triangular-shaped muscle that spans between the first rib and clavicle, acts to stabilize the clavicle and depress the shoulder (Fig. 9.58).

Muscles of the Upper Arm.  The muscles of the up-

per arm can be divided into ventral and dorsal groups according to their position. The ventral group contains the biceps brachii muscle, brachialis muscle, and coracobrachialis muscle, and the dorsal group consists of the triceps brachii muscle and anconeus muscle. These muscles are shown in Figs. 9.20–9.34, 9.43–9.52, 9.56, and 9.60–9.84 and described in Table 9.4.

Acromion process

S

Ventral Group  Biceps brachii Brachialis Coracobrachialis

The muscles of the ventral group are shown in Figs. 9.60–9.72. The biceps brachii muscle is located on the anterior surface of the humerus and acts as a strong flexor of the forearm. The biceps brachii muscle is named “biceps” because of its two expanded heads of proximal attachment (long and short). The tendon of the long head arises from the supraglenoid tubercle and courses through the intertubercular (bicipital) groove to merge with the tendon from the short head. The short head of

Acromion process

Clavicle Coracoid process

Greater tubercle

S

Clavicle

Coracoid process

Humeral head Greater tubercle

Lesser tubercle

Lesser tubercle Humerus

Scapula

R

Scapula

L

R

L

Biceps brachii muscle:

Coracobrachialis muscle

Short head Long head Lateral epicondyle Radial head Radius Radial tuberosity

Medial epicondyle Aponeurosis of biceps brachii muscle

Brachialis muscle Lateral epicondyle

Medial epicondyle

Radius

Ulnar tuberosity

Ulnar tuberosity I

Ulna

FIG. 9.60  Anterior view of biceps brachii muscle.

Ulna I

FIG. 9.61  Anterior view of coracobrachialis and brachialis muscles.

600

CHAPTER 9  Upper Extremity $

A

%LFHSVEUDFKLLPXVFOH &HSKDOLFYHLQ &RUDFREUDFKLDOLV PXVFOH +XPHUXV 0XVFXORFXWDQHRXV QHUYH

Biceps brachii muscle Brachial artery Median nerve

0HGLDQQHUYH

0HGLDOFXWDQHRXV QHUYHRIIRUHDUP %DVLOLFYHLQ 5 %UDFKLDODUWHU\ 8OQDUQHUYH

Musculocutaneous nerve Cephalic vein Humerus

Basilic vein Brachialis muscle

Medial cutaneous nerve of forearm

/ R

3URIXQGD EUDFKLLDUWHU\

Radial nerve

Superior ulnar collateral artery

Profunda brachii artery

Ulnar nerve

5DGLDOQHUYH

7ULFHSVEUDFKLL PXVFOHPHGLDOKHDG

Nerve to anconeus

Triceps brachii muscle (medial head)

'HOWRLGPXVFOH 7ULFHSVEUDFKLL PXVFOH ORQJKHDG 7ULFHSVEUDFKLL PXVFOH ODWHUDOKHDG

Triceps brachii muscle (long head)

3

L

Profunda brachii artery Triceps brachii muscle (lateral head) P

FIG. 9.62  Axial view of humerus, proximal one-third, left arm.

FIG. 9.63  Axial view of humerus, midhumerus, left arm. $

%UDFKLDODUWHU\

%LFHSVEUDFKLL PXVFOH

0HGLDQQHUYH %UDFKLDOLVPXVFOH 0HGLDO FXWDQHRXV QHUYHRI IRUHDUP 5

0XVFXORFXWDQHRXV QHUYH &HSKDOLFYHLQ %UDFKLRUDGLDOLV PXVFOH 3RVWHULRU FXWDQHRXVQHUYH RIIRUHDUP 5DGLDOQHUYH

%DVLOLFYHLQ

5DGLDOFROODWHUDO / DUWHULHV ([WHQVRUFDUSL UDGLDOLVORQJXV PXVFOH

6XSHULRU XOQDU FROODWHUDO DUWHU\ 8OQDUQHUYH ,QIHULRUXOQDU FROODWHUDODUWHU\

+XPHUXV

0LGGOHFROODWHUDO EUDQFKRISURIXQGD EUDFKLLDUWHU\

7ULFHSVEUDFKLL PXVFOH 3

FIG. 9.64  Axial view of humerus, distal one-third, left arm. the biceps brachii muscle originates from the coracoid process and joins with the long head to create the biceps brachii muscle, which terminates in two tendons. The stronger tendon inserts on the radial tuberosity, and the other tendon creates the bicipital aponeurosis, which radiates into the fascia of the forearm (Fig. 9.60). The brachialis muscle originates from the anterior surface of the distal humerus and covers the anterior surface of the elbow joint before inserting on the ulnar tuberosity and the coronoid process. The brachialis

muscle is considered to be the most important flexor muscle of the elbow joint (Fig. 9.61). The coracobrachialis muscle is a long, narrow muscle located in the superomedial aspect of the arm. It arises from the coracoid process along with the short head of the biceps brachii and extends to insert on the medial surface of the humerus. The primary action of the coracobrachialis muscle is to assist with flexion and adduction of the arm, but it also helps hold the head of the humerus within the joint capsule (Figs. 9.61).

CHAPTER 9  Upper Extremity Biceps brachii muscle

Cephalic vein

A

Humerus Deltoid muscle

Coracobrachialis muscle

Radial nerve

Brachial artery

Triceps brachii muscle (lateral head)

Median nerve

R

L

Ulnar nerve Brachial vein

Triceps brachii muscle (long head)

Triceps brachii muscle (medial head)

P

FIG. 9.65  Axial, T1-weighted MRI of proximal humerus, left arm.

Brachial artery

Biceps brachii muscle (long head) A

Cephalic vein

Biceps brachii muscle (short head)

Brachialis muscle Radial nerve

Median nerve

Humerus R

L Triceps brachii muscle (lateral head)

Brachial vein Basilic artery and vein

Triceps brachii muscle (medial head)

Ulnar nerve

Triceps brachii muscle (long head)

P

FIG. 9.66  Axial, T1-weighted MRI of midhumerus, left arm.

601

CHAPTER 9  Upper Extremity

602

Biceps brachii muscle (short head)

A

Brachialis muscle

Brachial artery

Brachioradialis muscle

Brachial vein Radial nerve

Median nerve R

L

Medial condyle of humerus

Extensor carpi radialis longus muscle

Ulnar nerve

Lateral condyle of humerus

Triceps brachii muscle (medial head) Triceps brachii tendon

P

Triceps brachii muscle (lateral head)

FIG. 9.67  Axial, T1-weighted MRI of distal humerus, left arm. Pectoralis minor muscle

A

Pectoralis major muscle

Rib

Biceps brachii muscle

R

L

Humerus Deltoid muscle

Intercostal muscle

Teres major muscle Triceps brachii muscle (lateral head)

Serratus anterior muscle

Triceps brachii muscle (long head)

Latissimus dorsi muscle

P

Teres minor muscle

FIG. 9.68  Axial CT of proximal humerus, right arm.

Scapula Subscapularis muscle

CHAPTER 9  Upper Extremity Cephalic vein

Biceps brachii muscle

A

Brachioradialis muscle Median nerve Radial nerve

Brachial artery Brachial vein R

L

Profunda brachii artery

Basilic vein

Humerus

Brachialis muscle

P

Triceps brachii muscle lateral head

Triceps brachii muscle long head

FIG. 9.69  Axial CT of midhumerus, right arm.

3URIXQGD EUDFKLLDUWHU\

5DGLDO QHUYH

$

&HSKDOLF YHLQ

%UDFKLDOLV PXVFOH

%LFHSVEUDFKLL PXVFOHVKRUWKHDG

%UDFKLRUDGLDOLV PXVFOH ([WHQVRUFDUSL UDGLDOLVORQJXV PXVFOH

%UDFKLDODUWHU\ %UDFKLDOYHLQ

5

/

0HGLDQQHUYH ([WHQVRUFDUSL UDGLDOLVPXVFOH %DVLOLFYHLQ

/DWHUDO HSLFRQG\OH

0HGLDO HSLFRQG\OH

7ULFHSVEUDFKLLPXVFOH

3

8OQDUQHUYH

FIG. 9.70  Axial CT of distal humerus, right arm.

603

604

CHAPTER 9  Upper Extremity S Supraspinatus tendon

Acromion Infraspinatus muscle

Biceps brachii tendon (long head)

Posterior humeral circumflex artery Teres minor muscle

Deltoid muscle A

P

Coracobrachialis muscle

Teres major muscle

Biceps brachii muscle

Axillary nerve Latissimus dorsi muscle

Basilic vein I

FIG. 9.71  Sagittal, T1-weighted MRI of humerus.

S Supraspinatus tendon

Deltoid muscle

Infraspinatus muscle Teres minor muscle Deltoid muscle

Axillary nerve A

P Posterior humeral circumflex artery Triceps brachii muscle (long head)

Biceps brachii muscle

Triceps brachii muscle (lateral head)

Brachialis muscle I

FIG. 9.72  Sagittal, T1-weighted MRI of humerus with biceps brachii muscle.

CHAPTER 9  Upper Extremity Scapular spine S

Acromion process

Humeral head

605

S

Lateral epicondyle

Humerus

Infraglenoid tubercle of the scapula

Olecranon process of ulna Anconeus muscle

L

R

Supinator muscle

Triceps brachii muscle (lateral head)

Scapula

Abductor pollicis longus muscle

Ulna

Extensor pollicis longus muscle

Triceps brachii muscle (long head)

Extensor indicis muscle

Lateral epicondyle of humerus

Extensor pollicis brevis muscle

Triceps brachii muscle (medial head) Radius

Ulna Olecranon process of ulna

I

Interossei muscles

FIG. 9.73  Posterior view of triceps brachii muscle.

I

FIG. 9.74  Posterior view of anconeus muscle.

TABLE 9.4

Muscles of the Upper Arm

Muscle

Proximal Attachment

Distal Attachment

Primary Action

Biceps brachii

Long head—supraglenoid tubercle of scapula Short head—coracoid process of scapula Distal humerus Coracoid process of scapula

Bicipital aponeurosis and radial tuberosity Ulnar tuberosity and coronoid process Middle third medial surface of humerus

Supinates and flexes forearm

Long head—infraglenoid tubercle of scapula Medial head—posterior surface of humerus below radial groove Lateral head—posterior surface of humerus below greater tubercle Lateral epicondyle of humerus

Proximal end of olecranon process of ulna

Brachialis Coracobrachialis Triceps brachii

Anconeus

Dorsal Group  Triceps brachii Anconeus

The muscles of the dorsal group are shown in Figs. 9.62–9.84. The triceps brachii muscle is located on the posterior surface of the humerus and is the main extensor of the forearm. It is named triceps because of its three heads of proximal attachment (long, medial, and lateral). The long head of the triceps originates from the infraglenoid tubercle of the scapula, the medial head originates from the entire

Olecranon process of ulna

Flexion of elbow joint Assists in flexing and adducting the arm Chief extensor of forearm, long head steadies head of humerus if abducted Assists triceps brachii in extension of elbow

dorsal surface of the humerus distal to the radial groove, and the lateral head arises from the dorsal surface and lateral intermuscular septum of the humerus. All three heads join in a common tendon that inserts on the olecranon process of the ulna and the posterior joint capsule (Fig. 9.73). The small, triangular anconeus muscle originates on the lateral epicondyle of the humerus and crosses obliquely to insert on the dorsal surface of the olecranon process, close to the tendon of the triceps brachii (Fig. 9.74). It assists the triceps brachii in extension and also provides dynamic joint stability to the lateral joint capsule.

CHAPTER 9  Upper Extremity

606

ELBOW The elbow is a complex hinge-pivot joint created by the articulations of the humerus, radius, and ulna. All three articulations communicate with each other within a single joint capsule. The radius and ulna are the bones *UHDWHUWXEHUFOH

of the forearm, with the radius located on the lateral side. The radioulnar and radiohumeral articulations create the pivot joint that aids in supination and pronation of the elbow. The radiohumeral and ulnohumeral articulations form the hinge joint that allows for flexion and extension (Figs. 9.75–9.78).

+HDGRI KXPHUXV

/HVVHUWXEHUFOH

$QDWRPLFQHFN 6XUJLFDOQHFN

,QWHUWXEHUFXODU JURRYH

5DGLDOJURRYH 'HOWRLGWXEHURVLW\ %RG\VKDIW 0HGLDO VXSUDFRQG\ODUULGJH &RURQRLGIRVVD

/DWHUDO VXSUDFRQG\ODUULGJH

2OHFUDQRQIRVVD *URRYHIRUXOQDUQHUYH

5DGLDOIRVVD

0HGLDOHSLFRQG\OH

&DSLWHOOXP

/DWHUDOHSLFRQG\OH

0HGLDOFRQG\OH

/DWHUDOFRQG\OH

7URFKOHD

$QWHULRU

FIG. 9.75  Humerus. Left, Anterior view.

3RVWHULRU

Right, Posterior view.

6

2OHFUDQRQ SURFHVV

/DWHUDO HSLFRQG\OH

0HGLDO HSLFRQG\OH

&DSLWHOOXP 5

/

7URFKOHD

5DGLRKXPHUDO DUWLFXODWLRQ 5DGLDO KHDG

8OQRKXPHUDO DUWLFXODWLRQ

&RURQRLG SURFHVV

,

5DGLDO QRWFK

FIG. 9.76  Coronal, T1-weighted MRI of left elbow.

5DGLDO WXEHURVLW\

5DGLRXOQDU DUWLFXODWLRQ

CHAPTER 9  Upper Extremity

607

Olecranon process Radial notch

Trochlear notch Coronoid process

Head Neck

Head of radius Neck of radius

Ulnar tuberosity Proximal radioulnar joint

Radial tuberosity

Interosseous membrane Radius

Ulna

Radius

Ulnar notch Head of ulna

Styloid process of radius

Styloid process of ulna

Carpal Distal articular surface radioulnar joint

FIG. 9.77  Radius and ulna. Left, Anterior view. Right, Posterior view.

Anterior view

Styloid process of radius Radial dorsal tubercle (Lister’s tubercle) Posterior view

Olecranon process Trochlear notch

Humerus

B Medial epicondyle of humerus

A

Coronoid process

Coronoid fossa

Radial notch

Capitellum

Ulna

Trochlea

Semilunar notch

Radial head

Coronoid process

Ulnar tuberosity Radial tuberosity Radius

Ulnar notch of radius

C Ulna

Radius Ulna

Head of ulna Interosseous membrane

Radial styloid process

Ulnar styloid process Articulation for scaphoid

Articulation for lunate

FIG. 9.78  Anatomy of the elbow and distal forearm. (A) Elbow in medial view. (B) Proximal ulna in lateral view. (C) Distal radius and ulna.

608

CHAPTER 9  Upper Extremity if viewed in the horizontal plane. The shape of the trochlea helps keep the ulna in position during flexion between the humerus and radius (Figs. 9.75, 9.76, and 9.78A–9.81).

Bony Anatomy Distal Humerus.  The distal portion of the humerus

has two distinct prominences termed the medial and lateral condyles, with associated epicondyles, which provide attachment sites for tendons and ligaments (Fig. 9.75). The medial epicondyle serves as the site of origin for the common flexor tendon, pronator teres muscle, and medial collateral ligament, whereas the lateral epicondyle serves as the attachment site for the common extensor tendon, supinator muscle, and lateral collateral ligament. Just lateral to the medial epicondyle, along its posterior surface, is a shallow groove containing the ulnar nerve. Two depressions located on the distal humerus are the anterior coronoid fossa and the deep posterior olecranon fossa. These depressions accommodate the coronoid and olecranon processes of the proximal ulna (Figs. 9.75, 9.76, and 9.78). The distal humerus has two cartilage-covered articular surfaces—the capitellum and the trochlea—for articulation with the radius and ulna (Fig. 9.76). The lateral of the two surfaces is the capitellum, a rounded projection that articulates with the concave surface of the radial head. The trochlea is more medial and has the appearance of an hourglass

Radius: Proximal.  The radius is a long, slender bone

with a proximal portion that consists of the radial head, neck, and tuberosity. The radial head has a flat cartilagecovered depression or fossa (fovea of the radius) that articulates with the capitellum of the humerus. In addition, the articular circumference of the radial head articulates against the radial notch of the ulna during supination and pronation. The radial head is attached to the body of the radius by the narrow radial neck. Located at the distal portion of the neck on the medial side of the radius is a roughened projection termed the radial tuber­ osity. The radial tuberosity serves as the attachment point for the biceps brachii muscle (Figs. 9.77, 9.78A and B, and 9.79).

Because of its superficial location, the ulnar nerve is the most frequently injured nerve of the body.

6

7ULFHSV EUDFKLL PXVFOH

%LFHSV EUDFKLL PXVFOH

3RVWHULRU IDWSDG

%UDFKLDOLV PXVFOH

5DGLDO IRVVD

$QWHULRU IDWSDG $

3 $QFRQHXV PXVFOH

&DSLWHOOXP

5DGLDO QHFN %UDFKLRUDGLDOLV PXVFOH

5DGLDO KHDG 6XSLQDWRU PXVFOH

,

FIG. 9.79  Sagittal, T1-weighted MRI of elbow with proximal radius.

CHAPTER 9  Upper Extremity

Radius: Distal.  The broadened distal end of the radius

includes the cartilage-covered carpal articular surface, the ulnar notch, and the radial styloid process. The car­ pal articular surface articulates with the scaphoid and lunate bones of the wrist. The ulnar notch articulates with the ulna, and the styloid process serves as an attachment site for the extensor pollicis longus and extensor carpi radialis tendons. The dorsal surface of the radius contains several grooves that serve as passages for the extensor tendons. Along with the grooves, a prominent ridge is located on the dorsal surface termed the radial dorsal tubercle, or Lister’s tubercle, a common site for the formation of bony spurs (Figs. 9.77 and 9.78C).

Ulna: Proximal.  The ulna is located medial within the forearm. The proximal ulna consists of the olecranon and coronoid processes and the trochlear and radial

609

notches. The superficial dorsal surface is formed by the hook-shaped olecranon process, which is the attachment site for the triceps brachii muscle. The trochlear notch is a half-moon–shaped concave articular surface that curves around the trochlea of the humerus. This articulation allows for flexion and extension of the elbow. Located on the anterior portion of the distal end of the trochlear notch is a small beaklike process called the coronoid process. Just distal and lateral to the coronoid process is a flattened depression called the radial notch, which is covered by articular cartilage for articulation with the radial head. Immediately distal to the coronoid process is a roughened bony surface termed the ulnar tuberosity. The tendon of the brachialis muscle inserts on both the coronoid process and the ulnar tuberosity (Figs. 9.77, 9.78A and B, 9.80, and 9.81).

6

+XPHUXV 7ULFHSVEUDFKLL PXVFOH

$QWHULRU IDWSDG

3RVWHULRU IDWSDG 7HQGRQRI WULFHSVEUDFKLL PXVFOH

%UDFKLDOLV PXVFOH

2OHFUDQRQ SURFHVV 7URFKOHD $

3

7URFKOHDU QRWFK %LFHSVEUDFKLL WHQGRQ %UDFKLDOLV WHQGRQ

&RURQRLG SURFHVV

8OQD

,

FIG. 9.80  Sagittal, T1-weighted MRI of elbow with proximal ulna.

610

CHAPTER 9  Upper Extremity Humerus

A Olecranon fossa of humerus Lateral epicondyle

R

L

Medial condyle Lateral condyle

P

Medial epicondyle

Olecranon process

FIG. 9.81  Axial CT of left elbow.

Ulna: Distal.  The smaller, distal end of the ulna has

two prominent projections. The larger, rounded projection is an articular eminence termed the head of the ulna. It articulates with the ulnar notch of the radius and the triangular fibrocartilage complex. The small conical projection on the medial surface is called the ulnar styloid process, which serves as the attachment site for the ulnar collateral ligament of the wrist. Another structure that is important in stabilizing and strengthening the connection between the radius and ulna is the interosseous membrane, a strong fibrous sheath stretching between the interosseous borders of both bones (Figs. 9.77 and 9.78C).

Joint Capsule and Fat Pads.  The entire elbow joint

is surrounded by a relatively loose joint capsule that

allows for the movements of flexion and extension. The joint capsule is weaker anteriorly and posteriorly but is reinforced medially and laterally by the strong radial and ulnar collateral ligaments (discussed in the next section). Located within the olecranon and coronoid fossae are fat pads that fill the space between the synovial membrane and joint capsule (Figs. 9.79, 9.80, and 9.82– 9.85). The fat pads help cushion the area where the olecranon and coronoid processes move during flexion and extension of the elbow. There are two clinically important bursae located in the elbow: the olecranon bursa and the bicipitoradial bursa. The olecranon bursa is located within the subcutaneous tissue overlying the olecranon process (Fig. 9.82). The bicipitoradial bursa lies between the insertion of the biceps tendon and the radial tuberosity.

S Triceps brachii muscle Brachialis muscle

Posterior fat pad

Joint capsule Subtendinous olecranon bursa

Anterior fat pad A

Olecranon process P

Trochlea of humerus Synovial membrane

Olecranon bursa

Coronoid process of ulna

Subcutaneous fat

Ulna

I

FIG. 9.82  Sagittal view of elbow at midjoint.

CHAPTER 9  Upper Extremity Humerus

S

Coronoid fossa

Medial epicondyle

Common flexor tendon

Lateral epicondyle

R

L Ulnar collateral ligament

Common extensor tendon

Coronoid process

Radial collateral ligament

Radial notch of ulna

Radial head

I

FIG. 9.83  Coronal, T2-weighted MRI of right elbow, post-arthrogram.

Radial notch Brachioradialis Joint capsule muscle

Biceps brachii tendon

A

Brachialis muscle and tendon

Pronator teres muscle Palmaris longus muscle

Annular ligament

Flexor digitorum superficialis muscle

Extensor carpi radialis longus muscle

Ulna R

L Ulnar nerve

Extensor digitorum muscle

Flexor carpi ulnaris muscle

Common extensor tendon

Radial head

Anconeus muscle

Ulnar collateral ligament

P

Flexor digitorum profundus muscle Olecranon

FIG. 9.84  Axial, T2-weighted MRI of right elbow, post-arthrogram.

611

CHAPTER 9  Upper Extremity

612

A

Anterior fat pad

Brachioradialis muscle

Brachialis muscle

Pronator teres muscle R

L Humerus

P

Posterior fat pad

Triceps brachii muscle

FIG. 9.85  Axial CT of right elbow with fat pads.

Ligaments The stability of the elbow joint primarily depends on the collateral ligaments, which are woven into the lateral portions of the joint capsule. The ulnar (medial) collat­ eral ligament consists of three components: an anterior band, a posterior band, and a transverse band (ligament

Humerus Articular capsule Annular ligament

Transverse band Anterior band Posterior band

Radius

Ulna Ulnar (medial) collateral ligament

FIG. 9.86  Lateral view of ulnar collateral ligament.

of Cooper) (Figs. 9.83–9.88). The anterior band, which is the strongest, extends from the medial epicondyle of the humerus to the medial aspect of the coronoid process. The posterior band originates along with the anterior band from the medial epicondyle of the humerus and inserts on the medial aspect of the olecranon process, forming a triangular plate. The weaker transverse band stretches between the medial surfaces of the coronoid and olecranon processes to unite the anterior and posterior bands. The ulnar collateral ligament forms the floor of the cubital tunnel for passage of the ulnar nerve (Figs. 9.86–9.89). Reinforcing the lateral side is the triangular radial (lateral) collateral ligament. The radial collateral ligament originates from the lateral epicondyle of the humerus, adjacent to and beneath the common extensor tendons, and spreads distally to insert on the annular ligament and the anterior and posterior margins of the radial notch of the ulna (Figs. 9.88 and 9.90). The an­ nular ligament forms a fibrous ring that encircles the radial head and attaches to the anterior and posterior margins of the radial notch. It also has a narrow portion that tightens around the radial neck to prevent inferior displacement of the radius (Figs. 9.84, 9.86, and 9.90–9.92). The annular ligament is considered a key structure in the proximal radioulnar joint, allowing the head of the radius to rotate freely.

CHAPTER 9  Upper Extremity

613

Humerus

Radial head

Anterior band of ulnar (medial) collateral ligament

Medial epicondyle of ulna

Cubital tunnel Fascial sheath continuous with flexor pronator fascia

Ulnar nerve

FIG. 9.87  Cubital tunnel.

Humerus

Brachialis muscle

S

Triceps brachii muscle

Radial (lateral) collateral ligament Pronator teres muscle

R

L Radial head

Ulnar (medial) collateral ligament

Flexor digitorum superficialis muscle

I

Supinator muscle

FIG. 9.88  Coronal, T1-weighted MRI of left elbow with collateral ligaments.

Extensor carpi radialis longus muscle

614

CHAPTER 9  Upper Extremity Pronator teres muscle

Biceps brachii muscle

Brachialis muscle

A

Brachioradialis muscle

R

L

Anconeus muscle Medial epicondyle

Olecranon process

Cubital tunnel

Ulnar nerve

P

Anterior band of ulnar (medial) collateral ligament

FIG. 9.89  Axial CT of left elbow with ulnar nerve and cubital tunnel.

Humerus

Annular ligament Radial tuberosity

Ulna

Radial (lateral) collateral ligament

Joint capsule

FIG. 9.90  Lateral view of radial (lateral) collateral ligament.

CHAPTER 9  Upper Extremity Pronator teres muscle

A

Brachialis muscle

Biceps brachii tendon Brachioradialis muscle Annular ligament R

L

Radial head

Flexor carpi radialis muscle

Flexor carpi ulnaris muscle

Flexor digitorum profundus muscle

P

Olecranon process

Radial notch

Anconeus muscle

FIG. 9.91  Axial, T1-weighted MRI of left elbow with annular ligament.

Pronator teres muscle

Tendon of biceps brachii muscle

A

Brachialis muscle

Brachioradialis muscle

Annular ligament Radial head Anconeus muscle

R Flexor carpi radialis muscle

L Flexor carpi ulnaris muscle

Brachialis tendon

P

Flexor Ulna digitorum profundus muscle

Radial notch

FIG. 9.92  Axial CT of left elbow with annular ligament.

615

616

CHAPTER 9  Upper Extremity

Muscles of the Forearm One method to classify the muscles of the forearm is to use the radius, ulna, and interosseous membrane to divide them into a ventral group (the flexors) and a dorsal group (the extensors). The two groups can be further divided into superficial and deep muscles. The muscles of the forearm are described in Table 9.5.

TABLE 9.5

Ventral Group—Superficial Muscles  Pronator teres Flexor carpi radialis Palmaris longus Flexor carpi ulnaris Flexor digitorum superficialis

Muscles of the Forearm

Muscle

Origin

Insertion

Primary Actions

Lateral surface of radius, midshaft

Pronates and flexes forearm

Base of second metacarpal Palmar aponeurosis Pisiform, hook of hamate, fifth metacarpal Lateral sides of middle phalanges of second to fifth fingers

Flexes and abducts hand Flexes wrist Flexes wrist and adducts hand

Bases of distal phalanges of second through fifth digits

Flexes distal phalanges of fourth or fifth finger at distal interphalangeal joint Flexes phalanges of thumb

Ventral-Superficial Group Pronator teres Flexor carpi radialis Palmaris longus Flexor carpi ulnaris Flexor digitorum superficialis

Humeral head—common flexor tendon Ulnar head—near coronoid process of ulna Common flexor tendon Common flexor tendon Humeral head—common flexor tendon Ulnar head—olecranon process Humeral head—common flexor tendon Ulnar head—coronoid process Radial head—anterior surface of proximal half of radius

Ventral-Deep Group Flexor digitorum Anterior surface of proximal ulna profundus Flexor pollicis longus Pronator quadratus

Anterior surface of radius and interosseous membrane Anterior and radial aspects of distal ulna

Dorsal-Superficial Group Brachioradialis Proximal two-thirds of supracondylar ridge of humerus Extensor carpi radialis Lateral supracondylar ridge of humerus longus Extensor carpi radialis Common extensor tendon brevis Extensor digitorum Common extensor tendon

Base of distal phalanx of thumb Anterior surface of distal radius

Distal radius, base of styloid process on lateral surface Dorsal aspect base of second metacarpal Dorsal aspect base of third metacarpal Extensor expansions of second to fifth digits Proximal phalanx of fifth digit

Extensor digiti minimi

Common extensor tendon

Extensor carpi ulnaris

Common extensor tendon

Dorsal aspect of base of fifth metacarpal

Posterior surface of proximal ulna, radius, and interosseous membrane Posterior surface of distal third of radius and ulna and interosseous membrane Posterior surface of middle third of ulna and interosseous membrane Posterior surface of distal third of ulna and interosseous membrane Oblique head: lateral epicondyle of humerus, radial collateral ligament Transverse head: supinator crest of ulna

Base of first metacarpal

Dorsal-Deep Group Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor indicis Supinator

Dorsal aspect of base of proximal phalanx of first digit Dorsal aspect of base of distal phalanx of first digit Extensor expansion of second digit Lateral, posterior, and anterior surfaces of proximal radius

Flexes middle and proximal phalanges of second to fifth fingers

Pronates forearm

Weak forearm flexion, assists with pronation and supination Extends and abducts hand at wrist joint Extends and abducts hand at wrist joint Extends second to fifth digits at metacarpophalangeal joints Extends fifth finger at metacarpophalangeal joint Extends and adducts hand at wrist joint Abducts thumb and extends thumb at carpometacarpal joint Extends proximal phalanx of thumb at metacarpophalangeal joint Extends distal phalanx of thumb at interphalangeal joint Supinates forearm Supinates forearm

CHAPTER 9  Upper Extremity

617

The flexor carpi ulnaris muscle is the most medial of the superficial muscles located in the anterior portion of the forearm. It has two heads: The humeral head originates from the common flexor tendon, and the ulnar head originates from the olecranon process. It inserts onto the pisiform, hook of the hamate, and fifth metacarpal and acts to flex and adduct (ulnar deviation) the hand at the wrist joint (Fig. 9.93). The flexor digitorum superficialis muscle is the largest muscle of the superficial muscles in the forearm. It arises from three heads: the humeral head from the common flexor tendon, the ulnar head from the coronoid process, and the radial head from the anterior surface of the proximal half of the radius. Just before reaching the flexor retinaculum, the muscle divides into four tendons that share a common synovial sheath through the carpal tunnel. After passing under the flexor retinaculum, the tendons insert on the lateral sides of the middle phalanges of the second to fifth digits. The flexor digitorum superficialis muscle is a strong flexor of the middle and proximal phalanges of the second through fifth digits (Fig. 9.107).

All five of the superficial muscles in the ventral group have an origin from the common flexor tendon off the medial epicondyle of the humerus. These muscles are shown in Figs. 9.93–9.107. The pronator teres muscle has two heads of origin. Its humeral head originates from the common flexor tendon, whereas the ulnar head originates near the coronoid process of the ulna. The pronator teres muscle courses obliquely before inserting on the lateral surface of the radius at midshaft. It works in conjunction with the pronator quadratus muscle to pronate the forearm (Fig. 9.93). The flexor carpi radialis muscle originates from the common flexor tendon and is located medial to the pronator teres. Its tendon passes through the carpal tunnel of the flexor retinaculum before inserting on the palmar surface of the base of the second metacarpal. Its actions include flexion and radial deviation of the hand at the wrist joint (Fig. 9.93). The palmaris longus muscle originates from the common flexor tendon and passes superficial to the flexor retinaculum to merge with the palmar aponeurosis. It acts to flex the hand and tighten the palmar aponeurosis (Fig. 9.93). S Brachial artery

Biceps brachii muscle

Median nerve

Brachialis muscle Radial nerve Posterior interosseous nerve

Common flexor tendon Bicipital aponeurosis

Ulnar artery

Pronator teres muscle

Supinator muscle Radial artery

Flexor carpi radialis muscle

Brachioradialis muscle

Palmaris longus muscle

Flexor digitorum superficialis muscle (radial head)

Flexor carpi ulnaris muscle

Abductor pollicis longus muscle

Flexor digitorum superficialis muscle

Radial artery

Ulnar artery

Median nerve

Ulnar nerve

Flexor retinaculum

Guyon canal

Flexor pollicis brevis muscle

Palmaris brevis muscle

Adductor pollicis muscle

Palmar aponeurosis

I

FIG. 9.93  Anterior view of superficial flexor muscles of forearm.

618

CHAPTER 9  Upper Extremity

Median nerve Pronator teres

Brachialis artery Flexor carpi radialis

A

Cephalic vein

Palmaris longus

Radial artery Brachioradialis Superficial branch of radial nerve

Basilic vein Flexor digitorum superficialis

R

Extensor carpi radialis longus

L

Flexor carpi ulnaris Ulnar nerve

Supinator

Flexor digitorum profundus

Radius

Ulna

Extensor carpi radialis brevis Deep branch of radial nerve Extensor digitorum

P

Extensor carpi ulnaris Common interosseous artery and vein

Extensor digiti minimi

FIG. 9.94  Axial view of forearm, proximal one-third, right arm. Flexor carpi radialis Palmaris longus

Median nerve Cephalic vein Radial artery

Flexor digitorum superficialis Ulnar artery

A

Ulnar nerve

Brachioradialis

Flexor carpi ulnaris

Superficial branch of radial nerve Pronator teres Extensor carpi radialis longus

L

R

Flexor digitorum profundus Basilic vein

Ulna Extensor pollicis longus and extensor indicis

Flexor pollicis longus Extensor carpi radialis brevis Radius

Extensor carpi ulnaris

Abductor pollicis longus

P

Extensor digitorum

Interosseous membrane Extensor digiti minimi

Extensor pollicis brevis

FIG. 9.95  Axial view of forearm, mid-forearm, right arm.

Median nerve

Palmaris longus tendon Flexor digitorum superficialis tendons

Flexor pollicis longus tendon Flexor carpi radialis tendon

Flexor retinaculum Ulnar artery Flexor carpi ulnaris tendon

A

Radial artery Pronator quadratus muscle

Ulnar nerve

Abductor pollicis longus tendon L

Basilic vein Extensor pollicis brevis tendon

Flexor digitorum profundus tendons Articular cartilage

R

Ulna

Brachioradialis tendon

Extensor carpi ulnaris tendon

Radius Extensor carpi radialis longus tendon

P

Extensor carpi radialis brevis tendon

Extensor digiti minimi tendon Extensor digitorum tendons

Extensor pollicis longus tendon

FIG. 9.96  Axial view of forearm, distal one-third, right arm.

CHAPTER 9  Upper Extremity Extensor carpi radialis longus muscle Radius

Brachioradialis muscle

Cephalic vein Pronator Median teres nerve muscle A

Flexor digitorum superficialis muscle

Palmaris longus muscle

R

L

Extensor radialis brevis muscle

Anconeus Supinator muscle muscle

Ulna

P

Flexor Ulnar Flexor Ulnar digitorum artery carpi nerve profundus ulnaris muscle muscle

FIG. 9.97  Axial, T1-weighted MRI of proximal forearm muscles, right arm.

Extensor carpi Radial Flexor Flexor Flexor Ulnar radialis artery carpi digitorum digitorum artery Cephalic longus and radialis superficialis profundus and vein muscle nerve muscle muscle muscle nerve A

Flexor carpi ulnaris muscle

Flexor pollicis longus muscle Radius R

L Abductor pollicis longus muscle

Extensor carpi radialis brevis muscle

Basilic vein

Extensor digitorum muscle Interosseous Extensor membrane digiti minimi muscle

P

Extensor carpi ulnaris muscle

Extensor pollicis longus muscle

FIG. 9.98  Axial, T1-weighted MRI of mid-forearm muscles, right arm.

Ulna

619

620

CHAPTER 9  Upper Extremity

Median nerve

Palmaris longus tendon

Flexor digitorum superficialis tendons A

Ulnar artery and vein

Ulnar nerve

Flexor carpi radialis tendon

Flexor carpi ulnaris muscle and tendon

Flexor pollicis longus tendon

Flexor digitorum profundus tendons

Radial artery R

L Ulna

Abductor pollicis longus tendon

Extensor carpi ulnaris tendon

Extensor pollicis brevis tendon

Radius

Extensor carpi radialis longus tendon Lister’s Extensor Extensor carpi radialis tubercle pollicis brevis tendon longus tendon

P

Extensor digitorum and indicis tendons

Extensor digiti minimi tendon

FIG. 9.99  Axial, T1-weighted MRI of distal forearm, right arm.

Pronator teres muscle

Median nerve

Basilic vein

A

Brachial artery

Biceps tendon

Brachioradialis muscle

Anterior ulnar recurrent artery Flexor carpi radialis muscle

Brachialis muscle and tendon

Extensor carpi radialis longus muscle

R

L Extensor carpi radialis brevis muscle

Flexor digitorum superficialis muscle

Radius

Ulnar nerve Flexor digitorum profundus muscle

Ulna

P

Anconeus muscle

Supinator muscle

FIG. 9.100  Axial CT of proximal forearm muscles, left arm.

CHAPTER 9  Upper Extremity Brachioradialis muscle

A

Cephalic vein

Radial artery

Extensor carpi radialis longus

Flexor carpi radialis muscle Pronator teres muscle

Extensor carpi radialis brevis muscle Cephalic vein

Median nerve R

L

Extensor digitorum muscle

Flexor digitorum superficialis muscle

Supinator muscle

Ulnar nerve

Flexor carpi ulnaris muscle

Extensor carpi ulnaris muscle Anconeus muscle

Ulna

P

Basilic vein

Flexor digitorum profundus muscle

FIG. 9.101  Axial CT of mid-forearm muscles, left arm.

Flexor digitorum profundus tendons

Flexor digitorum superficialis tendons A

Median nerve

Flexor pollicis longus tendon

Flexor carpi radialis tendon

Flexor carpi ulnaris muscle and tendon

Pronator quadratus muscle Radial artery

Ulnar artery Ulnar nerve Basilic vein

Abductor pollicis longus tendon Cephalic vein R

L Extensor pollicis brevis tendon

Ulna

Extensor carpi radialis longus tendon

Extensor carpi ulnaris tendon

Extensor carpi radialis brevis tendon Extensor digiti minimi tendon

621

Extensor digitorum and indicis tendons

P

Extensor pollicis Radial (Lister’s) longus tendon tubercle

FIG. 9.102  Axial CT of distal forearm, left arm.

CHAPTER 9  Upper Extremity

622

S

Biceps brachii muscle Brachialis muscle

Brachioradialis muscle

Biceps brachii tendon R

L Extensor carpi radialis longus muscle

Pronator teres muscle

Flexor carpi radialis muscle

Brachial artery I

FIG. 9.103  Coronal, T1-weighted MRI of brachioradialis muscle, left arm. S

Humerus

Pronator teres muscle

Extensor carpi radialis longus muscle

Ulnar (medial) collateral ligament

L Radial (lateral) collateral ligament

R Coronoid process

Radial head

Brachialis muscle Palmaris longus muscle

Supinator muscle Radial tuberosity Flexor carpi radialis muscle

I

FIG. 9.104  Coronal, T1-weighted MRI of forearm muscles, left arm.

CHAPTER 9  Upper Extremity

623

S Posterior fat pad Humerus Triceps brachii tendon

Biceps brachii muscle Anterior fat pad

Olecranon process A

P

Brachialis muscle

Coronoid process

Ulna

Flexor digitorum profundus muscle

Pronator teres muscle I

FIG. 9.105  Sagittal, T1-weighted MRI of forearm muscles.

S Triceps brachii muscle

Brachioradialis muscle

Extensor carpi radialis longus muscle A

P Common extensor tendon Radial head

Extensor carpi radialis brevis muscle

Extensor digitorum muscle

I

FIG. 9.106  Sagittal, T1-weighted MRI of forearm with common extensor tendon.

624

CHAPTER 9  Upper Extremity

Ventral Group—Deep Muscles  Flexor digitorum profundus Flexor pollicis longus Pronator quadratus

The deep muscles of the ventral group are shown in Figs. 9.94–9.107. The flexor digitorum profundus muscle is a long, thick muscle responsible for flexing the distal interphalangeal joints of the fingers. It originates from the anterior surface of the proximal ulna and extends medially to the interosseous membrane. Similar to the flexor digitorum superficialis muscle, the flexor digitorum profundus divides into four tendons before reaching the flexor retinaculum. The four tendons pass deep in the carpal tunnel and continue distally to insert on the distal phalanges, where they pair up with the flexor digitorum superficialis tendons to provide flexion of the middle and

proximal phalanges of the second through fifth digits (Fig. 9.107B). The flexor pollicis longus muscle arises from the anterior surface of the radius and adjacent interosseous membrane and runs lateral to the flexor digitorum profundus to cover the anterior aspect of the radius. After passing through the carpal tunnel, the flexor pollicis longus tendon runs between the flexor pollicis brevis and adductor pollicis brevis muscles to insert at the base of the first distal phalanx to provide flexion to the thumb (Fig. 9.107). The pronator quadratus, a quadrangular muscle, is the deepest muscle in the anterior aspect of the forearm. It arises from the anterior and radial aspect of the distal ulna and passes transversely to insert on the anterior surface of the distal radius. The deep fibers of this muscle help bind the radius and ulna together along with the interosseous membrane. The pronator quadratus is the prime mover in pronation of the forearm (Fig. 9.107).

S Tendon of biceps brachii (cut)

Supinator Extensor carpi radialis longus

Flexor digitorum profundus Flexor digitorum superficialis

Flexor pollicis longus Tendon of flexor carpi radialis (cut) Tendon of brachioradialis (cut)

Pronator quadratus Tendon of flexor carpi ulnaris (cut) Thenar muscles of thumb Tendon of flexor pollicis longus Lumbricals Tendon of flexor digitorum superficialis Tendon of flexor digitorum profundus

A

I

FIG. 9.107  Anterior view of forearm muscles. (A) Superficial muscles. (B) Deep muscles.

B

CHAPTER 9  Upper Extremity

Dorsal Group—Superficial Muscles 

625

carpi ulnaris) arise from a common extensor tendon attached to the lateral epicondyle of the humerus. At the level of the elbow they appear as one structure but become more distinct distally as they insert on various structures about the wrist and hand. The extensor carpi radialis brevis muscle has components that arise from the radial collateral and annular ligaments, as well as the common extensor tendon. It runs along the dorsal surface of the wrist to insert at the base of the third metacarpal and acts to extend and abduct the hand at the wrist joint (Fig. 9.108). The extensor digitorum muscle is the main extensor of the second to fifth digits and occupies much of the posterior surface of the forearm. It arises from the common extensor tendon and divides into four individual tendinous slips just proximal to the wrist. The four tendons run in a single synovial sheath as they pass under the extensor retinaculum. The tendons insert into the extensor expansions of the second through fifth digits, helping to form the extensor hoods (see ligaments of the finger). In addition, small slips of the tendon spread out and run to the bases of the proximal phalanges and to the capsules of the metacarpophalangeal joints. The extensor digitorum muscle extends and spreads the fingers and extends the hand at the wrist joint (Fig. 9.108).

Brachioradialis Extensor carpi radialis longus Extensor carpi radialis brevis Extensor digitorum Extensor digiti minimi Extensor carpi ulnaris

The muscles of the superficial dorsal group are shown in Figs. 9.94–9.106 and 9.108. The brachioradialis is an extensor muscle lying along the lateral border of the forearm. This large muscle arises from the upper two-thirds of the supracondylar ridge of the humerus and attaches distally to the radial styloid process. The brachioradialis muscle flexes the forearm at the elbow and assists with pronation and supination (Figs. 9.93 and 9.108). The extensor carpi radialis longus muscle arises just distal to the brachioradialis muscle on the lower third of the supracondylar ridge of the humerus. It runs posterior and deep to the brachioradialis to insert on the base of the second metacarpal. It acts as an extensor and abductor of the hand at the wrist joint (Fig. 9.108A and B). The other superficial muscles (extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor

S

Brachioradialis Insertion of triceps brachii Anconeus Flexor carpi ulnaris Extensor carpi ulnaris Extensor digiti minimi

Extensor carpi radialis longus

Olecranon process of ulna

Extensor carpi radialis brevis

Anconeus

Extensor digitorum

Supinator

Abductor pollicis longus

Abductor pollicis longus

Extensor pollicis brevis

Extensor pollicis longus

Extensor pollicis longus Extensor indicis

Tendons of extensor carpi radialis brevis and longus Tendons of extensor digitorum

Extensor pollicis brevis Extensor indicis

Interossei

Extensor expansion

A

I

FIG. 9.108  Posterior view of forearm muscles. (A) Superficial muscles. (B) Deep muscles.

B

626

CHAPTER 9  Upper Extremity

The extensor digiti minimi muscle arises from the common extensor tendon and passes under the extensor retinaculum in its own synovial compartment. It then divides into two tendinous slips that insert on the proximal phalanx of the fifth digit to help with extension of the little finger (Fig. 9.108). The extensor carpi ulnaris muscle is a long, slender muscle that arises from the common extensor tendon and runs along the medial and dorsal side of the ulna to insert on the base of the fifth metacarpal. Its main actions include extension of the hand at the wrist joint and adduction of the hand, resulting in ulnar deviation (Fig. 9.108).

aponeurosis of the second digit. It functions with the extensor digitorum muscle to extend the index finger, as if pointing (Fig. 9.108). The supinator muscle originates from two heads: oblique and transverse. The oblique head originates from the lateral epicondyle and collateral ligament, whereas the transverse head originates from the supinator crest of the ulna. Both heads wrap laterally around the proximal radius to insert on the posterolateral and anterior surfaces of the proximal radius to supinate the forearm (Figs. 9.107 and 9.108).

Dorsal Group—Deep Muscles 

The complex anatomy of the wrist and hand provides for a multitude of movements unmatched by any other joint of the body.

Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor indicis Supinator

The deep muscles of the dorsal group consist of four extensors that act on either the first or second digit and include the supinator muscle. These muscles are shown in Figs. 9.94–9.104 and 9.108. The three deep extensors that act on the first digit are the abductor pollicis longus, extensor pollicis brevis, and the extensor pollicis longus muscles. The long, slender abductor pollicis longus muscle arises from the dorsal surfaces of the ulna and radius and from the interosseous membrane. It inserts at the base of the first metacarpal to abduct and extend the thumb (Fig. 9.108). The short extensor pollicis brevis muscle arises from the dorsal surfaces of the ulna and radius and from the interosseous membrane just distal to the abductor pollicis longus muscle. It inserts at the base of the proximal phalanx of the first digit and works together with the abductor pollicis longus muscle to extend and abduct the thumb (Fig. 9.108). The extensor pollicis longus muscle arises from the dorsal surface of the ulna and interosseous membrane just distal to the abductor pollicis longus muscle. After passing through the extensor retinaculum, it crosses over the extensor carpi radialis longus and brevis muscles to insert at the base of the distal phalanx of the first digit. Its main action is to extend the distal phalanx of the first digit, but it can also abduct the hand (Fig. 9.108). The extensor indicis muscle arises from the distal third of the dorsal ulna and the interosseous membrane and runs with the extensor digitorum muscle through the extensor retinaculum to insert on the dorsal

WRIST AND HAND

Bony Anatomy The bony anatomy of the wrist and hand consists of the distal radius and ulna, 8 carpal bones, 5 metacarpals, and 14 phalanges (Fig. 9.109). Both the distal radius and ulna have a conical styloid process that acts as an attachment site for ligaments. The radial styloid process is located on the lateral surface of the radius, whereas the ulnar styloid process is located on the posteromedial side of the ulna. The carpal bones are arranged in proximal and distal rows. Located in the proximal row of carpal bones are the scaphoid (navicular), lunate (semilunar), triquetral (triquetrum), and pisiform bones. The pisiform is considered a sesamoid bone that is embedded in the tendon of the flexor carpi ulnaris. The distal row consists of the trapezium (greater multangular), trape­ zoid (lesser multangular), capitate (os magnum), and hamate (unciform) bones (Figs. 9.109–9.123). The five metacarpals are small tubular bones with a proximal end (base), distal end (head), and middle (body) portion. The 14 phalanges that make up the fingers, like the metacarpals, consist of a proximal (base), distal (head), and middle (body) portion. Each digit consists of three phalanges (proximal, middle, and distal), except for the thumb (first digit), which has only two phalanges (proximal and distal).

A fracture of the hamate may result in a nonunion injury because of the traction of associated muscles. The ulnar nerve runs close to the hook of the hamate and may be injured as well, resulting in decreased grip strength of the hand.

CHAPTER 9  Upper Extremity 3

3

Distal phalanges

4

2

Middle phalanges

2 5

Head Proximal phalanges

Distal phalanx

Distal phalanges Distal interphalangeal joint

4 5

Middle phalanges Proximal interphalangeal joint

Body

Proximal phalanges Metacarpophalangeal joint

Metacarpal head

Base

1

Tubercle

Proximal phalanx

Metacarpals

Trapezoid

Hamate

Capitate

Capitate

Triquetrum Ulnar styloid process

Scaphoid Radial styloid process Lister’s tubercle

Lunate

Trapezoid

Pisiform

Trapezium

Triquetrum Ulnar styloid process

Scaphoid Radial styloid process Radius

Lunate Ulna

Ulna

Radius

Carpometacarpal joint

Hamate hook

Pisiform

Trapezium

Metacarpal base

1

Metacarpals

FIG. 9.109  Bony anatomy of hand and wrist. Left, Dorsal view. Right, Palmar view.

Hamate

Capitate

Capitate

Hamate

Trapezoid

Trapezoid 2

3

4

5

5

4

3

1

2 1

Pisiform

Trapezium

Trapezium

Triquetrum Scaphoid

Lunate

Scaphoid Lunate

FIG. 9.110  Carpal bones. Left, Dorsal view. Right, Palmar view.

Capitate Trapezoid

Triquetrum Hook of hamate Pisiform Flexor retinaculum

Median nerve Carpal tunnel (concave aspect of bones)

FIG. 9.111  Carpal tunnel.

First metacarpal Tubercle of trapezium

627

628

CHAPTER 9  Upper Extremity Fifth metacarpal

Fourth metacarpal

Third metacarpal

Capitate

Second metacarpal First proximal phalanx Metacarpophalangeal joint

Hook of hamate

Sesamoid bones

Hamate

First metacarpal Trapezoid

Triquetral

Carpometacarpal joint

Pisiform

Trapezium Lunate

Scaphoid Styloid process of radius

Styloid process of ulna

Ulna

Radius

FIG. 9.112  3D CT of wrist, palmar aspect.

Fourth metacarpal

Third metacarpal

Second metacarpal

Fifth metacarpal Capitate Hamate Trapezoid Hook of hamate

First metacarpal Trapezium

Pisiform

Tubercle of trapezium

FIG. 9.113  3D CT of carpal tunnel (concave aspect of carpal bones).

CHAPTER 9  Upper Extremity Hamate

Capitate

A

Hook of hamate

Trapezoid

P

Trapezium

First carpoFirst metacarpal metacarpal joint

FIG. 9.114  Axial CT of wrist with distal carpals. Triquetral

Hamate

Capitate

P

A

Pisiform

Scaphoid

FIG. 9.115  Axial CT of wrist, midcarpals. Triquetral

Pisiform

Hamate

P

Capitate

A

FIG. 9.116  Axial CT of wrist with pisiform.

Scaphoid

629

CHAPTER 9  Upper Extremity

630

Hook of hamate

Triquetral

Lunate

P

Scaphoid

Capitate

S

Second metacarpal

Trapezoid

Radius

R

L

A

Pisiform

Pisiform

FIG. 9.117  Axial CT of wrist with proximal carpals.

Fifth metacarpal

Third metacarpal

S

Second metacarpal

Lunate

Radius

I

Capitate

Trapezium

Hamate Trapezoid Intercarpal joints

Pisiform R

L Scaphoid

Triquetral

Radius

Midcarpal joint

I

Scaphoid

FIG. 9.118  Coronal CT reformat of wrist.

Lunate

FIG. 9.119  Coronal CT reformat of wrist with proximal and distal carpals.

Trapezium

CHAPTER 9  Upper Extremity Fifth metacarpal

Fourth metacarpal

S

Third metacarpal

631

Second metacarpal Carpometacarpal joints

Intermetacarpal joint Trapezoid Capitate

Hamate Midcarpal joints R

L Intercarpal joints

Triquetral

Scaphoid Lunate Triangular fibrocartilage complex

Radiocarpal joint Ulna

Distal radioulnar articulation

I

Radius

FIG. 9.120  Coronal CT reformat of wrist with intercarpal joints.

S Second metacarpal

Trapezoid

Scaphoid A

P

Radiocarpal joint Radius

I

FIG. 9.121  Sagittal CT reformat of wrist with scaphoid.

632

CHAPTER 9  Upper Extremity S

Third metacarpal

Capitate

A

P Lunate

Radiocarpal joint Radius

I

FIG. 9.122  Sagittal CT reformat of wrist with lunate.

S

Fourth metacarpal

Hamate

A

P Lunate

Radiocarpal joint Radius

I

FIG. 9.123  Sagittal CT reformat of wrist with hamate.

CHAPTER 9  Upper Extremity

surface of the distal radius and traverses horizontally to insert on the ulnar styloid process. It rotates against the distal surface of the ulnar head during pronation and supination and separates the ulna from the carpal bones (Figs. 9.124–9.126). The proximal surface of the radiocarpal articulation is formed by the articular carpal surface of the radius and the TFCC, whereas the distal surface is formed by the articular surfaces of the scaphoid, lunate, and triquetrum and the interosseous ligaments connecting them (Figs. 9.120–9.124). The midcarpal joint is formed by the articulations between the proximal and distal carpal rows (Figs. 9.119 and 9.124). The articulation between the carpals within each row creates the intercarpal joints (Figs. 9.119, 9.120, and 9.124). The carpometacarpal joints are formed by the articulations between the carpus and the five metacarpals (Fig. 9.120 and 9.124). The carpometacarpal joint of the thumb is an independent joint formed by the articular surfaces of the trapezium and first metacarpal, creating a pure saddle joint. The carpometacarpal articulations of the second to fifth digits are amphiarthrotic joints with little mobility (Figs. 9.114 and 9.124). The intermetacarpal joint exists between the bases of the metacarpals and is reinforced by the palmar and dorsal metacarpal ligaments (Fig. 9.124).

Joints The joints of the wrist and hand are quite complex and consist of the following: distal radioulnar articulation, radiocarpal articulation (proximal joint of hand), midcarpal articulation (distal joint of hand), intercarpal articulations (articulations between proximal and distal carpals), carpometacarpal articulations (between carpals and metacarpals), intermetacarpal articulations (between bases of metacarpals two through five) and interphalangeal joints (between phalanges of each digit) (Figs. 9.119–9.126).

Joints of the Wrist 

Distal radioulnar joint (DRUJ) Radiocarpal joint Midcarpal joint Intercarpal joints Carpometacarpal joints Intermetacarpal joints The distal radioulnar joint is created when the ulnar notch of the radius moves around the articular circumference of the ulna, providing the movements of supination and pronation. The main stabilizing element of the DRUJ is an articular disk called the triangular fibro­ cartilage complex (TFCC). The TFCC is a fan-shaped band of fibrous tissue that originates on the medial

Metacarpal ligaments

Intermetacarpal joint and compartment

I

II

III

IV

Base of fifth metacarpal

V

Common carpometacarpal joint and compartment

First carpometacarpal joint compartment

HAMATE

TRAPEZIUM TRAPEZOID

Radial collateral ligament

Ulnar collateral ligament

CAPITATE

Interosseous ligament

L

A ETR

QU

TRI

SCAPHOID Articular cartilage

Intercarpal ligaments Midcarpal joint (mediocarpal compartment) Intercarpal joints and compartment

LUNATE

Radiocarpal joint and compartment Triangular fibrocartilage complex (TFCC) RADIUS

633

ULNA

Distal radioulnar joint

FIG. 9.124  Coronal cross-section view of wrist joint.

634

CHAPTER 9  Upper Extremity S

Fifth metacarpal

First metacarpal (base) Trapezium

Hamate

Trapezoid

Capitate

Midcarpal joint L

R

Scaphoid Radiocarpal joint Radial collateral ligament

Triquetral Lunate Ulnar collateral ligament

Scapholunate ligament

TFCC Extensor pollicis brevis tendon

Ulna

I Distal radioulnar joint

Radius

FIG. 9.125  Coronal, T2-weighted MRI of wrist with triangular fibrocartilage complex.

Flexor tendons

S

Hook of hamate Trapezium

Fifth metacarpal (base)

Scaphoid Triquetral L

R

Scapholunate ligament Radioscaphocapitate ligament

Lunate TFCC

Radius

Ulnar styloid

Distal radioulnar joint

Ulna

Pronator quadratus muscle

I

FIG. 9.126  Coronal, T2-weighted MRI of wrist with intrinsic ligaments.

CHAPTER 9  Upper Extremity

Joints of the Hand 

635

and an interphalangeal joint, classified as a hinge joint (Figs. 9.109 and 9.112).

Metacarpophalangeal (MCP) Proximal interphalangeal (PIP) Distal interphalangeal (DIP)

Ligaments and Fascia

The articulation of the phalanges of the second through fifth digits creates three interphalangeal joints: the metacarpophalangeal (MCP) joints classified as condyloid joints, proximal interphalangeal (PIP), and distal interphalangeal (DIP). The proximal and distal interphalangeal joints are classified as hinge joints (Fig. 9.109). The first digit, which consists of two phalanges, has just two joints: the MCP joint, classified as a saddle joint,

Numerous extrinsic and intrinsic ligaments provide additional stability to the wrist. The extrinsic ligaments reinforce the joint cavity surrounding the carpal region and include palmar and dorsal radial carpal ligaments, the radial and ulnar collateral ligaments, and the TFCC (Figs. 9.124–9.127). The many articulations between the carpal bones are supported by the intercarpal ligaments or intrinsic ligaments, which connect the carpal bones to

V Pisohamate ligament

H

Triquetrohamate ligament Triquetrocapitate ligament

C

Td

P

I Tm

S L

Scaphocapitate ligament

Ulnocapitate ligament

Radioscaphocapitate ligament

Ulnotriquetral ligament Ulnolunate ligament

Scaphotrapeziumtrapezoid ligament

u

Long radiolunate ligament

r

Short radiolunate ligament

Palmar radioulnar ligament

*Radioscapholunate ligament

V

I

C t

Dorsal intercarpal ligament

S

LT

FIG. 9.127  Extrinsic ligaments of wrist. Top, Palmar view. Bottom, Dorsal view.

Dorsal radiocarpal ligament or Dorsal radiotriquetral ligament

636

CHAPTER 9  Upper Extremity another tunnel called Guyon canal is formed where the ulnar extension of the flexor retinaculum continues over the pisiform and hamate. This creates a potential site for compression of the ulnar nerve (Figs. 9.128, top, and 9.132). The extensor retinaculum (dorsal carpal ligament), located dorsally, is much thinner. It attaches medially to the ulnar styloid process, triquetrum, and pisiform, and laterally to the lateral margin of the radius (Fig. 9.129, right). Along its course, it forms six fibro-osseous tunnels for the passage of the synovial sheaths containing the extensor tendons (Figs. 9.128, bottom; 9.129, right; and 9.130–9.137).

each other (Figs. 9.124–9.126). The configuration of the intrinsic ligaments, metacarpal ligaments, and the TFCC creates five different joint compartments that can be demonstrated by arthrography: (1) compartment of the first carpometacarpal articulation, (2) common carpometacarpal compartment, (3) midcarpal (mediocarpal) compartment, (4) intermetacarpal compartment, and (5) radiocarpal compartment (Fig. 9.124). The carpal tunnel is created by the concave arrangement of the carpal bones (Figs. 9.111, 9.113, and 9.128). A thick ligamentous band called the flexor retinaculum (transverse carpal ligament) stretches across the carpal tunnel to create an enclosure for the passage of tendons and the median nerve. The flexor retinaculum inserts medially on the pisiform and hook of the hamate and spans the wrist to insert laterally on the scaphoid and trapezium (Figs. 9.128–9.137). In addition to the carpal tunnel,

Compression of the median nerve as it passes through the carpal tunnel is called carpal tunnel syndrome. Symptoms include pain and numbness of the fingers supplied by the median nerve.

Base of third metacarpal Tendon of extensor carpi radialis brevis muscle

Tendon of extensor digitorum muscle

Base of second metacarpal

Tendon of extensor indicis muscle

Trapezoid

Capitate

Tendon of extensor carpi radialis longus muscle

Tendons of extensor digitorum muscle Tendon of extensor digiti minimi muscle

Cephalic vein Radial artery

Tendon of extensor carpi ulnaris muscle

Tendon of extensor pollicis longus muscle

Hamate

Tendon of extensor pollicis brevis muscle

Tendons of flexor digitorum profundus muscle

First metacarpal Trapezium

Hypothenar muscles

Tendon of flexor carpi radialis muscle

Ulnar nerve

Tendon of flexor pollicis longus muscle

Guyon canal Ulnar artery

Muscles of thenar eminence

Tendons of flexor digitorum superficialis muscle

Flexor retinaculum

Median nerve Tendons of extensor digitorum muscle

Tendon of extensor pollicis longus muscle

Tendon of extensor digiti muscle V Extensor retinaculum

III

IV

VI

Tendon of extensor carpi ulnaris muscle

II

Tendon of extensor carpi radialis brevis muscle Tendon of extensor carpi radialis longus muscle

I

Tendon of extensor pollicis brevis muscle Tendon of abductor pollicis longus muscle

Ulna

Radius Tendon of extensor indicis muscle

Lister’s tubercle

FIG. 9.128  Axial view of carpal tunnel and flexor tendons. Top, Flexor tendons. Bottom, Extensor tendons and compartments.

CHAPTER 9  Upper Extremity

Cruciate ligaments Deep transverse metacarpal ligament (DTML)

Annular ligaments

Flexor tendons

Extensor tendons Extensor retinaculum

Flexor retinaculum

FIG. 9.129  Left, Palmar view of flexor tendons. Right, Dorsal view of extensor tendons.

Extensor digitorum Flexor digitorum Cephalic and indicis tendons profundus tendons vein Extensor Second Fourth retinaculum Third metacarpal metacarpal Extensor digiti metacarpal (base) (base) (base) Dorsal minimi tendon P interosseous muscle Extensor carpi ulnaris tendon

Extensor pollicis longus tendon Extensor pollicis brevis tendon

Fifth metacarpal (base)

Radial artery and vein

Palmar interosseous muscle Opponens digiti minimi muscle

First metacarpal (base)

Flexor digitorum superficialis tendons

Adductor pollicis brevis muscle

Abductor digiti minimi muscle

Ulnar nerve

Ulnar artery

A

Median nerve

Flexor retinaculum

Abductor brevis pollicis muscle Flexor pollicis longus tendon

FIG. 9.130  Axial, T1-weighted MRI of wrist.

Opponens pollicis muscle

637

CHAPTER 9  Upper Extremity

638

Flexor digitorum profundus tendons Extensor carpi Extensor digitorum radialis brevis tendon tendons P

Extensor indicis tendon

Extensor retinaculum Extensor carpi radialis longus tendon

Basilic vein

Extensor pollicis longus tendon

Extensor digiti minimi tendon Extensor carpi ulnaris tendon

Capitate

Hamate

Cephalic vein

Trapezoid

Flexor digitorum superficialis tendons

Extensor pollicis brevis tendon

Trapezium

Abductor pollicis longus tendon

Abductor digiti minimi muscle

Flexor pollicis longus tendon

Ulnar nerve

Median nerve Hook of hamate

A Flexor retinaculum

Ulnar artery and vein

Palmaris longus tendon

FIG. 9.131  Axial, T1-weighted MRI of wrist with flexor retinaculum.

Extensor retinaculum

Extensor carpi brevis tendon Extensor digitorum Extensor tendons Extensor pollicis indicis tendon longus tendon Capitate Hamate P Extensor carpi radialis longus tendon

Extensor digiti minimi tendon

Scaphoid Extensor carpi ulnaris tendon

Radial artery and vein Abductor pollicis longus tendon

Triquetral Ulnar artery and vein

Radioscaphocapitate ligament Flexor digitorum profundus tendons

Pisiform Ulnar nerve

Flexor carpi radialis tendon Median nerve Flexor carpi ulnaris tendon

Guyon canal

A Flexor digitorum superficialis tendons

Palmaris longus Flexor tendon retinaculum

FIG. 9.132  Axial, T1-weighted MRI of wrist with Guyon canal.

CHAPTER 9  Upper Extremity Extensor pollicis longus tendon Extensor digiti Extensor digitorum minimi tendon tendons P

Extensor retinaculum

Extensor carpi brevis radialis tendon

Lister’s tubercle Extensor carpi radialis longus tendon

Extensor indicis tendon

Extensor pollicis brevis tendon

Extensor carpi ulnaris tendon

Abductor pollicis longus tendon

Flexor digitorum profundus tendons

Radius

Ulna

Radial nerve Pronator quadratus muscle

Ulnar nerve

Flexor pollicis longus tendon

Ulnar artery and vein

Flexor carpi radialis tendon Median nerve Flexor carpi ulnaris muscle and tendon

A

Flexor digitorum superficialis tendons

Palmaris longus tendon

FIG. 9.133  Axial, T1-weighted MRI of wrist with compartments of extensor tendons.

Lunate

Scapholunate ligament P

Dorsal radiocarpal ligament

Lunotriquetral ligament Scaphoid Triquetral Flexor digitorum profundus tendons

Flexor carpi radialis tendon

Median nerve

A Flexor digitorum superficialis tendons

FIG. 9.134  Axial, T1-weighted MRI of wrist, post-arthrogram.

639

CHAPTER 9  Upper Extremity

640

Hamate

P

Capitate

Extensor pollicis longus tendon

Extensor carpi radialis longus tendon

Extensor carpi ulnaris tendon Triquetral

Scaphoid Pisiform Flexor carpi radialis tendon Median nerve A

FIG. 9.135  Axial, T1-weighted MRI of proximal wrist, post-arthrogram.

S

S

Capitate Trapezoid

Capitate

Hamate

Lunate

Trapezium

A

Midcarpal joint

P

Scaphoid

R

Flexor tendons

L Joint capsule

Triquetrum Triangular fibrocartilage complex Distal radioulnar joint

Ulna

Joint capsule

Radiocarpal compartment

Radius

Radius

Pronator quadratus muscle

I Lunate

FIG. 9.136  Coronal, T1-weighted MRI of wrist, post-arthrogram.

I

FIG. 9.137  Sagittal, T1-weighted MRI of wrist, postarthrogram.

CHAPTER 9  Upper Extremity

Ligaments of the Fingers.  The MCP and interpha-

langeal joints each have a palmar plate (ligament) and two collateral ligaments. The palmar plate (ligament) is a thick, dense fibrocartilaginous tissue that covers the palmar surface of the joints. The palmar plate runs between and is connected to the collateral ligaments, creating the floor of the interphalangeal and MCP joints (Fig. 9.138). The deep transverse metacarpal ligament (DTML) consists of a series of short ligaments that connect the palmar plate of the metacarpal heads

Proximal interphalangeal joint

Distal interphalangeal joint

Proximal phalanx Middle phalanx

Metacarpophalangeal joint

Distal phalanx

Collateral ligament (cordlike part)

641

(Fig. 9.129). The DTML prevents separation of the metacarpals. Along the palmar surface of the fingers, the ligamentous structures of the radial and ulnar col­ lateral ligaments, radial and ulnar accessory collateral ligaments, and palmar plates provide stability for the MCP and interphalangeal joints (Fig. 9.138). There is a fibro-osseous tunnel along the palmar aspect of each finger for the passage of the flexor tendons. The tunnel is created by well-defined areas of thickening of the tendon sheath and is called the annular pulley system. It is composed of five annular pulleys and three cruciate pulleys, which are important structures that prevent the displacement of the tendons during flexion of the fingers (Fig. 9.139). The dorsal surface of the hand and fingers contains the extensor mechanism or extensor hood. The extensor hood consists of the digital extensor tendon, extensor hood proper, and insertions of the lumbricals and interossei muscles and serves to maintain the integrity of the extensor tendons along the path of the MCP and interphalangeal joints (Figs. 9.140–9.144).

Palmar plate (ligament)

The flexor tendon pulley system of the fingers is responsible for one of the most common injuries in experienced climbers. It involves partial or complete rupture of one or more flexor tendon annular pulleys. The A2 pulley ruptures more frequently than the A4 pulley due to the common crimp grip, which places much higher force on the pulley system. Common symptoms of a pulley rupture are a loud, audible pop accompanied by pain, bowstringing of the tendon, localized swelling or tenderness, and limited mobility of the joint.

Collateral ligament (fanlike part) Metacarpal

A4 pulley A3 pulley Proximal phalanx Collateral ligament of proximal interphalangeal joint

C1 pulley

Accessory collateral ligament

Palmar plate (ligament)

A5

A5 C3

C3

A4

A4

C2

C2

A3 C1

A3 C1

A2

A2

A1

A1

A2 pulley

Five annular pulleys Three cruciate pulleys

Metacarpal

FIG. 9.139  Annular pulley system. Left, Lateral view. Right, Palmar view.

FIG. 9.138  Palmar plate. Top, Lateral view. Bottom, Palmar view.

642

CHAPTER 9  Upper Extremity Insertion of extensor tendon to base of distal phalanx

Distal phalanx Distal interphalangeal joint

Middle phalanx Oblique retinacular ligament

Triangular ligament Proximal interphalangeal joint

Central slip of extensor tendon

Proximal phalanx

Metacarpophalangeal joint Extensor hood Palmar interosseous muscle

A

Lumbrical muscle Extensor tendon

Dorsal interosseous muscle

Metacarpal

Dorsal Metacarpointerosseous phalangeal joint muscle Extensor tendon

B

Proximal interphalangeal joint Distal interphalangeal joint

Extensor hood

Lumbrical muscle Palmar Deep transverse interosseous metacarpal muscle ligament Dorsal and palmar interosseous muscles

Transverse retinacular ligament

Oblique retinacular ligament

Collateral ligament

Extensor hood

Lumbrical muscle

Deep transverse metacarpal ligament

C

Transverse retinacular ligament

Oblique retinacular ligament

FIG. 9.140  Extensor mechanism of finger. (A) Dorsal view. (B) Lateral view. (C) Lateral view in flexion.

CHAPTER 9  Upper Extremity

643

Extensor tendon

Proximal articular surface of the proximal phalanx

Extensor hood Main collateral ligament Accessory collateral ligament

Interosseous tendon

Deep transverse metacarpal ligament

Lumbrical muscle and tendon Palmar plate (ligament)

A1 pulley Flexor tendons

FIG. 9.141  Axial view of metacarpophalangeal joint structures. Ulnar collateral ligament

P

Extensor digitorum

Radial collateral ligament Dorsal digital vein

Interosseous muscles and tendons Deep transverse metacarpal ligament Palmar digital nerve and artery

4th

5th MC

3rd

MC

MC

Interosseous muscles and tendons

2nd

MC

Palmar plate (ligament)

Lumbrical muscle

Deep transverse metacarpal ligament

Annular pulleys

A

Palmar digital nerve and artery Flexor digitorum Lumbrical superficialis and muscle profundus tendons

FIG. 9.142  Axial, T1-weighted MRI of left hand with metacarpals. P Extensor tendon (central band)

Dorsal (extensor) expansion

Proximal interphalangeal joint

Proximal phalanx Extensor digitorum tendon

Middle phalanx Extensor tendon (common band)

Metacarpophalangeal joint Metacarpal head

Distal interphalangeal joint

Flexor digitorum profundus tendon

Distal phalanx Palmar plate (ligament) Flexor digitorum profundus tendon

Flexor digitorum profundus tendon Flexor digitorum superficialis tendon

Annular pulley

Flexor digitorum superficialis tendon

Palmar plate (ligament) A

FIG. 9.143  Sagittal, T1-weighted MRI of finger.

CHAPTER 9  Upper Extremity

644

Muscles and Tendons The numerous muscles of the forearm become tendinous just before the wrist joint. The many tendons located in the wrist can be divided into flexor (palmar) and extensor (dor­ sal) tendon groups (Figs. 9.129, 9.133, 9.145, and 9.146). Collateral ligaments

The flexor tendon group collectively flexes the fingers and wrist. As this group courses through the carpal tunnel, the tendons appear to be arranged in two discrete rows (Figs. 9.128, top, and 9.131). The tendons of the extensor group span the superficial surface of the wrist to extend the fingers and wrist (Figs. 9.128–9.135 and 9.137).

S Metacarpophalangeal joint Base of proximal phalanx Head of metacarpal

R

L

Interosseous muscles Base of metacarpal

FIG. 9.144  Coronal, T1-weighted MRI of finger.

I

S

Third metacarpal (base) Capitate Dorsal intercarpal ligament

Flexor tendons

Extensor tendons A

P Lunate

Radiolunate ligament

Radius

Pronator quadratus muscle

I

FIG. 9.145  Sagittal, T1-weighted MRI of wrist with flexor and extensor tendons.

CHAPTER 9  Upper Extremity

645

S

Hypothenar muscle group

Thenar muscle group

Flexor tendons

Radius Ulnar artery

I

FIG. 9.146  3D CT of wrist with flexor tendons.

Muscles of the Hand.  The muscles of the hand can

be divided into three groups: (1) metacarpal group (muscles of the metacarpals are considered to be the central muscles of the hand), (2) thenar group (muscles involving the thumb and creating the thenar eminence on the radial side), and (3) hypothenar group (muscles involving the fifth digit and creating the hypothenar eminence on the ulnar side). These muscles are shown in Figs. 9.147–9.154.

Metacarpal Group  Interossei Lumbricals

The metacarpal muscle group includes the interossei and lumbrical muscles. There are seven short interossei muscles in the metacarpal muscle group: three single-headed muscles located on the palmar surface and four double-headed muscles located on the dorsal surface (Figs. 9.140 and 9.147A and B). The three palmar interossei muscles arise from the second, fourth, and fifth metacarpals and insert on the corresponding proximal phalanges, frequently radiating into the corresponding tendons of the dorsal aponeurosis. These muscles are responsible for flexion at the MCP joints and extension at the interphalangeal joints. The dorsal interossei arise from two heads on the

sides of the five metacarpal bones to insert on the proximal phalanges and radiate onto the dorsal aponeurosis. Like their palmar counterparts, the dorsal interossei flex at the MCP joints and extend at the interphalangeal joints. The four small lumbrical muscles arise from the tendons of the flexor digitorum profundus and pass to the radial side of the corresponding finger to insert on the extensor expansion covering the dorsal surface of the finger (Figs. 9.140; 9.147, right; and 9.148). The lumbricals flex the first phalanges at the MCP joints and extend the second and third phalanges at the interphalangeal joints.

Thenar Group 

Abductor pollicis brevis Flexor pollicis brevis Adductor pollicis Opponens pollicis The abductor pollicis brevis is a thin, flat superficial muscle arising from the transverse carpal ligament, navicular, and trapezium (Figs. 9.148 and 9.149). It runs inferiorly and laterally to insert on the base of the first phalanx of the thumb to abduct the thumb. The flexor pollicis brevis has two heads: The superficial or lateral head arises from the flexor retinaculum,

646

CHAPTER 9  Upper Extremity

and the deep or medial head arises from the trapezium, trapezoid, and capitate. This muscle inserts on the radial and ulnar base of the first phalanx to flex, adduct, and abduct the thumb (Figs. 9.148 and 9.149). Frequently, a sesamoid bone can be found in the insertion tendon on the radial side. The adductor pollicis also has two heads: The transverse head arises from the dorsal aspect of the third metacarpal, and the oblique head arises from numerous slips off the capitate, the bases of the second and third metacarpals, and the sheath of the flexor carpi radialis tendon. The adductor pollicis inserts onto the base of the first phalanx of the thumb to provide adduction and assist in the opposition and flexion of the thumb (Figs. 9.148 and 9.149). The opponens pollicis provides the main opposition for the thumb but also assists with adduction. It arises from the trapezium and flexor retinaculum and inserts onto the radial aspect of the first metacarpal (Figs. 9.148 and 9.149).

Axial line

2

Hypothenar Group 

Abductor digiti minimi Flexor digit minimi brevis Opponens digiti minimi The abductor digiti minimi muscle arises from the pisiform and the flexor retinaculum to end in a flat tendon that inserts onto the ulnar base of the first phalanx of the little finger (Figs. 9.148 and 9.149). The abductor digiti minimi muscle is the main abductor of the little finger. The flexor digiti minimi brevis muscle arises from the flexor retinaculum and the hook of the hamate. It fuses with the tendon of the abductor digiti minimi to insert on the base of the first phalanx of the fifth digit (Figs. 9.148 and 9.149). The flexor digiti minimi brevis flexes at the MCP joint. Like the flexor digiti minimi brevis muscle, the op­ ponens digiti minimi arises from the hook of the hamate and the flexor retinaculum (Fig. 9.148). It inserts on the ulnar surface of the fifth metacarpal to bring the little finger into the position for opposition.

Axial line

3

1

2

3 1

3

4

Palmar interossei (1–3)

Dorsal interossei (1–4)

2

4

1

Lumbricals (1–4)

FIG. 9.147  Left, Palmar view of interosseous muscles. Center, Dorsal view of interosseous muscles. Right, Lumbrical muscles.

CHAPTER 9  Upper Extremity

647

Fibrous sheath Tendons of: Flexor digitorum profundus Flexor digitorum superficialis

Third lumbrical

Second lumbrical Dorsal interossei First lumbrical Dorsal interossei

Fourth lumbrical Opponens digiti minimi Flexor digiti minimi brevis Abductor digiti minimi Pisiform bone Flexor carpi ulnaris tendon Flexor digitorum superficialis tendons

Adductor pollicis Flexor pollicis brevis Abductor pollicis brevis Opponens pollicis Flexor retinaculum Abductor pollicis longus Tendons of: Palmaris longus Flexor pollicis longus Flexor carpi radialis

FIG. 9.148  Palmar view of flexor pollicis brevis, flexor digiti minimi, abductor pollicis brevis, opponens pollicis, and abductor digiti minimi muscles.

Flexor digitorum profundus tendon Flexor digitorum superficialis tendon Dorsal interossei

Palmar interossei Opponens digiti minimi Flexor pollicis brevis Flexor digiti minimi brevis (cut) Abductor digiti minimi (cut)

Flexor pollicis longus tendon Abductor pollicis brevis Adductor pollicis Opponens pollicis

FIG. 9.149  Palmar view of adductor pollicis and opponens digiti minimi muscles.

648

CHAPTER 9  Upper Extremity Dorsal interosseous muscles

P

3

4

2 Adductor pollicis muscle

5

1

Abductor digiti minimi muscle

A

Opponens digiti minimi muscle

Palmar interosseous muscles

Flexor pollicis brevis muscle

FIG. 9.150  Axial, T1-weighted MRI of hand.

Dorsal interosseous muscles

P Dorsal interosseous muscles Adductor pollicis muscle

2

3 4

1 Flexor pollicis longus tendon

5

Opponens pollicis muscle Adductor minimi muscle

Palmar interosseous muscles

A

FIG. 9.151  Axial, T1-weighted MRI of hand with dorsal interosseous muscles.

CHAPTER 9  Upper Extremity

649

S Lumbrical muscles

Abductor pollicis brevis muscle Flexor digiti minimi muscle Abductor digiti minimi muscle Flexor digitorum tendons Hook of hamate Pisiform Trapezium Ulna I

FIG. 9.152  Coronal, T1-weighted MRI of wrist and hand.

S

S First metacarpal

Dorsal interosseous muscles

Palmar interosseous muscles

Opponens pollicis muscle Adductor pollicis muscle Opponens pollicis muscle

Trapezoid

Trapezium

Capitate

Trapezoid

Hamate

Hamate Capitate

Scaphoid

Triquetrum Lunate Scaphoid

Radius

Ulna Radius I

FIG. 9.153  Coronal, T1-weighted MRI of wrist and hand with palmar interosseous muscles.

I

FIG. 9.154  Coronal, T1-weighted MRI of wrist and hand with opponens pollicis muscle.

650

CHAPTER 9  Upper Extremity

Costocervical trunk

Inferior thyroid artery

Vertebral artery

S

Left and right common carotid arteries

Thyrocervical trunk Transverse cervical artery Suprascapular artery Left subclavian artery Acromial branch of thoracoacromial artery

Right subclavian artery First rib Arch of aorta

Axillary artery Thoracoacromial artery

Manubrium of sternum

Posterior and anterior humeral circumflex arteries

Pectoral branch of thoracoacromial artery

Subscapular artery

Internal thoracic artery

Brachial artery

Superior thoracic artery Dorsal scapular artery Lateral thoracic artery

Profunda brachii artery

Superior ulnar collateral artery Inferior ulnar collateral artery L R Anterior and posterior ulnar recurrent arteries

Radial recurrent artery

Common interosseous artery

Posterior interosseous artery passing deep to interosseous membrane

Ulnar artery Anterior interosseous artery Radial artery

A

Superficial palmar branch of ulnar artery Deep palmar arch Superficial palmar arch

I

FIG. 9.155  (A) Anterior view of arteries of the upper extremity.

CHAPTER 9  Upper Extremity S

Basal metacarpal branch Capitate

Radial artery

Hamate

Trapezium

Medial branch of ulnar artery

Trapezoid Dorsal intercarpal arch

Artery to dorsal ridge of scaphoid Dorsal intercarpal arch

Lunate

Trapezoid

Dorsal radiocarpal arch Radius

P

Lunate

Scaphoid Dorsal radiocarpal arch

Ulnar artery Ulna

Radial artery

Dorsal branch of posterior interosseous artery

I

Radius

Second metacarpal Trapezium

Branch to dorsal ridge of scaphoid

Triquetrum

B

651

Superficial palmar arch First metacarpal

A

Radial artery

Branch to lateral trapezium and first metacarpal

Palmar radiocarpal arch Superficial palmar artery Scaphoid

Branch to scaphoid tubercle and trapezium

FIG. 9.155, cont’d   (B) Posterior view of arteries of wrist. (C) Lateral view of arteries of wrist.

NEUROVASCULATURE The neurovasculature of the upper extremity is composed primarily of the branches of the axillary and brachial arteries, their accompanying deep veins, a system of superficial veins, and the brachial plexus that innervates the upper extremity.

Arterial Supply Shoulder.  The primary arteries supplying the shoul-

der region include the axillary and brachial arteries (Fig. 9.155). The axillary artery begins at the lateral border of the first rib as a continuation of the subclavian artery. It ends at the inferior border of the teres major muscle, where it passes into the arm and becomes the brachial artery. The axillary artery and its branches supply blood to numerous thoracic and shoulder structures, including the first and second intercostal spaces; the axillary lymph nodes; the mammary gland in women; and the scapular, serratus anterior, pectoral, latissimus dorsi, deltoid, and triceps brachii muscles. The branches of the axillary artery typically include the superior thoracic, thoracoacromial, lateral thoracic, subscapular, and anterior and posterior humeral circumflex arteries. The bra­ chial artery is the principal arterial supply to the arm. It courses inferiorly on the medial side of the humerus and then continues anterior to the cubital fossa of the elbow. The brachial artery is relatively superficial and palpable throughout its course. It accompanies the median nerve, which crosses anterior to the artery in the middle of the arm. During its course, the brachial artery gives rise to numerous muscular branches, which include the profunda brachii, superior ulnar collateral, and inferior ulnar collateral arteries (Figs. 9.155A–9.160).

Elbow.  The brachial artery divides at the cubital fossa into the radial and ulnar arteries (Fig. 9.155A). The radial artery begins at the level of the head of the radius within the anterior compartment of the forearm. It courses beneath the brachioradialis muscle and then continues its course just deep to the skin, along the lateral side of the anterior forearm to the wrist. It passes anterior to the radial styloid process to enter the hand. The most proximal branch of the radial artery is the radial recur­ rent artery, which supplies the brachioradialis, supinator, and brachialis muscles and the elbow joint. Within the forearm, the radial artery gives off several direct muscular branches. The ulnar artery also gives rise to several branches that supply the elbow and forearm. The first branch of the ulnar artery is the anterior ulnar recurrent artery, which supplies the brachialis and pronator teres muscles. It courses just anterior to the medial condyle of the humerus to anastomose with the inferior ulnar collateral branch of the brachial artery. The posterior ulnar recurrent artery courses behind the medial epicondyle of the humerus to anastomose with the superior ulnar collateral branch of the brachial artery. It supplies the flexor carpi ulnaris, pronator teres, and anconeus muscles. The common interosseous artery branches from the ulnar artery and almost immediately bifurcates into the anterior and posterior interosseous arteries. These arteries and their branches supply the median nerve, deep flexor and extensor muscles of the forearm, superficial extensor muscles of the forearm, and radius and ulna (Figs. 9.155, 9.156B and C, 9.157, 9.159, and 9.160). Wrist and Hand.  The terminal branches of the radial

and ulnar arteries form the palmar arches of the wrist and hand. These arches emit branches that serve the wrist,

C

CHAPTER 9  Upper Extremity

652

Brachial artery

S

Profunda brachii artery

R

L Axillary artery Clavicle

Humerus

First rib

Subscapular artery

A Scapula

I

Lateral thoracic artery S

S Radius

Anterior interosseous artery

Posterior interosseous artery

Radial artery

Posterior ulnar recurrent artery

Ulnar artery

Palmar carpal arch

Anterior ulnar recurrent artery Ulnar artery

Ulna

Ulna Brachial artery

Humerus

B I

Radial artery

C Anterior interosseous artery

I

Radius

FIG. 9.156  (A) 3D CT of axillary artery. (B) 3D CT of brachial artery. (C) 3D CT of radial and ulnar arteries.

CHAPTER 9  Upper Extremity Palmar metacarpal artery

Common palmar digital artery

Proper palmar digital artery

S

I Radial artery

Deep palmar arch

Ulnar artery

FIG. 9.157  MRA of hand.

653

CHAPTER 9  Upper Extremity

654

Axillary artery

Pectoralis major muscle

A

Pectoralis minor muscle Internal thoracic artery

Deltoid muscle

Subscapular artery

Humerus L

R Axillary vein Subclavian vein

Subscapularis muscle

Infraspinatus muscle

P

FIG. 9.158  Axial CT of right shoulder with axillary artery.

Ulnar vein

A

Ulnar artery

Flexor digitorum superficialis muscle

Flexor carpi radialis muscle

Ulna L

R

Radial artery and vein

Brachioradialis muscle

Extensor carpi radialis longus muscle

Radius

P

Anterior interosseous artery and vein

FIG. 9.159  Axial CT of right forearm with radial and ulnar arteries.

CHAPTER 9  Upper Extremity Median nerve

A

Ulnar artery and vein

655

Ulnar nerve

Radial artery and vein Palmar carpal arch

Cephalic vein

Ulna

Radius

P

FIG. 9.160  Axial CT of right wrist with radial and ulnar arteries. palm, and digits (Figs. 9.155, 9.156C, and 9.157). The palmar radiocarpal arch or network is formed by the palmar carpal branches from the radial and ulnar arteries; the anterior interosseous artery, also a branch of the ulnar artery; and a recurrent branch from the deep palmar arch. These vessels supply the carpal bones and joints (Fig. 9.155A and C). The dorsal radiocarpal arch or network is formed by dorsal carpal branches of the radial and ulnar arteries. The dorsal carpal arch also receives contributions from the anterior and posterior interosseous arteries. The arch lies close to the dorsal surface of the carpals and gives rise to three dorsal metacarpal arteries and branches that supply the distal regions of the ulna and radius, carpal bones, and intercarpal joints (Fig. 9.155). The superficial palmar branch of the radial artery anastomoses with the superficial palmar branch of the ulnar artery to form the superficial palmar arch. This arch gives rise to three common palmar digital arteries that anastomose with the palmar metacarpal arteries from the deep palmar arch (Fig. 9.155A and C). The deep palmar arch is formed by deep palmar branches of the radial and ulnar arteries and is located approximately 1 cm proximal to the superficial palmar arch. The deep palmar arch also gives rise to a recurrent branch that anastomoses with the palmar carpal branches of the radial and ulnar arteries (Fig. 9.155A).

Venous Drainage The veins of the upper extremity are divided into deep and superficial groups (Fig. 9.161). Numerous anastomoses occur between the groups. The superficial venous system consists of extensive venous networks that are especially well developed within the upper extremity along with their accompanying arteries of the same

name. The deep veins are often double and repeatedly anastomose with one another.

Shoulder.  The veins of the upper arm include the bra-

chial, cephalic, and basilic (Fig. 9.161). The two deep brachial veins ascend the arm, one on either side of the brachial artery. The brachial veins begin in the elbow from the union of the ulnar and radial veins and end in the axillary vein near the lower margin of the subscapularis muscle. The two deep brachial veins may join to form one brachial vein during part of their course. The superficial veins of the upper arm include the cephalic and basilic. The cephalic vein courses from the radial side of the dorsal venous arch of the hand and then ascends to the midpoint of the forearm, where it curves around to the ventral surface of the forearm and ascends the lateral aspect of the upper arm, along the anterolateral border of the biceps brachii muscle, to open into the axillary vein, just below the clavicle. It drains the superficial parts of the lateral hand and lateral forearm. The basilic vein originates from the medial end of the dorsal venous arch of the hand. It then ascends the ulnar side of the forearm, along the medial surface of the biceps brachii muscle in the upper arm, to form the axillary vein. The basilic vein drains the superficial parts of the medial side of the hand and medial side of the forearm. The large axillary vein lies on the medial side of the axillary artery. It extends from the lower border of the teres major muscle to the lateral surface of the first rib to continue as the subclavian vein. The axillary vein receives tributaries that correspond to the branches of the axillary artery (Figs. 9.158 and 9.161).

Elbow.  The large deep vein of the elbow is the brachial vein, which is formed by the union of the radial and ulnar

656

CHAPTER 9  Upper Extremity S

Internal jugular vein

Subclavian vein

Brachiocephalic vein Axillary vein

Cephalic vein

Brachial veins

Basilic vein

Median cubital (basilic) vein Ulnar vein Intermediate antebrachial vein Radial vein

To basilic vein

To cephalic vein Dorsal venous network

Digital veins

B

A

I

FIG. 9.161  (A) Anterior view of upper extremity veins. (B) Posterior view of the superficial veins of the hand. veins (Fig. 9.159). The superficial veins of the elbow include the cephalic, median cubital, basilic, and intermediate (median) antebrachial veins. The cephalic vein courses along the radial side of the elbow and may give rise to the median cubital vein, which ascends in an oblique and medial course to create an anastomosis between the basilic and cephalic veins (Fig. 9.161). The median cubital vein is a common site for venipuncture. The basilic vein courses along the posteromedial aspect of the forearm, crosses the elbow, then takes a deep course in the axilla to join the brachial vein. The intermediate (median) antebrachial vein transports blood from the superficial palmar venous arch and anterior forearm. It ascends the ventral side of the forearm on the ulnar side and typically ends in the basilic vein (Figs. 9.94–9.102).

Wrist and Hand.  The superficial venous system forms

a network at the dorsum of the hand termed the dorsal venous network (arch). It is fed by the subcutaneous

dorsal metacarpal veins of the fingers and continues to the distal forearm, where it drains into three major superficial veins: the cephalic, basilic, and intermediate (median) antebrachial veins of the forearm (Figs. 9.128 and 9.130–9.133). These large superficial veins anastomose frequently as they course superiorly. The deep and superficial palmar venous arches of the hand empty into the radial and ulnar veins that then unite to form the brachial vein of the arm (Fig. 9.161).

Innervation The brachial plexus, also described in Chapter 4, is a large network of nerves that innervate the upper limb (Figs. 9.22, 9.23, 9.47, and 9.162). It extends from the neck into the axilla. The brachial plexus is formed by the union of the ventral rami of nerves C5–C8 and the greater part of the T1 ventral ramus. The ventral rami from C5 and C6 unite to form a superior trunk, the

CHAPTER 9  Upper Extremity S

Humerus Radial nerve Musculocutaneous nerve Lateral cutaneous nerve Radial nerve (superficial branch) Radius

Median nerve Ulnar nerve Ulna

Dorsal branch of ulnar nerve

Muscular branch

A

Superficial branch of ulnar nerve

Median nerve

Digital branch of ulnar nerve

Digital branch I

Dorsal scapular Nerve to subclavius

Roots: S C4 C5 C6

Suprascapular

C7

Posterior divisions

C8

Lateral Roots Posterior

Middle Trunks Lower

T1

Median

Long thoracic

Axillary

B

Upper

Medial pectoral

Musculocutaneous

Lateral pectoral Upper subscapular

Radial

Lower subscapular

Median

Thoracodorsal

I Ulnar

Key: Roots

Medial cutaneous nerves of the arm and forearm Trunks

Anterior division Posterior division

FIG. 9.162  (A) Anterior view of the upper extremity nerves. (B) Anterior view of the brachial plexus.

657

658

CHAPTER 9  Upper Extremity

ventral ramus of C7 continues as the middle trunk, and the ventral rami of C8 and T1 unite to form an inferior trunk. Each of these trunks divides into an anterior and posterior division. The anterior divisions supply the anterior (flexor) parts of the upper limb, and the posterior divisions supply the posterior (extensor) parts of the upper limb. These divisions form three cords (posterior, lateral, and medial), which continue to divide to form the median, ulnar, musculocutaneous, and radial nerves (sequential Figs. 9.62–9.67). These nerves supply the muscles of the forearm and hand. The median nerve descends the cubital fossa deep to the median cubital vein. It supplies the pronator teres muscle of the arm and all the superficial and deep flexor muscles of the forearm, except the flexor carpi ulnaris muscle. It gives off an anterior interosseous branch that descends within the forearm to supply the flexor digitorum profundus muscle. The median nerve courses through the carpal tunnel of the wrist, typically superficial to the flexor tendons (Fig. 9.163). It supplies the flexors of the hand, the skin of the wrist, the thenar eminence, the palm of the hand, and the sides of the first three digits and the lateral half of the fourth. At the elbow, the ulnar nerve passes between the medial epicondyle of the humerus and the olecranon process within the cubital tunnel to enter the medial side of the flexor compartment of the forearm (Figs. 9.87 and 9.162). Posterior to the medial epicondyle, the ulnar nerve is superficial and easily palpable. It supplies the flexor carpi ulnaris muscle and the medial side of the flexor digitorum profundus muscle in the forearm before entering the hand. The ulnar nerve passes under the flexor retinaculum, along with the ulnar artery, to enter the palmar compartment of the hand (Fig. 9.163). At this point, the ulnar nerve divides into superficial and deep terminal branches that supply the ulnar flexors of the hand, as well as the skin on the medial side of the palm, medial half of the dorsum of the hand, fifth digit, and medial half of the fourth digit. The musculocutaneous nerve descends to the lateral side of the arm and elbow to innervate the flexors in the arm and the skin of the forearm, wrist, and thenar region of the hand (Fig. 9.162). It emits branches that supply both heads of the biceps brachii muscle, the brachialis muscle, and the elbow joint. It innervates the skin of the dorsal surface of the arm. A continuation of the musculocutaneous nerve is the lat­ eral cutaneous nerve, which terminates into cutaneous branches that supply the skin covering the radial side of the wrist and the thenar eminence. The radial nerve is the largest branch of the brachial plexus. It passes inferolaterally around the body of the humerus in the radial groove (Fig. 9.162). It continues inferiorly between the brachialis and brachioradialis muscles to the level of the lateral epicondyle of the humerus, where it divides into deep and superficial branches. The deep branches supply all the extensors in the arm and forearm, and the cutaneous branches innervate the skin on the dorsal side of the arm and hand. The superficial branch, the direct continuation

S

Superficial palmar arch

Deep palmar arch

Flexor retinaculum Flexor tendons Ulnar nerve

Median nerve

Ulnar artery Radial artery I

FIG. 9.163  Palmar view of neurovasculature of hand and wrist. of the radial nerve, is entirely sensory. It supplies the skin and fascia over the lateral two-thirds of the dorsum of the hand, the dorsum of the thumb, and the proximal parts of the lateral three and a half digits on their dorsal surfaces (Figs. 9.93–9.102).

REFERENCES Anderson, M. W., & Fox, M. G. (2017). Sectional anatomy by MRI and CT (4th ed.). Philadelphia: Elsevier. Frank, G. (2012). Merrill’s atlas of radiographic positions and radiologic procedures (12th ed.). St. Louis: Mosby. Haaga, J. R., & Boll, D. T. (2017). CT and MRI of the whole body (6th ed.). Philadelphia: Elsevier. Manaster, B. J. (2016). Diagnostic imaging: musculoskeletal: Nontraumatic disease (2nd ed.). Philadelphia: Elsevier. Manaster, B. J., & Crim, J. (2016). Imaging anatomy: Musculoskeletal (2nd ed.). Philadelphia: Elsevier. Miller, M. D., & Cooper, D. E. (2002). Review of sports medicine and arthroscopy (2nd ed.). Philadelphia: Elsevier. Palastanga, N. (2002). Anatomy and human movement: Structure and function (4th ed.). Boston: Butterworth-Heinemann. Seidel, H. M., Ball, J. W., Dains, J. E., et al. (2010). Mosby’s guide to physical examination (7th ed.). St. Louis: Mosby. Standring, S. (2012). Gray’s anatomy, the anatomical basis of clinical practice (41st ed.). New York: Elsevier. Weir, J., & Abrahams, P. H. (2011). Imaging atlas of human anatomy (4th ed.). London: Elsevier.

CHAPTER

10

Lower Extremity And well observe Hippocrates’ old rule, the only medicine for the foote is rest. Thomas Nash (1567–1601), Summer’s Last Will and Testament

The complex anatomy of the lower extremity is responsible for bearing the entire upper body weight and for accommodating the demands of movement placed on this system (Fig. 10.1).

FIG. 10.1  Multiple fractures of the distal tibia and fibula.

OBJECTIVES • Identify the bony anatomy of the lower extremity. • Identify and state the actions of the lower extremity muscles, as well as their origins and insertions. • Describe the labrum and articular capsule of the hip. • List and describe the ligaments, retinacula, and tendons of the lower extremity joints.

• Define and identify the meniscus and articular capsule of the knee. • Identify the bursae of the hip and knee. • List and identify the major arteries and veins of the lower extremity. • Describe the nerves that innervate the lower extremity.

OUTLINE HIP, 660 Bony Anatomy, 660 Labrum and Ligaments, 665 Joint Capsule, 672 Bursae, 672 Muscles of the Hip and Thigh, 672 KNEE AND LOWER LEG, 687 Bony Anatomy, 687

Knee Joint, 694 Tendons, 709 Bursae, 709 Muscles of the Lower Leg, 709 ANKLE AND FOOT, 719 Bony Anatomy, 719 Joints, 727 Arches, 727

Copyright © 2019, Elsevier Inc.

Retinacula, Fascia, and Ligaments, 734 Tendons, 747 Muscles of the Foot, 748 NEUROVASCULATURE, 752 Arteries, 752 Veins, 757 Nerves, 759

659

660

CHAPTER 10  Lower Extremity

HIP The hip provides strength to carry the weight of the body in an erect position. This synovial ball-and-socket joint, created by the articulation of the femoral head with the acetabulum of the pelvis, allows for a wide range of motion.

Bony Anatomy Acetabulum.  A cuplike cavity termed the acetabulum is created by the three bones of the pelvis: ilium, ischium,

and pubis (Fig. 10.2; see also Chapter 8, bony anatomy of the pelvis). In axial cross-section, this area can be divided into sections known as the anterior and posterior columns. The posterior column is stronger and contributes to the weight-bearing portion of the acetabulum (Fig. 10.3). Within the acetabulum is a centrally located, nonarticulating depression called the acetabular fossa. It is formed mainly by the ischium and is filled with fat (Fig. 10.4). A continuation of the acetabular fossa is the acetabular notch, which interrupts the smooth circumference of the acetabular rim inferiorly and functions as an attachment site for the transverse acetabular ligament (Fig. 10.2).

Ilium S

P

A Acetabulum Acetabular fossa

Ischium

Acetabular notch Pubis

FIG. 10.2  Lateral aspect of right hip.

I Anterior column

Acetabular fossa

Femoral head

A

Posterior column

P

Acetabulum

Fovea capitis

FIG. 10.3  Axial CT of left hip joint, post-arthrogram.

CHAPTER 10  Lower Extremity Rectus femoris muscle

Sartorius muscle

A

Iliopsoas muscle

661

Femoral artery

Tensor fasciae latae muscle

Femoral vein Anterior acetabular labrum

Gluteus medius muscle

Anterior column

Iliofemoral ligament

Ligamentum teres

Greater trochanter

Fat within acetabular fossa L

R IT band

Acetabulum

Femoral head

Obturator internus muscle Posterior column

Gluteus maximus muscle Obturator internus tendon

Sciatic nerve P

Superior gemellus muscle

FIG. 10.4  Axial, T1-weighted MRI of right hip.

Femur.  The femur is the longest, heaviest, and stron-

gest bone in the body. The proximal end of the femur consists of a head, a neck, and two large processes: the greater and lesser trochanters (Figs. 10.5–10.12). On the proximal portion of the femur is the smooth, rounded femoral head. The femoral head is covered entirely by articular cartilage, with the exception of a small centrally located pit termed the fovea capitis. The fovea capitis is an attachment site for the ligamentum teres (Figs. 10.3–10.6, 10.9, and 10.12). Connecting the head of the femur to the femoral shaft is the femoral neck. The neck extends obliquely from the head at an angle of approximately 120 degrees in an inferolateral direction to meet the shaft (Fig. 10.5). The result of this angle is increased freedom of movement within the hip joint. At the distal end of the neck are two large bony prominences termed trochanters (Figs. 10.5–10.11). The greater trochanter is situated at the junction of the neck with the shaft. The superior portion of the greater trochanter projects above the neck and curves slightly posteriorly and medially (Figs. 10.4, 10.7, 10.9, and 10.10). The greater trochanter provides attachment for numerous muscles of the gluteal region (see Table 10.1). The lesser trochanter is at the posteromedial portion of the proximal shaft and provides insertion for the tendon of the iliopsoas muscle (Figs. 10.6, 10.9, and 10.10). The prominent ridge extending posteriorly between the trochanters at the base of the neck is the intertrochanteric

crest (Figs. 10.9 and 10.11). It provides an attachment site for the ischiofemoral ligament and part of the quad­ ratus femoris tendon. Connecting the trochanters anteriorly is the less prominent ridge termed the intertrochanteric line, which provides attachment for the iliofemoral ligament and part of the vastus lateralis tendon (Figs. 10.9 and 10.10). On the posterior surface of the femoral shaft is a raised ridge termed the linea aspera. Its medial and lateral lips provide attachment sites for muscles of the posterior and medial compartments of the thigh (Fig. 10.9). The pectineal line runs from the medial lip of the linea aspera to the lesser trochanter of the femur (Figs. 10.9 and 10.11). It is the insertion site for the tendon of the pectineus muscle. The lateral lip is very rough and runs almost vertically upward to the base of the greater trochanter. The widened portion of the lateral lip, the gluteal tuberosity, is an attachment site for the gluteus maximus and adductor magnus muscles (Figs. 10.9 and 10.11). The linea aspera extends down to the popliteal surface of the femur.

Avascular necrosis (AVN) is a major concern following subcapital fractures of the femoral head. Disruption of the arterial supply to the femoral head is the most significant factor leading to AVN.

662

CHAPTER 10  Lower Extremity S Ilium Femoral head

Articular cartilage Acetabular labrum

Ligamentum teres

Greater trochanter

L R Transverse acetabular ligament

Femoral neck

Fovea capitis Synovial cavity Joint capsule Lesser trochanter

I

FIG. 10.5  Coronal view of right hip joint.

S

Anterior superior iliac spine Iliopsoas muscle

Ilium Gluteus medius muscle

Acetabulum R

L Ligamentum teres

Gluteus minimus muscle

Obturator internus muscle

Femoral head Obturator externus muscle

Femoral neck

Ischium

Iliotibial (IT) band

Lesser trochanter I

FIG. 10.6  Coronal, T1-weighted MRI of right hip.

CHAPTER 10  Lower Extremity

A

Pubis

Femoral neck

Femoral head

R

L

P

Ischium

Greater trochanter

FIG. 10.7  Axial CT of hips with greater trochanter.

Femur

A

R

L

P

Inferior ramus of pubis

Lesser trochanter

FIG. 10.8  Axial CT of hips with lesser trochanter.

663

CHAPTER 10  Lower Extremity

664

Intertrochanteric line Fovea capitis

Pubis

Greater trochanter Intertrochanteric crest

Greater trochanter Head Lesser trochanter

Obturator foramen Intertrochanteric crest

Ischium

Pectineal line

Lesser trochanter

Lateral lip of linea aspera

Linea aspera

Pectineal line

Linea aspera Anterior

Femoral neck Greater trochanter

Gluteal tuberosity

Medial lip of linea aspera

S

Gluteal tuberosity

Posterior

R Femoral shaft

L Popliteal surface Medial and lateral supracondylar lines Lateral epicondyle

Popliteal surface

Adductor tubercle

Lateral epicondyle

Adductor tubercle Medial epicondyle

Patellar surface

Lateral supracondylar line

Intercondylar line

Medial condyle Intercondylar fossa

Intercondylar fossa

Lateral condyle

I

FIG. 10.9  Right femur. Left, Anterior view. Right, Posterior view.

Sacroiliac joint

Lateral femoral condyle

FIG. 10.11  3D CT of right femur, posterior aspect.

Sacral foramina

Sacral promontory

L5

Iliac crest

S Iliac fossa Anterior superior iliac spine

Sacrum

Anterior inferior iliac spine Superior pubic ramus Coccyx

Femoral head L

R

Femoral neck Acetabulum Greater trochanter of femur Intertrochanteric line

Obturator foramen

Pubic symphysis

I

Inferior pubic ramus

Ischial tuberosity

FIG. 10.10  3D CT of pelvis and hips.

Lesser trochanter of femur

CHAPTER 10  Lower Extremity

Labrum and Ligaments The femoral head is held to the acetabulum by the acetabular labrum and several major ligaments. The acetabular labrum, transverse acetabular ligament, iliofemoral ligament, ischiofemoral ligament, pubofemoral ligament, and ligamentum teres are shown in Figs. 10.12–10.26.

Labrum.  The acetabular labrum creates a fibrocartilaginous rim attached to the margin of the acetabulum.

665

This labrum closely surrounds the femoral head, helping to hold it in place by deepening the acetabular fossa, which adds increased stability to the joint (Figs. 10.12 and 10.21–10.24).

Ligaments.  The inferior margin of the acetabulum is incomplete and is reinforced by the transverse acetabular ligament that spans the acetabular notch at the inferior edge of the acetabulum (Figs. 10.2, 10.12, 10.20, and 10.24). As the transverse acetabular ligament

Ilium

Articular surface Acetabular labrum Ligamentum teres

Acetabular fossa

Fovea capitis

Transverse acetabular ligament Pubis

Ischium

FIG. 10.12  Femoral acetabulum and labrum. S Anterior inferior iliac spine

S Iliofemoral ligament

Iliofemoral ligament

Greater trochanter of femur

Ischium

Ischiofemoral ligament

Superior pubic ramus

L

Greater trochanter of femur Zona orbicularis

L R

Ischial tuberosity

R

Obturator externus bursa

Ischial tuberosity

Intertrochanteric line Pubofemoral ligament Lesser trochanter I

FIG. 10.13  Anterior view of right hip joint capsule.

Intertrochanteric crest

Lesser trochanter I

FIG. 10.14  Posterior view of right hip joint capsule.

666

CHAPTER 10  Lower Extremity Sartorius Iliopsoas muscle muscle

A

Femoral head

Femoral artery

Femoral vein

Tensor fasciae latae muscle Rectus femoris muscle

Obturator artery and vein

Iliofemoral ligament Gluteus medius muscle R

Obturator internus muscle L Ischiofemoral ligament

Iliotibial band

Superior gemellus muscle Sciatic nerve

Greater trochanter

Gluteus maximus muscle

Obturator internus tendon P

FIG. 10.15  Axial, T1-weighted MRI of right hip with ligaments

Iliopsoas muscle

Femoral Femoral Femoral artery head A nerve

Femoral vein Transverse acetabular ligament

Tensor fasciae latae muscle Rectus femoris muscle

Superior pubic ramus

Iliofemoral ligament

Ligamentum teres

Gluteus medius muscle

Obturator internus muscle

Iliotibial band

Ischiofemoral ligament

R

L Ischium

Greater trochanter

Inferior gemellus muscle Sciatic nerve Gluteus maximus muscle P

FIG. 10.16  Axial, T1-weighted MRI of right hip with ligaments and muscles.

CHAPTER 10  Lower Extremity

667

S Superior acetabular labrum Gluteus minimus muscle

Gluteus medius muscle

Gluteus maximus muscle

Ischiofemoral ligament L

R

Femoral neck

Iliofemoral ligament

Greater trochanter

Zona orbicularis

Transverse acetabular ligament

Lesser trochanter I

Acetabulum

FIG. 10.17  Coronal, T1-weighted MRI of hips with ligaments.

Fovea capitis

S

Iliacus muscle Ligamentum teres

Superior acetabular labrum

Iliofemoral ligament

Obturator internus muscle

Inferior acetabular labrum

Ischiofemoral ligament L

R Femoral neck

Transverse acetabular ligament

Obturator externus muscle

I

FIG. 10.18  Coronal, T1-weighted MRI of hips with ligaments and labrum.

abridges the acetabular notch, it transforms it into the acetabular foramen, which allows nerves and blood vessels to pass to and from the hip joint. The iliofemoral ligament is among the strongest of the body, with a major stabilizing function as it spans from the anterior inferior iliac spine and rim of the acetabulum to insert on the intertrochanteric line of the femur (Figs. 10.13 and 10.14). A primary function of this ligament is to provide a thick reinforcement to the anterior part of the hip

joint. The ischiofemoral and pubofemoral ligaments, although difficult to distinguish, present a spiral configuration of femoral attachment (Figs. 10.13 and 10.14). The ischiofemoral ligament arises from the ischium and courses in a spiral above the femoral neck to insert on the posterior femoral neck, making it the only ligament located on the posterior aspect of the hip. The pubofemoral ligament arises from the superior pubic ramus to radiate and insert onto the iliofemoral

CHAPTER 10  Lower Extremity

668

S Ilium Acetabulum

Piriformis muscle Gluteus maximus muscle

Iliopsoas muscle Femoral head

Ischial tuberosity

A

P

Obturator externus muscle

Posterior acetabular labrum Transverse acetabular ligament

I

FIG. 10.19  Sagittal, T1-weighted MRI of hip with ligaments and labrum.

S Ilium

Acetabulum Iliopsoas muscle

Gluteus maximus muscle

Anterior acetabular labrum

Superior gemellus muscle

Femoral head A

P Inferior gemellus muscle

Transverse acetabular ligament

Obturator externus muscle Quadratus femoris muscle

Zona orbicularis

I

FIG. 10.20  Sagittal, T1-weighted MRI of hip with transverse acetabular ligament.

CHAPTER 10  Lower Extremity

Femoral head

A

Iliofemoral ligament

Anterior acetabular labrum Anterior column Ligamentum teres

Joint capsule

Acetabular fat R

L

Posterior column

Posterior acetabular labrum

P

FIG. 10.21  Axial MR arthrogram of left hip. Femoral head Femoral neck

A

Anterior acetabular labrum

Iliofemoral ligament

Articular cartilage Acetabular fossa R

L Greater trochanter

Acetabulum Zona orbicularis

Posterior acetabular labrum

P

FIG. 10.22  Axial oblique MR arthrogram of left hip.

669

CHAPTER 10  Lower Extremity

670

S

Ilium Superior acetabular labrum

Femoral head

Zona orbicularis

R Obturator internus muscle

L Greater trochanter

Obturator externus muscle

Lesser trochanter

Ischium

I

FIG. 10.23  Coronal MR arthrogram of left hip with zona orbicularis.

Articular cartilage

S

Superior acetabular labrum

Femoral head Ligamentum teres

Zona orbicularis

R

L Femoral neck

Transverse acetabular ligament

Greater trochanter

Pubofemoral ligament Zona orbicularis

I

FIG. 10.24  Coronal MR arthrogram of left hip.

CHAPTER 10  Lower Extremity Articular cartilage

671

S

Ilium

Acetabulum Anterior column

Posterior column

A

P

Femoral head

Transverse acetabular ligament Ischium

I

FIG. 10.25  Sagittal MR arthrogram of hip with transverse acetabular ligament. Articular cartilage

Ilium

S

Ischiofemoral ligament

Anterior acetabular labrum

Posterior acetabular labrum

A

P Zona orbicularis

Femoral head

Femoral neck

Iliofemoral ligament

Lesser trochanter

I

FIG. 10.26  Sagittal MR arthrogram of hip with iliofemoral ligament.

ligament and intertrochanteric line. The spiral configuration of these two ligaments is unique to humans and ensures the stability and function while controlling the overall position of the lower limb. The ligamentum teres is a somewhat flattened band that extends from the fovea capitis of the femoral head to attach to the rim of the acetabular notch, as well as blend with the transverse

acetabular ligament (Figs. 10.12, 10.18, and 10.24). It is located entirely within the hip joint and contains nerves and vessels that pass to the head of the femur. Recent studies suggest the ligamentum teres may be a strong intrinsic stabilizer that can assist to prevent dislocation of the hip. Ligaments of the hip are identified in Figs. 10.12–10.26.

672

CHAPTER 10  Lower Extremity

Joint Capsule The joint capsule is composed of fibrous and synovial capsules. The fibrous capsule of the hip is strong and dense, being reinforced by the iliofemoral, ischiofemoral, and pubofemoral ligaments. It forms a sleeve that encloses the hip joint and most of the neck of the femur. Proximally, it is attached to the edge of the acetabulum, just distal to the acetabular labrum, and to the transverse acetabular ligament. Distally, the fibrous capsule is attached to the femoral neck, intertrochanteric line, and the greater trochanter, anteriorly. Posteriorly, it attaches to the neck, just proximal to the intertrochanteric crest (Figs. 10.5 and 10.21). The capsule consists of deep circular fibers that form the zona orbicularis, a sling or collar around the femoral neck that constricts the capsule and helps hold the femoral head in the acetabulum (Figs. 10.20, 10.22–10.24, and 10.26). The synovial capsule of the hip joint lines the internal surface of the fibrous capsule. The synovial capsule forms a sleeve for the ligamentum teres, lines the acetabular fossa, and covers the fat pad in the acetabular notch (Fig. 10.5). It is attached to the edges of the acetabular fossa and to the transverse acetabular ligament. The synovial capsule protrudes inferior to the fibrous capsule on the posterior aspect and forms the obturator externus bursa, which protects the tendon of the obturator externus muscle (Fig. 10.14).

Bursae There are many bursae located around the hip owing to the number of muscles associated with this joint. The hip bursae vary in number and position and act to reduce friction at locations where tendons and muscle pass over bone. Major bursae of the hip include the trochanteric, iliopsoas,

and ischial. The trochanteric (subgluteus maximus) bursa is located between the insertion site of the gluteus muscles, the vastus lateralis muscle, and the greater trochanter of the femur. The iliopsoas (iliopectineal) bursa is situated between the iliopsoas tendon and the lesser trochanter of the femur. Located between the ischial tuberosity and the gluteus maximus muscle is the ischial bursa (Fig. 10.27).

Snapping hip syndrome is a condition characterized by a snapping or popping sensation when the hip is flexed and extended and may cause discomfort or pain. The most common cause of the snapping sound is due to tendons catching on bony prominences with movement of the hip. The hip bursae, greater trochanteric, and iliopsoas may become inflamed with this syndrome and result in pain caused by bursitis.

Muscles of the Hip and Thigh A complex arrangement of muscles around the hip joint and thigh produces the movements of the hip. They are described in this section as gluteal muscles and muscles of the thigh and are illustrated in Figs. 10.15–10.20 and 10.28–10.54 and Table 10.1. The muscles of the gluteal region and thigh muscles may be separated into compartments by thickened sheets of deep fascia, thus allowing muscles of the lower extremity to be classified according to specific compartments in which they are located, such as the gluteal compartment and the anterior, medial, and posterior thigh compartments.

Gluteal Compartment—Superficial Muscles  Gluteus maximus muscle Gluteus medius muscle Gluteus minimus muscle

Gluteus muscles Iliopsoas muscle Iliopsoas bursa Greater trochanter Trochanteric bursa

Lesser trochanter Ischial tuberosity Ischial bursa

Posterior view

Anterior view

FIG. 10.27  Hip bursae.

CHAPTER 10  Lower Extremity S

Gluteus medius

Gluteus maximus Adductor magnus Gracilis Iliotibial (IT) band L

R

Semitendinosus Long head Short head

Semimembranosus

Biceps femoris

Popliteal fossa Lateral head of gastrocnemius muscle

Medial head of gastrocnemius muscle

FIG. 10.28  Posterior view of superficial gluteal muscles, right hip,

and thigh.

Iliac crest Gluteus medius (cut)

Sacrum

Gluteus minimus

Superior gemellus

Piriformis

Obturator internus tendon L Inferior gemellus

joint and acts primarily as a powerful extensor of the hip. It also plays an important role in lifting, walking, and running. The gluteus maximus originates from the ilium, sacrum, and coccyx to insert just distal to the gluteal tuberosity of the greater trochanter (Figs. 10.28–10.36). The gluteus medius muscle is located on the lateral and upper part of the buttock. It originates from the iliac crest, just lateral to the gluteus maximus muscle, and is partially covered by the gluteus maximus muscle along its medial third. The gluteus medius muscle is fan-shaped as it spans from the iliac crest to insert on the superolateral aspect of the greater trochanter of the femur (Figs. 10.28–10.36). The gluteus minimus muscle is the smallest of the gluteal muscles. It is also fan-shaped and completely covered by the gluteus medius muscle. The upper attachment of the gluteus minimus muscle is from the gluteal surface of the ilium, just inferior to that of the gluteus medius muscle. Its tendon attaches to the anterosuperior aspect of the greater trochanter of the femur (Figs. 10.29– 10.36). The gluteus medius and minimus muscles act to abduct and medially rotate the thigh.

Gluteal Compartment—Deep Muscles 

I

S

673

R Obturator externus

Quadratus femoris

Gluteus maximus (cut)

I

FIG. 10.29  Posterior view of deep gluteal muscles, right hip, and thigh.

The muscles of the gluteal compartment are identified in Figs. 10.28–10.36, and their functions are presented in Table 10.1. The gluteus maximus muscle is the largest muscle in the body and most superficial of the gluteal muscle group. It is situated on the posterior aspect of the hip

Piriformis muscle Obturator internus muscle Obturator externus muscle Gemellus muscles Quadratus femoris muscle

The muscles of the gluteal compartment are identified in Figs. 10.28–10.36, and their functions are presented in Table 10.1.The deep muscles of the gluteal compartment are the main lateral rotators of the thigh at the hip joint and also act to stabilize the hip joint. The piriformis muscle originates from the inner surface of the sacrum between the sacral foramina. It passes laterally and anteriorly through the greater sciatic foramen to attach to the superior boundary of the greater trochanter of the femur (Figs. 10.29, 10.30, 10.32, and 10.35). The actions of the piriformis muscle include lateral rotation and abduction of the thigh. The obturator internus muscle is a thick, fan-shaped muscle that originates from the inner border of the obturator foramen and travels through the lesser sciatic foramen. At this point, it changes shape as it becomes tendinous and courses laterally to attach to the greater trochanter of the femur (Figs. 10.15, 10.18, 10.29, 10.33, and 10.36). Its primary actions are the same as those of the piriformis muscle: lateral rotation and abduction of the thigh. The obturator externus muscle arises from the outer border of the obturator foramen in the pelvis to essentially mirror the obturator internus muscle. It courses laterally around the posterior side of the neck of the femur to insert into the medial side of the greater trochanter and acts to laterally rotate the thigh (Figs. 10.18, 10.29, 10.30, 10.33, and 10.36).

CHAPTER 10  Lower Extremity

674

Ilium

Gluteus minimus Gluteus medius muscle muscle

S

Gluteus maximus muscle Iliopsoas muscle

Piriformis muscle Superior gemellus muscle

Femoral head

Obturator internus tendon

Sartorius muscle A

P Inferior gemellus muscle

Obturator externus muscle

Semimembranosus tendon Quadratus femoris muscle

Iliopsoas muscle

Conjoined tendon of long head biceps femoris and semitendinosus muscles

Rectus femoris muscle Pectineus muscle

I

Adductor magnus muscle

FIG. 10.30  Sagittal, T1-weighted MRI of hip with muscles. A Rectus abdominis muscle

Gluteus minimus muscle

Gluteus medius muscle

P

Gluteus maximus muscle

Psoas major muscle

Iliacus muscle

A

FIG. 10.31  Axial, T1-weighted MRI of gluteal muscles.

Sartorius muscle Tensor fasciae latae muscle

Rectus abdominis muscle Iliopsoas muscle Gluteus minimus muscle

Gluteus maximus muscle

P

Gluteus medius muscle

Piriformis muscle

FIG. 10.32  Axial, T1-weighted

MRI of piriformis and iliopsoas muscles.

CHAPTER 10  Lower Extremity

675

A

Sartorius muscle

Pectineus muscle

Rectus femoris muscle

Iliopsoas muscle

Tensor fasciae latae muscle Vastus lateralis muscle

Body of pubis

Iliotibial (IT) band Gluteus maximus muscle

Ischium

Obturator internus muscle

P

Obturator externus muscle

Quadratus femoris muscle

FIG. 10.33  Axial, T1-weighted MRI of obturator muscles. Psoas major muscle

A

Iliacus muscle

L

R

Gluteus maximus muscle

Rectus abdominis muscle

P

External oblique muscle

FIG. 10.34  Axial CT with psoas major and iliacus muscles.

Gluteus minimus muscle

Gluteus medius muscle

A Sartorius muscle

Rectus abdominis muscle

Tensor fasciae latae muscle Iliopsoas muscle

Iliotibial (IT) band L

R

Gluteus maximus muscle

FIG. 10.35  Axial CT with iliopsoas muscle.

Piriformis muscle

P

Gluteus minimus muscle

Gluteus medius muscle

676

CHAPTER 10  Lower Extremity Obturator externus muscle

Pectineus muscle

Pubic bone

Iliopsoas muscle

A

Sartorius muscle

Rectus femoris muscle

Tensor fasciae latae muscle

Iliotibial (IT) band Vastus lateralis muscle

Gluteus medius muscle

Femur

Quadratus femoris muscle

Obturator internus muscle

Gluteus maximus muscle

P

Rectum

Levator ani muscle

Ischium

FIG. 10.36  Axial CT with gluteus and obturator muscles.

The two gemellus muscles (superior and inferior) are located along the superior and inferior boundaries of the obturator internus muscle and tendon (Fig. 10.29). The superior gemellus muscle arises from the ischial spine, whereas the inferior gemellus muscle arises from the ischial tuberosity. Both muscles join with the tendon of the obturator internus muscle to insert into the medial surface of the greater trochanter (Figs. 10.15, 10.16, 10.20, 10.29, and 10.30). The

TABLE 10.1 Muscle

gemellus muscles also act to laterally rotate and abduct the thigh. The rectangular quadratus femoris muscle is located inferior to the obturator internus and gemellus muscles. It arises from the lateral border of the ischial tuberosity and then courses laterally to insert on the intertrochanteric crest of the femur. The primary action of the quad­ ratus femoris muscle is lateral rotation of the thigh (Figs. 10.29, 10.30, 10.33, and 10.36).

  Muscles of the Gluteal Compartment Proximal Insertion

Distal Insertion

Action

Gluteal tuberosity of greater trochanter Superolateral aspect of greater trochanter Anterosuperior aspect of greater trochanter

Extensor of the hip; maintains erect position of the body Abducts and medially rotates the thigh

Superior boundary of greater trochanter Greater trochanter

Lateral rotation and abduction of the thigh Lateral rotation and abduction of the thigh Lateral rotation of the thigh Lateral rotation and abduction of the thigh Lateral rotation and abduction of the thigh Lateral rotation of the thigh

Superficial Muscles of the Gluteal Compartment Gluteus maximus

Ilium, sacrum, coccyx

Gluteus medius

Iliac crest

Gluteus minimus

Gluteal surface of ilium

Deep Muscles of the Gluteal Compartment Piriformis Sacrum Obturator internus

Inner border of obturator foramen

Obturator externus Superior gemellus

Outer border of obturator foramen Ischial spine

Inferior gemellus

Ischial tuberosity

Quadratus femoris

Lateral border of ischial tuberosity

Greater trochanter, medial side Joins with tendon of obturator internus, medial surface greater trochanter Joins with tendon of obturator internus, greater trochanter Intertrochanteric crest of femur

Abducts and medially rotates the thigh

CHAPTER 10  Lower Extremity

Muscles of the Anterior Thigh Compartment  Iliopsoas muscle Sartorius muscle Quadriceps femoris muscle Tensor fasciae latae muscle

The muscles of the anterior thigh compartment are shown in Figs. 10.30–10.54 and described in Table 10.2. These muscles act both to flex the hip joint and extend the knee joint. The powerful iliopsoas muscle is composed of the psoas major and iliacus muscles (Figs. 10.30, 10.34, 10.35, and 10.37). The psoas major muscle arises from the transverse processes of the lumbar vertebrae and courses inferiorly within the pelvis. It exits the pelvis as it courses under the inguinal ligament to enter the anterior compartment of the thigh. The tendon of the psoas major joins with the tendon of the iliacus muscle to pass anterior to the hip joint

capsule and attach to the lesser trochanter of the femur (Fig. 10.37). The iliacus muscle arises from the iliac fossa and courses along the lateral side of the psoas major muscle in the pelvis. These muscles act conjointly in flexing the thigh at the hip and stabilizing the hip joint (Fig. 10.37). The sartorius muscle is known as the longest muscle in the body; it extends from the anterior superior iliac spine to the medial surface of the tibia near the tuberosity (Figs. 10.37 and 10.40–10.54). It acts to flex, abduct, and laterally rotate the thigh. The quadriceps femoris muscle covers almost all of the anterior surface and sides of the femur. It originates as four heads (rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius) to create a powerful extensor of the knee (Figs. 10.37–10.54). The superior ends of the four heads of the quadriceps femoris muscle arise from different locations, but their inferior tendons merge to form the quadriceps femoris tendon that courses over the S

Twelfth thoracic vertebra

Twelfth rib Quadratus lumborum muscle Psoas minor muscle Iliac crest Iliopsoas muscle

Psoas major Iliacus

Fifth lumbar vertebra

Anterior superior iliac spine Pubis Tensor fasciae latae muscle

Pectineus muscle

Sartorius muscle Iliotibial (IT) band

R

L

Quadriceps femoris muscle

Adductor longus muscle Gracilis muscle Adductor magnus muscle

Rectus femoris Vastus lateralis Vastus medialis

677

Tendon of quadriceps femoris Patella Patellar ligament

Gerdy tubercle I

FIG. 10.37  Anterior view of thigh muscles.

678

CHAPTER 10  Lower Extremity S

S

Greater trochanter

Pectineus muscle (cut) Lesser trochanter

R Vastus lateralis muscle

Adductor brevis muscle

R

L

Adductor longus muscle

L

Vastus intermedius muscle

Quadratus femoris muscle

Vastus medialis muscle

Adductor magnus muscle

Femur

Quadriceps femoris tendon

Patella Patellar ligament

I

I

FIG. 10.38  Anterior view of quadriceps muscles.

Vastus medialis muscle

FIG. 10.39  Anterior view of adductor muscles.

A

Rectus femoris muscle

Sartorius muscle Branches of femoral nerve

Vastus lateralis muscle

Long saphenous vein

Vastus intermedius muscle

Femoral artery Femoral vein R

Adductor longus muscle Profunda femoris artery and veins

L

Femur

Obturator nerve Adductor brevis muscle

Sciatic nerve Gluteus maximus muscle

Gracilis muscle

Adductor magnus muscle

P

Semimembranosus tendon Biceps femoris muscle (long head) and semitendinosus muscle

FIG. 10.40  Axial view of right femur, proximal one-third.

CHAPTER 10  Lower Extremity Vastus lateralis muscle Vastus intermedius muscle

679

Rectus femoris muscle A Vastus medialis muscle Nerve to vastus medialis muscle

Femur

Sartorius muscle Saphenous nerve

Profunda femoris artery R

Biceps femoris muscle (short head)

Femoral artery in adductor canal

L

Femoral vein Long saphenous vein

Sciatic nerve

Adductor longus muscle

Biceps femoris muscle (long head)

Adductor magnus muscle

Semitendinosus muscle

Gracilis muscle P Posterior femoral cutaneous nerve

Semimembranosus tendon

FIG. 10.41  Axial view of right femur, midthigh.

Quadriceps femoris tendon

A

Infrapatellar fat

Suprapatellar bursa Vastus medialis muscle

Femur Descending genicular artery

Vastus lateralis muscle R

Popliteal artery

L

Popliteal vein

Adductor magnus tendon

Biceps femoris muscle Sciatic nerve

Saphenous nerve

Sartorius muscle Long saphenous vein

Common peroneal nerve

Gracilis tendon

Tibial nerve Short saphenous vein Posterior femoral cutaneous nerve

P

Semimembranosus muscle Semimembranosus tendon

FIG. 10.42  Axial view of right femur, distal one-third.

patella and continues as the patellar ligament in the knee to insert on the tibial tuberosity (Fig. 10.37). The rectus femoris originates from the anterior inferior iliac spine, the vastus lateralis from the greater trochanter and lateral lip of the linea aspera of the femur, the vastus medialis from the intertrochanteric line and medial lip of the linea aspera of the femur, and the vastus intermedius from the anterior and lateral surfaces of the body of the femur

(Figs. 10.44 and 10.47). All the parts of the quadriceps femoris act to extend the leg at the knee joint and, through the actions of the rectus femoris, flex the hip joint. The tensor fasciae latae muscle is a short, thick, teardropshaped muscle located on the anterolateral aspect of the thigh, enclosed between two layers of the fascia. As its name implies, it tightens the lateral fascia, thereby enabling the thigh muscles to act with increased power. It abducts,

680

CHAPTER 10  Lower Extremity Rectus femoris muscle

A

Sartorius Vastus muscle medialis muscle

Tensor fasciae latae muscle

Femoral artery and vein

Vastus lateralis muscle

Adductor longus muscle

Vastus intermedius muscle

Great saphenous vein

Femur

Adductor brevis muscle

Iliotibial (IT) band R

L Gracilis muscle

Sciatic nerve

Adductor magnus muscle

Biceps femoris muscle (long head)

Semimembranosus tendon

Gluteus maximus muscle

Semitendinosus muscle

P

FIG. 10.43  Axial, T1-weighted MRI of right proximal femur.

Vastus lateralis muscle

A

Rectus femoris muscle

Vastus medialis muscle Femoral vein

Vastus intermedius muscle

Femoral artery

Femur

Sartorius muscle

Linea aspera

Adductor longus muscle

Profunda femoris artery

Great saphenous vein L

R Biceps femoris muscle (short head)

Gracilis muscle

Biceps femoris muscle (long head)

Adductor magnus muscle Sciatic nerve

Semitendinosus muscle

Semimembranosus muscle P

FIG. 10.44  Axial, T1-weighted MRI of right mid-femur.

CHAPTER 10  Lower Extremity Vastus lateralis muscle

A

Rectus femoris muscle

Vastus Intermedius muscle Vastus medialis muscle

Femur

Popliteal vein Popliteal artery R

L

Biceps femoris muscle (short head)

Sartorius muscle Adductor magnus muscle

Sciatic nerve

Gracilis muscle

Biceps femoris muscle (long head)

Semitendinosus muscle

P

Semimembranosus muscle

FIG. 10.45  Axial, T1-weighted MRI of right distal femur.

Tensor fasciae latae muscle

Rectus femoris muscle

A

Femoral artery and vein

Sartorius muscle Adductor longus muscle

Vastus intermedius muscle

Profunda femoris artery and vein

Vastus medialis muscle Vastus lateralis muscle

Adductor brevis muscle Gracilis muscle

R

L Adductor magnus muscle Semimembranosus tendon Semitendinosus muscle Gluteus maximus muscle

P

Sciatic nerve

FIG. 10.46  Axial CT of right proximal femur.

681

682

CHAPTER 10  Lower Extremity Rectus femoris muscle

A

Vastus medialis muscle Adductor longus muscle Femoral artery

Vastus lateralis muscle Vastus intermedius muscle

Sartorius muscle L

R

Gracilis muscle

Linea aspera

Adductor magnus muscle Biceps femoris muscle (long head)

Semitendinosus muscle

P

Semimembranosus muscle

FIG. 10.47  Axial CT of right mid-femur. Femur

A

Vastus intermedius muscle

Vastus medialis muscle

Vastus lateralis muscle

Popliteal artery Adductor magnus muscle

Iliotibial (IT) band R

L

Popliteal vein Sartorius muscle

Biceps femoris muscle (short head) Sciatic nerve

Gracilis muscle

Biceps femoris muscle (long head) Semitendinosus muscle

P

Semimembranosus muscle

FIG. 10.48  Axial CT of right distal femur. medially rotates, and flexes the thigh and helps keep the knee extended. It originates from the anterior superior iliac spine and anterior part of the iliac crest and ends where the muscle inserts in the iliotibial band (Figs. 10.32, 10.33, 10.35–10.37, and 10.43). The iliotibial (IT) band is a long, wide band of fascia that lies over the muscles on the outer surface of the thigh. This band is a thickening of the normal

fascia that surrounds the entire leg. It arises from tendinous fibers of the tensor fasciae latae and the gluteus maximus muscles. Acting almost like a ligament, this tendon helps mainly to stabilize the knee joint but also acts in flexing and extending the knee. It extends downward to insert on the lateral condyle of the tibia at Gerdy tubercle (Figs. 10.6, 10.37, 10.43, and 10.49).

CHAPTER 10  Lower Extremity

Tensor fasciae latae muscle

S

Iliopsoas muscle

Gluteus minimus muscle

Pectineus muscle Adductor brevis muscle

S

Ilium

683

Obturator internus muscle

Gluteus medius muscle

Bladder Obturator externus muscle

Femoral head

Pectineus muscle

Adductor longus muscle

Iliotibial (IT) band

Gracilis muscle

Vastus lateralis muscle

Vastus lateralis muscle R

L Sartorius muscle

Adductor brevis muscle

L

R

Gracilis muscle

Vastus intermedius muscle

Adductor magnus muscle

Rectus femoris muscle Vastus medialis muscle

Adductor longus muscle

Sartorius muscle

Femur

Vastus medialis muscle

Quadriceps femoris tendon

I

FIG. 10.49  Coronal, T1-weighted MRI of anterior thigh muscles.

Muscles of the Medial Thigh Compartment  Gracilis muscle Pectineus muscle Adductor longus muscle Adductor brevis muscle Adductor magnus muscle

The muscles of the medial thigh compartment are shown in Figs. 10.37–10.54 and described in Table 10.2. Adduction is the primary action of the medial thigh muscles. The long, straplike gracilis muscle lies along the medial side of the thigh and knee. The gracilis muscle extends from the inferior pubic ramus and pubic symphysis and is the only medial thigh muscle to cross the knee joint as it inserts onto the anterior surface of the tibia just inferior to the medial condyle. In addition to

I

FIG. 10.50  Coronal, T1-weighted MRI of right hip and thigh muscles. adducting the thigh, the gracilis muscle acts to flex the leg and helps medially rotate the thigh (Figs. 10.37 and 10.40–10.51). Arising from the pectineal line of the pubis is the short, flat pectineus muscle. It lies medial to the psoas major muscle in the superior thigh, then narrows as it courses inferiorly to insert on the medial lip of the linea aspera, at the pectineal line, distal to the lesser trochanter of the femur. It acts to adduct and flex the thigh (Figs. 10.33, 10.36, 10.37, 10.49, and 10.50). The adductor muscle group, as named, acts to adduct the thigh and is composed of three muscles: the adductor longus, adductor brevis, and adductor magnus (Figs. 10.39–10.50). These muscles originate on the body and inferior pubic ramus and fan out to insert along the length of the medial aspect of the femur.

684

CHAPTER 10  Lower Extremity S

Ischium

Quadratus femoris muscle

Adductor magnus muscle

Semitendinosus muscle

R Biceps femoris muscle (short head)

L

Vastus lateralis muscle

Gracilis muscle

Semimembranosus muscle

Biceps femoris muscle (long head)

I

FIG. 10.51  Coronal, T1-weighted MRI of posterior thigh muscles.

S Ilium Obturator internus muscle

Pectineus muscle

Obturator externus muscle

Adductor brevis muscle

Ischium Gluteus maximus muscle

Adductor longus muscle

Quadratus femoris muscle A

P Adductor magnus muscle

Semitendinosus muscle

Sartorius muscle

Vastus medialis muscle I

FIG. 10.52  Sagittal, T1-weighted MRI of medial thigh muscles.

CHAPTER 10  Lower Extremity Iliofemoral ligament

S

Femoral Superior gemellus head muscle Obturator internus tendon

Iliopsoas muscle

Inferior gemellus muscle

Sartorius muscle

Quadratus femoris muscle

Adductor longus muscle

P

A

Gluteus maximus muscle Adductor magnus muscle Semitendinosus muscle

Vastus medialis muscle

Semimembranosus muscle

I

FIG. 10.53  Sagittal, T1-weighted MRI of hip and thigh muscles.

Gluteus medius muscle

S

Gluteus maximus muscle

Femoral neck

Obturator internus tendon Greater trochanter

Rectus femoris muscle

Quadratus femoris muscle A

P Adductor magnus muscle

Vastus intermedius muscle

Biceps femoris muscle (long head) Biceps femoris muscle (short head) Femur I

FIG. 10.54  Sagittal, T1-weighted MRI of lateral thigh muscles.

685

686

CHAPTER 10  Lower Extremity

TABLE 10.2 Muscle Anterior Thigh Psoas major Iliacus Sartorius

Muscles of the Thigh Proximal Insertion

Distal Insertion

Action

Transverse processes of lumbar vertebrae Iliac fossa Anterior superior iliac spine and iliac crest Anterior superior iliac spine

Lesser trochanter

Flexes the thigh at hip and stabilizes the hip joint Flexes the thigh at hip and stabilizes the hip joint Flexes, abducts, and laterally rotates the thigh

Lesser trochanter Medial surface of tibia near tuberosity

Tensor fasciae latae Quadriceps Femoris Rectus femoris Anterior inferior iliac spine

Iliotibial (IT) band

Abducts, medially rotates, and flexes the thigh; helps maintain extension of the knee

Tibial tuberosity via patellar ligament

Vastus lateralis

Tibial tuberosity via patellar ligament

Extends the leg at knee joint and flexes the hip joint Extends leg at knee joint

Tibial tuberosity via patellar ligament

Extends leg at knee joint

Tibial tuberosity via patellar ligament

Extends leg at knee joint

Anterior surface of tibia just inferior to medial condyle Medial lip of linea aspera and lesser trochanter Middle third of linea aspera Superior linea aspera and posterior surface of proximal femur Posterior surface of proximal femur, linea aspera, and adductor tubercle of medial condyle of knee

Adducts thigh, flexes leg, and medially rotates thigh Adducts and flexes the thigh

Vastus medialis Vastus intermedius Medial Thigh Gracilis

Greater trochanter and lateral lip of linea aspera Intertrochanteric line and medial lip of linea aspera Anterior and lateral surfaces of femoral body

Pectineus

Inferior pubic ramus and pubic symphysis Pectineal line of pubis

Adductor longus Adductor brevis

Body and inferior pubic ramus Body and inferior pubic ramus

Adductor magnus

Body and inferior pubic ramus

Posterior Thigh Hamstrings Semitendinosus

Ischial tuberosity

Anterior tibia, medial side

Semimembranosus

Ischial tuberosity

Medial condyle of tibia, posterior aspect

Biceps femoris

Long head: ischial tuberosity Short head: lateral lip of linea aspera

Lateral surface of fibular head and lateral tibial condyle

The adductor longus muscle is the most anterior muscle in the adductor group and attaches to the middle third of the linea aspera of the femur. The shorter adductor brevis muscle lies deep to the pectineus and adductor longus muscles. Its distal attachment is between the lesser trochanter and superior end of the linea aspera of the femur. The largest and most medial of the adductor group is the adductor magnus muscle. It is situated posterior to the adductor brevis and adductor longus and anterior to the semitendinosus and semimembranosus muscles. It forms a large triangular sheet of muscle in the thigh and is composed of two parts, an adductor part and a hamstring part. The adductor portion of the adductor magnus has an extensive distal attachment on the linea aspera of the femur, whereas the hamstring part attaches to the adductor tubercle on top of the medial condyle of the femur.

Adducts the thigh Adducts the thigh Adducts the thigh

Extend the thigh, flex and medially rotate the leg, and extend the trunk when hip and knee are flexed Extend the thigh, flex and medially rotate the leg, and extend the trunk when hip and knee are flexed Flex the leg at the knee and laterally rotate the leg when hip is flexed

Muscles of the Posterior Thigh Compartment  Semitendinosus muscle Semimembranosus muscle Biceps femoris muscle

The muscles of the posterior thigh compartment are shown in Figs. 10.28, 10.40–10.48 and 10.51–10.54 and described in Table 10.2. The semitendinosus, semimembranosus, and biceps fe­moris muscles are collectively known as the hamstrings. They make up the large mass of muscles that can be palpated on the posterior aspect of the thigh and are involved with extension of the hip, flexion of the knee, and rotation of the flexed knee. The semitendinosus muscle extends from the ischial tuberosity, courses on the medial aspect of the femur, then continues inferiorly around the medial tibial condyle and attaches to the medial side of the anterior tibial

CHAPTER 10  Lower Extremity surface (Figs. 10.28, 10.40–10.48, and 10.52–10.54). It acts to extend the thigh, flex and medially rotate the leg, and extend the trunk when the thigh and leg are flexed. The semimembranosus muscle also originates from the ischial tuberosity but attaches to the posterior part of the medial condyle of the tibia (Figs. 10.28, 10.40–10.48, and 10.52–10.54). Along with the semitendinosus muscle, it acts to extend the thigh, flex and medially rotate the leg, and extend the trunk when the thigh and leg are flexed. The biceps femoris muscle, as named, has two heads (long and short). The long head extends from the ischial tuberosity, whereas the short head extends from the lateral lip of the linea aspera of the femur. The biceps femoris muscle extends inferiorly over the lateral part of the posterior surface of the knee to insert on the lateral surface of the fibular head and lateral tibial condyle (Figs. 10.48, 10.51, and 10.54). It acts to flex the leg at the knee joint and laterally rotates the leg when the leg is flexed.

KNEE AND LOWER LEG Bony Anatomy The bones that contribute to the knee joint and lower leg are the femur, tibia, patella, and fibula (Figs. 10.55 and 10.56). Cartilage covers the articular surfaces of the femur, tibia, and patella and helps provide smooth movement within the knee joint.

Distal Femur.  The distal portion of the femur broadens

back, whereas the medial femoral condyle remains more consistent in width. The femoral condyles are anteriorly connected by the smooth patellar surface and posteriorly separated by the intercondylar fossa (Figs. 10.9, 10.57, and 10.58). On the side of each condyle is a raised edge called the medial and lateral epicondyle for the attachment of ligaments and muscles (Figs. 10.59 and 10.60). A small projection located above the medial epicondyle is the adductor tubercle, which serves as an attachment for a portion of the adductor magnus muscle (Figs. 10.9 and 10.11). On the posterior surface of the distal femur is a triangular area called the popliteal surface. The base of the triangle is located at the intercondylar line, which marks the beginning of the intercondylar fossa. The sides of the triangle are formed by the medial and lateral supracondylar lines, which are continuations of the linea aspera (Figs. 10.9 and 10.11).

Tibia.  The tibia has a widened proximal end that has

two cartilage-covered projections: the medial and lateral condyles (Fig. 10.62). The superior articular surface of both condyles has flattened surfaces called tibial plateaus for articulation with the femoral condyles (Figs. 10.62 and 10.63). The tibial condyles are separated by the intercondylar eminence (tibial spine), which ends in two peaks called the medial and lateral intercondylar tubercles. The intercondylar tubercles and the roughened areas around them serve as attachment sites for the cruciate ligaments and meniscus (Figs. 10.55, 10.56, 10.59, and 10.62). The lateral tibial condyle has a small articular

into two articular cartilage-covered projections called the medial and lateral condyles (Figs. 10.9, 10.55–10.61). The lateral femoral condyle is wider in front than in the Femur

687

S

Femur

S Base of patella Medial epicondyle

Patella Medial condyle

Lateral condyle

Medial tibial plateau Tibial tuberosity

Intercondylar eminence Gerdy tubercle L

R

Lateral epicondyle Apex of patella

Medial condyle

Lateral condyle

Medial intercondylar tubercle

L

R

Tibial plateau

Lateral intercondylar tubercle Gerdy tubercle

Tibia Fibula

Tibial tuberosity

Fibula

I

I

FIG. 10.55  Anterior view of left knee joint.

FIG. 10.56  3D CT of right knee joint.

688

CHAPTER 10  Lower Extremity Lateral patellar retinaculum

Patellar ligament

A

Patellofemoral joint Patella

Medial patellar retinaculum Medial femoral condyle

IT band

Medial collateral ligament

Lateral femoral condyle

Sartorius muscle L

R Anterior cruciate ligament

Posterior cruciate ligament

Biceps femoris muscle

Gracilis tendon

Plantaris muscle

Semimembranosus tendon

Gastrocnemius muscle (lateral head) Popliteal Intercondylar artery fossa

P

Gastrocnemius muscle (medial head)

Semitendinosus tendon

FIG. 10.57  Axial, T1-weighted MRI of distal right femur.

Patella

A

Patellofemoral joint

Patellar surface

Lateral femoral condyle L

R Medial femoral condyle

Intercondylar fossa

P

FIG. 10.58  Axial CT of left distal femur.

CHAPTER 10  Lower Extremity

S

Medial femoral condyle

S

Lateral femoral condyle

689

Ilium

Lateral epicondyle

Acetabulum Femoral neck Greater trochanter

Femoral head

R

L Femoral shaft

L

R

Medial epicondyle

Lateral epicondyle Medial Intercondylar fossa epicondyle

Intercondylar eminence

I

Lateral tibial plateau

Fibula

FIG. 10.59  Coronal, T1-weighted MRI of left knee joint.

Medial femoral condyle

Lateral femoral condyle I

FIG. 10.60  Coronal CT reformat of right femur. surface called the articular fibular surface, which articulates with the head of the fibula, creating the proximal tibiofibular joint (Figs. 10.62 and 10.64). The shaft of the tibia is triangular with a sharp anterior edge or crest that contains a bony projection called the tibial tuberosity for the attachment of the patellar ligament (Figs. 10.65 and 10.66). Lateral and superior to the tibial tuberosity is the attachment site for the iliotibial (IT) band, a roughened area of the lateral tibial condyle commonly called Gerdy tubercle (Figs. 10.37 and 10.56). The tibiofibular joint the shaft lies directly beneath the skin and is devoid of muscle, whereas the lateral surface serves as the attachment site for the interosseous membrane. The posterior surface

has an obliquely oriented bony ridge called the soleal (popliteal) line, which provides attachment to tendon fibers of the soleus muscle (Fig. 10.62). The distal tibia has a flattened articular end with a medial extension that forms the medial malleolus, which articulates with the talus (Figs. 10.62, 10.67, and 10.68). The posterior surface of the medial malleolus has a small indentation, the malleolar groove, for the passage of the tibialis posterior and flexor digitorum longus tendons (Fig. 10.62). On the lateral side of the distal tibia is a shallow indentation called the fibular notch, which articulates with the distal fibula, forming the distal tibiofibular articulation (Fig. 10.62).

CHAPTER 10  Lower Extremity

690

S Quadriceps tendon

Patella Lateral femoral condyle A

P Gastrocnemius muscle (lateral head)

Lateral meniscus, anterior horn

Arcuate popliteal ligament Lateral meniscus, posterior horn

Tibia

Tibial plateau

Tibialis anterior muscle

Fibula I

FIG. 10.61  Sagittal MRI of knee with meniscus and ligaments. Gerdy tubercle Intercondylar Medial tibial Lateral tibial eminence plateau plateau Medial Lateral condyle condyle

Proximal tibiofibular joint

Head of fibula

Tibial tuberosity Soleal (popliteal) line Interosseous membrane

Fibula

Anterior crest

Fibula

A

Medial meniscus (anterior horn)

Lateral meniscus (anterior horn)

Tibia

Medial tibial plateau

Lateral tibial plateau

R

Distal tibiofibular joint Lateral malleolus

Fibular notch

Medial malleolus

Lateral malleolus

Malleolar groove Articular surface

Infrapatellar fat pad

Patellar ligament

Malleolar fossa

FIG. 10.62  Tibia and fibula. Left, Anterior view. Right, Posterior view.

L

Anterior cruciate ligament

Saphenous vein Sartorius muscle

Popliteal artery Popliteal vein

Posterior cruciate ligament P

FIG. 10.63  Axial, T1-weighted MRI of right knee with tibial plateau.

CHAPTER 10  Lower Extremity Extensor digitorum longus muscle

Tibialis anterior muscle

A

Patellar ligament

Tibial tuberosity

Tibiofibular articulation

Tibia

Interosseous membrane

Sartorius tendon

Peroneus longus muscle

Gracilis tendon

Fibular head

Pes anserinus

L

R

Semitendinosus tendon

Soleus muscle

Popliteus muscle Gastrocnemius muscle (lateral head)

Gastrocnemius muscle (medial head)

Popliteal artery

P

Popliteal vein

Tibial nerve

FIG. 10.64  Axial, T1-weighted MRI of right knee with tibiofibular articulation.

S Quadriceps tendon Femur

Base Patellar articular cartilage

Patella A

P

Apex

Posterior cruciate ligament

Patellar ligament Tibial tuberosity Tibia I

FIG. 10.65  Midsagittal, T1-weighted MRI of tibia.

691

CHAPTER 10  Lower Extremity

692

S

Femur

Patella Patellar ligament Tibial tuberosity

A

P Tibial shaft

Calcaneus Talus

I

Sinus tarsi

Extensor hallucis longus tendon

A

FIG. 10.66  Midsagittal, CT reformat of tibia.

Great Tibialis anterior saphenous vein tendon

Extensor digitorum longus tendon

Deltoid ligament Talus Medial malleolus

Extensor retinaculum

Tibialis posterior tendon

Anterior talofibular ligament L

R

Flexor digitorum longus tendon

Talocrural joint

Flexor retinaculum

Lateral malleolus

Flexor hallucis longus muscle and tendon

Posterior talofibular ligament

Plantaris tendon

Peroneus longus tendon

Achilles tendon

Peroneus brevis muscle and tendon

P Posterior tibiofibular ligament

FIG. 10.67  Axial, T1-weighted MRI of right ankle with malleoli.

CHAPTER 10  Lower Extremity

693

A

Talus Medial malleolus R

L Lateral malleolus

FIG. 10.68  Axial CT of left ankle with malleoli.

P

Fibula.  The fibula is a long, relatively thin bone that has

expanded proximal and distal ends. The majority of its length is covered by muscles. The proximal end is the head, which ends in a sharp superior apex. Medially, it has an articular surface for articulation with the lateral condyle of the tibia (Figs. 10.62 and 10.64). The distal end forms the lateral malleolus, which extends farther distally than the medial malleolus of the tibia (Figs. 10.62, 10.67, and 10.68). The medial surface of the lateral malleolus has an articular facet that articulates with the talus. Posterior to the malleolar articular surface is a small cavity called the malleolar fossa, which is where the posterior talofibular ligament is anchored (Figs. 10.62 and 10.67).

Patella and Patellofemoral Joint.  The patella is

the largest sesamoid bone in the body and is embedded within the quadriceps tendon. It is a flat, triangular bone with a proximal broad base and a distally pointed apex (Fig. 10.69). The patella has an anterior and posterior surface and three borders: superior, medial, and lateral. The base of the patella has roughened areas for the attachment of the rectus femoris and vastus intermedius muscles, whereas the roughened medial and lateral borders receive attachment for the vastus medialis and lateralis muscles. The posterior surface is covered with the thickest articular cartilage found in the body and is centrally divided by a broad vertical ridge into medial and lateral facets. The larger lateral facet articulates with the lateral femoral condyle, and the smaller medial facet articulates with the medial femoral condyle (Fig. 10.70). The patella protects the anterior joint surface of the knee and functions to increase the leverage of the quadriceps extensor system (Figs. 10.55–10.58, 10.65, and 10.66).

Anterior Base

Apex Lateral facet Medial facet Vertical ridge

Surface for patellar ligament Posterior

FIG. 10.69  Patella. Top, Anterior view. Bottom, Posterior view.

A

Medial facet

Lateral facet

Vertical ridge

Lateral condyle of the femur

Medial condyle of the femur

P Intercondylar fossa

FIG. 10.70  Patellofemoral joint with intercondylar fossa of femur.

CHAPTER 10  Lower Extremity

694

Knee Joint The knee is the largest and one of the most complex joints of the body. The bones that contribute to the knee joint are the femur, tibia, and patella (Figs. 10.55 and 10.56). The knee has three separate articulations: two femorotibial and a patellofemoral articulation within the same synovial membrane. A supporting network of menisci, ligaments, tendons, fasciae, and muscles functions together to meet the demands made on the knee (Figs. 10.71–10.77).

Joint Capsule.  The joint capsule of the knee consists of a strong, fibrous membrane that is medially, laterally, and posteriorly reinforced by extracapsular ligaments.

These include the patellar, lateral (fibular) collateral, medial (tibial) collateral, oblique popliteal, and arcuate ligaments. Anteriorly, the capsule blends with the quadriceps tendon and the medial and lateral retinacula (Figs. 10.77–10.80). The synovial membrane of the knee is the largest and most extensive synovial cavity in the body. It lines the inner surface of the fibrous membrane attaching to the articular margins of the femur, tibia, and patella. It is reflected across the anterior surface of the cruciate ligaments, so they are located intracapsular but extrasynovial (Fig. 10.71). Synovial recesses can be found close to the patella and popliteus tendon, and behind each femoral condyle. They may appear like a pouch, extending beyond the articular margin of the femoral condyles.

Femur Quadriceps femoris tendon

Suprapatellar bursa Synovial membrane of joint capsule Fibrous membrane of joint capsule

Iliotibial (IT) band

Tibial collateral ligament Infrapatellar fold Posterior cruciate ligament

Fibular collateral ligament

Anterior cruciate ligament Popliteus tendon

Medial femoral condyle

Lateral femoral condyle

Semimembranosus tendon

Posterior meniscofemoral ligament

Posterior cruciate ligament

Lateral collateral ligament Popliteus tendon Medial collateral ligament

Subpopliteal recess

Medial meniscus

Head of fibula

Anterior cruciate ligament

Lateral meniscus

Synovial membrane of joint capsule Fibrous membrane of joint capsule Iliotibial (IT) band

Alar fold

Infrapatellar fat

Infrapatellar fold

Fibula

Patellar ligament Tibia

FIG. 10.71  Knee joint (anterosuperior view).

CHAPTER 10  Lower Extremity

Menisci.  Located between the femoral condyles and

collateral ligament, making it far less mobile than the lateral meniscus. The lateral meniscus almost forms a closed ring with anterior and posterior horns of approximately the same width (Fig. 10.73). Two ligaments arise from the posterior horn of the lateral meniscus. The posterior meniscofemoral ligament (ligament of Wrisberg) passes behind the posterior cruciate ligament to attach to the medial femoral condyle (Figs. 10.75 and 10.78). The anterior meniscofemoral ligament (ligament of Humphry) connects the posterior horn to the medial condyle, passing in front of the posterior cruciate ligament (Fig. 10.73). The two menisci are connected anteriorly by the transverse ligament (Figs. 10.72, 10.73, and 10.79).

tibial plateaus are the paired menisci (Figs. 10.72– 10.79). These C-shaped menisci, composed of fibrous connective tissue, cushion the articulation between the femoral condyles and tibial plateaus and are commonly divided into anterior and posterior horns. In crosssection they appear wedge-shaped, with a thickened outer margin that flattens medially (Figs. 10.73, 10.74, and 10.76). Their outer margins fuse with the joint capsule, and their anterior and posterior horns attach to the intercondylar eminence of the tibia. The menisci differ in size and shape. The medial meniscus is crescent-shaped, with the posterior horn being wider than the anterior horn. The medial meniscus is attached to the medial S

Posterior cruciate ligament

Anterior cruciate ligament Lateral collateral ligament

Medial collateral ligament Medial meniscus

Lateral meniscus

Transverse ligament

Patellar ligament

Fibula Patella Quadriceps tendon (cut and retracted) I

FIG. 10.72  Anterior view of meniscus and ligaments of knee. A Anterior horn of medial meniscus

Transverse ligament Anterior horn of lateral meniscus Lateral meniscus

Anterior cruciate ligament Tibia R Medial collateral ligament

L

Anterior meniscofemoral ligament Lateral collateral ligament

Medial meniscus

Posterior horn of lateral meniscus

Posterior horn of medial meniscus P Posterior cruciate ligament

695

Fibula Posterior meniscofemoral ligament

FIG. 10.73  Superior view of right knee with menisci and ligaments.

CHAPTER 10  Lower Extremity

696

IT band

Lateral femoral condyle

S

Femur

Posterior cruciate ligament

Medial femoral condyle

Medial collateral ligament

Anterior cruciate ligament L

R Lateral meniscus

Medial meniscus Medial intercondylar tubercle

Peroneus fibularis muscle Tibia Extensor digitorum longus muscle Tibialis anterior muscle

I

FIG. 10.74  Coronal, T1-weighted MRI of right knee with meniscus and ligaments. Biceps femoris muscle

S

Gastrocnemius muscle (medial head) Sartorius muscle

Lateral femoral condyle

Medial femoral condyle

Posterior meniscofemoral ligament

Posterior cruciate ligament

Lateral meniscus

Medial meniscus R

L Semimembranosus tendon

Lateral collateral ligament Fibula Popliteus muscle

Intercondylar eminence Medial gastrocnemius muscle

I

FIG. 10.75  Coronal, T1-weighted MRI of right knee with posterior meniscofemoral ligament.

CHAPTER 10  Lower Extremity S

Femur Quadriceps femoris tendon

Gastrocnemius muscle (lateral head) A

P Arcuate popliteal ligament

Fibula

Lateral meniscus (anterior horn)

Tibia

I

Lateral meniscus (posterior horn)

FIG. 10.76  Sagittal, T1-weighted MRI of knee with lateral meniscus and arcuate ligament.

S Semimembranosus muscle Vastus medialis muscle

Gastrocnemius muscle (medial head)

A

P Oblique popliteal ligament and posterior joint capsule

Femur

Medial meniscus (anterior horn)

Medial meniscus (posterior horn)

Medial patellar retinaculum

Popliteus muscle Tibia

I

FIG. 10.77  Sagittal, T1-weighted MRI of knee with medial meniscus and retinaculum.

697

698

CHAPTER 10  Lower Extremity Lateral patellar retinaculum

Patellar ligament

A

Medial meniscus (anterior horn)

Medial patellar retinaculum

Anterior cruciate ligament Medial tibial plateau

Lateral meniscus (anterior horn)

Medial collateral ligament

Posterior meniscofemoral ligament R

L Medial meniscus (posterior horn)

Lateral collateral ligament Biceps femoris tendon

Sartorius muscle Semimembranosus tendon

Oblique popliteal ligament

Gracilis tendon Popliteal artery

Popliteal vein

P

Posterior Semitendinosus tendon cruciate ligament

FIG. 10.78  Axial, T1-weighted MRI of right knee with menisci.

Lateral patellar retinaculum

Patellar ligament

A

Transverse ligament

Medial patellar retinaculum

Medial meniscus

Anterior cruciate ligament IT band

Medial collateral ligament

Lateral meniscus

Posterior cruciate ligament

Lateral collateral ligament R

L Gracilis tendon

Biceps femoris muscle and tendon

Sartorius muscle Semimembranosus tendon

Arcuate popliteal ligament

Semitendinosus tendon

Plantaris muscle Gastrocnemius Oblique popliteal muscle (lateral head) ligament

P

Gastrocnemius muscle (medial head)

FIG. 10.79  Axial, T1-weighted MRI of right knee with transverse ligament.

CHAPTER 10  Lower Extremity

Ligaments.  The ligaments of the knee are divided

699

joint capsule. The internal ligaments are found within the joint capsule and serve to provide stability to the tibia and femur. Ligaments of the knee are identified in Figs. 10.80–10.98.

into external (extracapsular) and internal (intracapsular) ligaments. The external ligaments are arranged around the knee and serve to strengthen and support the S

Femur Vastus intermedius tendon

Vastus medialis muscle Vastus lateralis muscle Quadriceps femoris tendon Iliotibial (IT) band

Medial epicondyle of femur Medial collateral ligament

L

Patella R

Medial patellar retinaculum

Lateral patellar retinaculum Semitendinosus tendon (cut)

Lateral collateral ligament

Gracilis tendon (cut) Biceps femoris tendon (cut)

Pes anserinus

Sartorius tendon (cut)

Patellar ligament Tibial tuberosity Fibula

Tibia

A I S

Femur

Plantaris muscle Lateral femoral condyle

Gastrocnemius muscle (medial head) Posterior meniscofemoral ligament

Gastrocnemius muscle (lateral head)

Medial femoral condyle

Lateral collateral ligament

R

L Lateral meniscus

Medial collateral ligament Medial meniscus Posterior cruciate ligament

Popliteus tendon

Semitendinosus tendon (cut) Popliteofibular ligament Popliteus muscle

B

Fibula

Tibia I

FIG. 10.80  (A) Anterior view of right knee with retinaculum and ligaments. (B) Posterior view of left knee with joint capsule and ligaments.

700

CHAPTER 10  Lower Extremity

External Ligaments.  The external ligaments of the knee include the collateral, patellar, patellar retinaculum, oblique popliteal, and arcuate popliteal ligaments (Figs. 10.80 and 10.81). The collateral ligaments provide support for the knee by reinforcing the joint capsule on the medial and lateral sides (Figs. 10.72–10.75, 10.78, and 10.79). The medial (tibial) collateral ligament is a flattened triangular ligament that originates from the medial femoral epicondyle and extends to the medial tibial condyle, continuing to the medial shaft of the tibia. Along its path, it fuses with the medial meniscus. The shorter, lateral (fibular) collateral ligament is more of a rounded cord arising from the lateral femoral epicondyle and attaching to the head of the fibula. The anterior joint capsule is strengthened by the patellar ligament and patellar retinaculum. The patellar ligament is the strong, thick band representing the continuation of the quadriceps tendon and extends from the patella to the tibial tuberosity (Figs. 10.80A, 10.87, 10.88, 10.94–10.96, and 10.98). The patellar retinaculum is formed mainly by fibrous extensions and fascia of various muscles about the knee (Figs. 10.79 and 10.80A). The medial patellar retinaculum is formed mainly by fibers from the vastus medialis muscle and runs distally to attach to the tibia just anterior to the medial collateral ligament. The lateral patellar retinaculum consists of fibers from the vastus lateralis muscle, as well as the iliotibial band, and attaches distally to the lateral margin of the tibial tuberosity to increase stability of the lateral joint capsule (Figs. 10.80A and 10.93–10.95). The

oblique and arcuate popliteal ligaments help reinforce the dorsal surface of the joint capsule. The oblique popliteal ligament is an expansion of the semimembranosus tendon that reinforces the central region of the posterior joint capsule. It extends laterally to attach to the intercondylar line of the femur (Figs. 10.77, 10.79, 10.81, 10.90, 10.95, and 10.98). The inferolateral portion of the posterior capsule is strengthened by the arcuate popliteal ligament as it passes superiorly from the apex of the fibular head to spread out over the posterior capsule with fibers continuing to the posterior intercondylar area and to the posterior surface of the lateral femoral condyle (Figs. 10.76, 10.81, 10.82, and 10.87).

Internal Ligaments.  The cruciate (cross-shaped) liga-

ments are strong bands of fibers that provide anterior and posterior stability to the knee. They are located within the joint capsule but outside the synovial membrane (Figs. 10.71–10.73). The anterior cruciate ligament arises from the medial intercondylar tubercle and extends to attach to the posteromedial surface of the lateral femoral condyle (Figs. 10.83, 10.84, 10.88, 10.94, 10.95, and 10.97). It helps prevent hyperextension and anterior displacement of the tibia. The posterior cruciate ligament is the stronger of the two and extends from the posterior aspect of the intercondylar eminence to the anteromedial surface of the medial femoral condyle. It functions to prevent hyperflexion and posterior displacement of the tibia (Figs. 10.83, 10.84, 10.88, 10.89, 10.95, and 10.97).

S

Posterior capsule

Gastrocnemius muscle (medial head)

Oblique popliteal ligament

Posterior oblique ligament

Popliteus tendon in hiatus Bursa deep to lateral collateral ligament

A

P

Lateral branch arcuate popliteal ligament

Posterior oblique component of medial collateral ligament Anterior branch semimembranosus tendon Semimembranosus slip to medial collateral ligament

Arcuate popliteal ligament fibular origin

Popliteus muscle

Proximal tibiofibular ligament

Semimembranosus muscle (cut and reflected distally)

I

FIG. 10.81  Posterior oblique view of left knee with ligaments.

CHAPTER 10  Lower Extremity

Biceps femoris muscle

Gastrocnemius muscle (lateral head)

S

Gastrocnemius muscle (medial head)

Lateral femoral condyle

Medial femoral condyle

Arcuate popliteal ligament

Medial meniscus (posterior horn)

Popliteofibular ligament R

L Tibia

Biceps femoris tendon Popliteus tendon and muscle Fibula

I

FIG. 10.82  Coronal, T1-weighted MRI of right knee with arcuate popliteal ligament. S Gastrocnemius muscle (lateral head)

Gastrocnemius muscle (medial head)

Lateral femoral condyle

Posterior cruciate ligament

Anterior cruciate ligament

Medial collateral ligament

Lateral meniscus

Medial meniscus R

L

Lateral collateral ligament

Medial tibial plateau

Lateral intercondylar tubercle Tibia

Fibula

I

FIG. 10.83  Coronal, T1-weighted MRI of right knee with menisci.

701

CHAPTER 10  Lower Extremity

702

S Vastus medialis muscle Gastrocnemius muscle (medial head)

Anterior cruciate ligament Lateral femoral condyle

Medial femoral condyle

Lateral collateral ligament

Posterior cruciate ligament

Lateral meniscus

Medial collateral ligament R

L Medial meniscus Medial intercondylar tubercle

Extensor digitorum longus muscle Peroneus longus muscle

Tibia

Tibialis anterior muscle

I

FIG. 10.84  Coronal, T1-weighted MRI of right knee with collateral ligaments.

S Vastus lateralis muscle

Vastus medialis muscle

Femur

IT band R

L Medial meniscus

Gerdy tubercle

Tibia

I

FIG. 10.85  Coronal, T1-weighted MRI of right knee with IT band.

CHAPTER 10  Lower Extremity S Vastus lateralis muscle

Biceps femoris muscle Gastrocnemius (lateral head) Lateral collateral ligament A

P Popliteus tendon

Lateral meniscus

Biceps femoris tendon (long head)

Tibia

Fibula Peroneus longus muscle

Tibialis anterior muscle

I

Tibialis posterior muscle

FIG. 10.86  Sagittal, T1-weighted MRI of knee with biceps femoris tendon.

S Biceps femoris muscle

Quadriceps femoris tendon

Plantaris muscle

Patella

Arcuate popliteal ligament

Articular cartilage Femur A

P

Patellar ligament

Lateral meniscus (posterior horn) Popliteus tendon

Infrapatellar fat pad Lateral meniscus (anterior horn)

Popliteofibular ligament Gastrocnemius muscle (lateral head)

Tibia Tibialis anterior muscle

I Tibialis posterior Fibula muscle

FIG. 10.87  Sagittal, T1-weighted MRI of knee with lateral meniscus.

703

CHAPTER 10  Lower Extremity

704

S

Popliteal vein Femur Popliteal artery Patella

Posterior meniscofemoral ligament

Patellar ligament A

P Posterior cruciate ligament

Infrapatellar fat pad

Gastrocnemius muscle (lateral head)

Anterior cruciate ligament

Popliteus muscle Tibial nerve

Tibia

Soleus muscle

Plantaris muscle I

FIG. 10.88  Sagittal, T1-weighted MRI of knee with anterior cruciate ligament.

S Semimembranosus muscle Vastus medialis muscle

Posterior joint capsule Posterior cruciate ligament

Femur

A

P

Meniscofemoral ligament

Medial meniscus (anterior horn)

Medial meniscus (posterior horn)

Tibia

Gastrocnemius muscle (medial head) Plantaris muscle Popliteus muscle I

FIG. 10.89  Sagittal, T1-weighted MRI of knee with posterior cruciate ligament.

CHAPTER 10  Lower Extremity Vastus medialis muscle

Femur

S

Semimembranosus muscle

Gastrocnemius muscle (medial head) Oblique popliteal ligament

Medial retinaculum A

P

Medial meniscus (anterior horn)

Medial meniscus (posterior horn)

Tibia

Popliteus muscle

I

FIG. 10.90  Sagittal, T1-weighted MRI of knee with medial meniscus.

Vastus medialis muscle

S

Posterior joint capsule

Semitendinosus tendon Semimembranosus tendon

Femur A

P

Medial meniscus

Tibia

Sartorius tendon

Gastrocnemius muscle (medial head)

Gracilis tendon Semitendinosus tendon I

FIG. 10.91  Sagittal, T1-weighted MRI of knee with semimembranosus tendon.

705

706

CHAPTER 10  Lower Extremity Quadriceps femoris tendon

A

Patella (base)

Vastus medialis muscle

Femur Vastus lateralis muscle

Adductor magnus tendon

IT band L

R

Sartorius muscle

Biceps femoris muscle (short head)

Gracilis muscle and tendon

Biceps femoris muscle (long head)

Semimembranosus muscle

Popliteal vein

Popliteal artery

P

Semitendinosus muscle

FIG. 10.92  Axial, T1-weighted MRI of right knee with quadriceps tendon.

Articular cartilage (patella)

Quadriceps femoris tendon

A

Patella

Patellofemoral joint

Lateral patellar retinaculum

Medial patellar retinaculum

Vastus lateralis tendon

Femur

IT band

Adductor magnus tendon L

R

Sartorius muscle

Biceps femoris muscle

Popliteal artery

Common peroneal nerve

Gracilis tendon Semimembranosus muscle and tendon

Plantaris muscle

Semitendinosus tendon Gastrocnemius muscle (lateral head)

Tibial nerve

P

Gastrocnemius muscle (medial head)

Popliteal vein

FIG. 10.93  Axial, T1-weighted MRI of right knee with patellofemoral joint.

CHAPTER 10  Lower Extremity Lateral Anterior patellar cruciate retinaculum ligament

Patellar ligament

Medial patellar retinaculum

A

Femur Medial femoral condyle

IT band Lateral femoral condyle

Medial collateral ligament

Lateral collateral ligament

Sartorius muscle L

R Popliteus tendon

Posterior joint capsule

Biceps femoris muscle

Gracilis tendon

Plantaris muscle

Semimembranosus muscle and tendon

Gastrocnemius muscle (lateral head)

Popliteal artery Popliteal vein

Tibial nerve

P

Gastrocnemius muscle (medial head)

Semitendinosus tendon

FIG. 10.94  Axial, T1-weighted MRI of right knee with patellar ligament.

Lateral Patellar patellar retinaculum ligament

A

Infrapatellar fat pad

Medial patellar retinaculum

Anterior cruciate ligament

Transverse ligament

Medial femoral condyle

IT band

Medial meniscus

Lateral femoral condyle

Medial collateral ligament

Lateral meniscus L

R

Sartorius muscle Posterior cruciate ligament

Lateral collateral ligament Biceps femoris muscle and tendon

Gracilis tendon

Oblique popliteal ligament

Semimembranosus tendon

Plantaris muscle

Semitendinosus tendon Popliteal vein

Gastrocnemius muscle (lateral head)

P

Tibial nerve

Popliteal artery

Gastrocnemius muscle (medial head)

FIG. 10.95  Axial, T1-weighted MRI of right knee with posterior cruciate ligament.

707

708

CHAPTER 10  Lower Extremity

IT band

Patellar ligament

Tibia

A

Gerdy tubercle Lateral collateral ligament

Medial collateral ligament

Biceps femoris tendon

Gracilis tendon L

R Arcuate popliteal ligament

Sartorius muscle

Popliteus muscle

Semimembranosus tendon

Plantaris muscle

Semitendinosus tendon

Popliteal vein Popliteal artery

Gastrocnemius muscle (lateral head)

P

Tibial nerve

Gastrocnemius muscle (medial head)

FIG. 10.96  Axial, T1-weighted MRI of right knee with popliteus muscle.

A

Patella

Posterior cruciate ligament

Iliotibial (IT) band

Medial condyle

Anterior cruciate ligament

Medial collateral ligament R

L

Lateral condyle Sartorius muscle

Popliteus tendon

Popliteal artery

Biceps femoris muscle

Plantaris muscle

Gastrocnemius muscle (lateral head) P

FIG. 10.97  Axial CT scan of right knee with cruciate and collateral ligaments.

CHAPTER 10  Lower Extremity Patellar ligament

A

709

Infrapatellar fat pad Medial meniscus, anterior horn

Iliotibial (IT) band

Medial femoral condyle

Posterior cruciate ligament

R

L Sartorius muscle

Biceps femoris muscle

Oblique popliteal ligament and joint capsule

Gastrocnemius muscle (lateral head)

Gastrocnemius muscle (medial head)

Plantaris muscle

Popliteal vein

P

Popliteal artery

FIG. 10.98  Axial, CT scan of right knee.

Tendons The tendons of the sartorius, gracilis, and semitendinosus muscles merge to form a conjoined tendon commonly referred to as the pes anserinus. It inserts onto the anteromedial surface of the proximal tibia just superficial to the medial collateral ligament (Figs. 10.64, 10.80A, and 10.91–10.96).

Bursae There are more than 10 bursae located around the knee joint because of the number of muscles associated with the knee. The major bursae include the suprapatellar, prepatellar, infrapatellar (superficial and deep), gastrocnemius (medial and lateral), semimembranosus, and popliteal bursae (Fig. 10.99). The suprapatellar (quadriceps) bursa is a large extension of the synovial capsule located between the femur and the quadriceps tendon. The prepatellar bursa lies between the anterior surface of the patella and the skin, whereas the superficial infrapatellar bursa lies over the patellar ligament between the skin and the tibial tuberosity. The deep infrapatellar bursa is a small bursa located beneath the patellar ligament and anterior to the tibia just above the tibial tube­ rosity. Behind each femoral condyle is usually a bursa for the respective head of the gastrocnemius muscle.

The gastrocnemius bursae are located between each muscle head and the joint capsule. The semimembranosus bursa is located between the medial head of the gastrocnemius and semimembranosus tendon, and the small popliteal bursa lies between the lateral tibial condyle and the popliteus tendon. There exists a small bursa adjacent to the tendons of the pes anserinus on the anteromedial surface of the knee called the pes anserinus bursa. Bursae are difficult to see in cross-section images unless they are abnormal.

Muscles of the Lower Leg With the exception of the popliteus, all muscles arising from the lower leg are attached to bones of the foot. The muscles of the lower leg can be classified according to their location. They are divided into anterior and posterior groups by the tibia, fibula, and interosseous membrane. The two main groups are divided again into subgroups or layers. These muscles are shown in Figs. 10.100–10.116 and described in Table 10.3.

Anterior Group.  The anterior muscle group can be subdivided into the extensor group located anteriorly and the peroneus group located laterally.

CHAPTER 10  Lower Extremity

710

Gastrocnemius muscle (medial head) S

S

Femur

Quadriceps femoris muscle

Femur

Gastrocnemius muscle (lateral head)

Suprapatellar bursa

Lateral collateral ligament

Gastrocnemius bursa

Quadriceps femoris tendon

Synovial capsule of knee joint

Prepatellar bursa

P

A Patella

Popliteus muscle and tendon

Patellar ligament Deep infrapatellar bursa

Fibula

Superficial infrapatellar bursa

Tibia

Semimembranosus tendon Semimembranosus bursa

R

L

Posterior meniscofemoral ligament Lateral collateral ligament

Pes anserinus bursa

Popliteus tendon Popliteal bursa Posterior cruciate ligament

Popliteus muscle (cut)

I

I Tibia

Fibula

FIG. 10.99  Knee bursae. Left, Lateral view. Right, Posterior view.

S

S

Head of fibula

Peroneus (fibularis) longus muscle Gastrocnemius muscle

Tibialis anterior muscle

Gastrocnemius muscle

L

Extensor digitorum longus muscle

A P

Soleus muscle

Peroneus (fibularis) longus muscle

Extensor hallucis longus muscle

Peroneus tertius muscle

Extensor digitorum longus muscle

Soleus muscle

Tibia

R

Patella

Tibialis anterior muscle Extensor hallucis longus muscle

Peroneus (fibularis) brevis muscle

Peroneus tertius muscle

Flexor hallucis longus muscle

Superior and inferior extensor retinacula

Superior and inferior extensor retinacula

Lateral malleolus Fibular retinaculum Achilles tendon

Extensor hallucis brevis muscle

I Extensor digitorum brevis muscle

I

FIG. 10.100  Anterior view of muscles and retinacula of right lower leg.

Fifth metatarsal

FIG. 10.101  Lateral view of superficial muscles of the right lower leg.

CHAPTER 10  Lower Extremity Patellar ligament

Anterior cruciate ligament

Infrapatellar fat Transverse ligament

A

Medial meniscus

Iliotibial (IT) band Lateral meniscus

Medial collateral ligament Anterior meniscofemoral ligament

711

Lateral collateral ligament R

L

Posterior meniscofemoral ligament

Biceps femoris muscle Peroneal nerve

Sartorius muscle

Popliteus tendon

Posterior cruciate ligament

Plantaris muscle P

Gracilis tendon

Gastrocnemius muscle, (lateral head)

Semimembranosus muscle Gastrocnemius muscle, (medial head)

Semitendinosus muscle

FIG. 10.102  Axial view of knee with femoral condyles.

A

Semimembranosus tendon

Tibialis anterior muscle

Tibia

Interosseous membrane Extensor digitorum longus muscle

Sartorius tendon

Anterior tibial artery and vein

Gracilis tendon Great saphenous vein Popliteus muscle

Peroneus longus muscle L

R

Fibula Common peroneal (fibular) nerve

Saphenous nerve

Soleus muscle

Popliteal vein Tibial nerve

Lateral sural cutaneous nerve

Popliteal artery Gastrocnemius muscle (medial head)

Gastrocnemius muscle (lateral head)

P

Small saphenous vein

Plantaris muscle

FIG. 10.103  Axial view proximal portion of left lower leg. Anterior Group—Extensor Group  Tibialis anterior Extensor digitorum longus Extensor hallucis longus Peroneus tertius The tibialis anterior muscle is a long, spindle-shaped muscle located just lateral to the anterior surface of the tibia. It arises from the upper two-thirds of the lateral

surface of the tibia and adjoining interosseous membrane, becoming tendinous over the lower third. The tibialis anterior muscle runs distally and medially over the tibia to insert on the plantar surface of the medial cuneiform and first metatarsal. Its actions include dorsiflexion of the foot at the ankle joint, and together with the tibialis posterior muscle, it inverts the foot (Figs. 10.100–10.109). The extensor digitorum longus muscle is located lateral to the tibialis anterior muscle in the anterior aspect

712

CHAPTER 10  Lower Extremity

Tibia

Tibialis anterior muscle A Interosseous membrane Anterior tibial artery and vein

Tibialis posterior muscle

Extensor digitorum longus muscle

Flexor digitorum longus muscle

Extensor hallucis longus muscle Deep peroneal (fibular) nerve

Posterior tibial artery and veins Tibial nerve

Peroneus brevis muscle L

R

Peroneus longus muscle Fibula

Great saphenous vein

Peroneal fibular artery and nerve

Saphenous nerve

Flexor hallucis longus muscle

Plantaris tendon

Sural nerve Small saphenous vein

P Gastrocnemius muscle

Soleus muscle

FIG. 10.104  Axial view middle portion of left lower leg.

Tibialis anterior tendon Tibia

A

Anterior tibial artery and veins

Great saphenous vein

Superficial peroneal (fibular) nerve Deep peroneal (fibular) nerve

Saphenous nerve

Extensor hallucis longus muscle

R

L

Tibialis posterior tendon

Extensor digitorum longus muscle Interosseous membrane Fibula Peroneus longus muscle

Flexor digitorum longus muscle

Peroneus brevis muscle Small saphenous vein

Posterior tibial artery and veins

Sural nerve Flexor hallucis longus muscle

Tibial nerve P

Achilles tendon

FIG. 10.105  Axial view distal portion of left lower leg.

of the leg. It arises from the upper two-thirds of the fibula and adjoining interosseous membrane and the lateral condyle of the tibia. The tendon of the extensor digitorum longus muscle passes over the front of the ankle joint and gives rise to four separate tendons at the level of the inferior extensor retinaculum that run to the dorsal surface of the second through fifth digits. The extensor digitorum longus muscle is an extensor of the lateral four digits at the metatarsophalangeal joints (Figs. 10.100, 10.101, 10.103–10.109, and 10.112).

The extensor hallucis longus muscle lies posterior to and between the tibialis anterior and extensor digitorum longus muscles. It arises from the middle half of the anterior fibula and interosseous membrane. The tendon of the extensor hallucis longus muscle passes through the inferior extensor retinaculum to the base of the great toe and inserts into the distal phalanx. The extensor hallucis longus muscle extends the joints of the great toe and provides dorsiflexion of the foot at the ankle joint (Figs. 10.100, 10.101, 10.104–10.109, and 10.112).

CHAPTER 10  Lower Extremity Gracilis tendon

Sartorius tendon

Tibia

Tibial tuberosity

A

Patellar ligament Tibialis anterior muscle Extensor digitorum longus muscle

Semitendinosus tendon Popliteus muscle

L

R

Peroneus longus muscle Fibula

Popliteal vein

Common peroneal nerve

Popliteal artery

Soleus muscle

Gastrocnemius muscle (medial head)

P

Plantaris muscle

Tibial nerve

Gastrocnemius muscle (lateral head)

FIG. 10.106  Axial, T1-weighted MRI of left tibia.

Popliteus muscle

Tibialis posterior muscle

A

Tibia

Tibialis anterior muscle

Anterior tibial artery and vein Extensor digitorum longus muscle Fibula Gastrocnemius muscle (medial head)

L

R

Peroneus brevis muscle

Posterior tibial vein

Peroneus longus muscle

Posterior tibial artery Soleus muscle Plantaris tendon

Gastrocnemius muscle (lateral head)

P

Tibial nerve

FIG. 10.107  Axial, T1-weighted MRI of left tibia.

713

714

CHAPTER 10  Lower Extremity Flexor digitorum longus muscle

Tibialis posterior muscle

Tibia

A

Tibialis anterior muscle

Tibial nerve Posterior tibial vein Posterior tibial artery

L

R

Extensor digitorum longus muscle Extensor hallucis longus muscle Peroneal nerve Peroneus brevis muscle Peroneus longus muscle

Gastrocnemius muscle (medial head)

Fibula

Soleus muscle

Plantaris tendon

Flexor hallucis longus muscle

P

Peroneal Gastrocnemius vessels muscle (lateral head)

FIG. 10.108  Axial, T1-weighted MRI of left tibia.

Tibia

A

Tibialis anterior tendon Extensor hallucis longus muscle

Tibialis posterior muscle

Extensor digitorum longus muscle

Flexor digitorum longus tendon

Peroneus brevis muscle

Posterior tibial vein R

L Fibula

Posterior tibial artery

Peroneus longus muscle

Tibial nerve

Flexor hallucis longus muscle

Plantaris tendon Soleus muscle Achilles tendon P

FIG. 10.109  Axial, T1-weighted MRI of left tibia.

CHAPTER 10  Lower Extremity Tibia

715

S

S

Popliteus muscle

Fibula

Gastrocnemius muscle (medial head) Peroneus longus muscle

Soleus muscle

Peroneus brevis muscle

Peroneus longus muscle

Soleus muscle R

L

R

Gastrocnemius muscle (medial head)

L

Flexor hallucis longus muscle

I

I

FIG. 10.110  Coronal, T1-weighted MRI of left fibula.

FIG. 10.111  Coronal, T1-weighted MRI of left lower leg.

The peroneus tertius muscle is considered by some to be a distal extension of the extensor digitorum longus muscle. It arises from the anterior surface of the lower fibula, and its tendon inserts on the dorsal aspect of the base of the fifth metatarsal. This muscle functions as a weak evertor and dorsiflexor of the foot at the ankle joint (Figs. 10.100 and 10.101).

longer tendon. The tendon of the peroneus longus muscle runs in a shallow groove behind the lateral malleolus, passing below the peroneal tubercle of the calcaneus and across the lateral side of the cuboid. It then runs obliquely across the sole of the foot to insert on the base of the first metatarsal and lateral surface of the medial cuneiform (Figs. 10.100, 10.101, 10.103–10.111, and 10.114–10.116). The peroneus (fibularis) brevis muscle is shorter and smaller than its counterpart. It lies under the peroneus longus, arising from the distal two-thirds of the lateral surface of the fibula. The tendon of the peroneus brevis muscle accompanies the tendon of the peroneus longus muscle in a common synovial sheath behind the lateral malleolus, with the peroneus brevis just anterior to the peroneus longus. At approximately the level of the peroneal tubercle of the calcaneus, the tendons separate into their own synovial sheath, with the peroneus brevis tendon attaching to the base of the fifth metatarsal (Figs. 10.100, 10.101, 10.104, 10.105, 10.107–10.110, and 10.114–10.116).

Anterior Group–Peroneus Group  Peroneus (fibularis) longus Peroneus (fibularis) brevis The two peroneus muscles act as plantar flexors but also stabilize the lateral ankle and longitudinal arch of the foot (Figs. 10.100 and 10.101). The peroneus (fibularis) longus muscle is located on the lateral side of the leg arising from the tibiofibular joint, the head of the fibula, and the lateral condyle of the tibia. The peroneus longus muscle has a long belly and an even

716

CHAPTER 10  Lower Extremity S Gastrocnemius muscle (lateral head)

Patellar ligament

Head of fibula

Tibia Popliteus muscle

Fibula Soleus muscle

Tibialis posterior muscle A

P

Extensor hallucis longus muscle

Extensor digitorum longus muscle

I

FIG. 10.112  Sagittal, T1-weighted MRI of fibula.

Posterior Group.  The posterior group is functionally

considered the flexors, which are responsible for plantar flexion of the foot. This group is subdivided into the superficial layer and the deep layer. These muscles are shown in Figs. 10.101–10.116 and described in Table 10.3. Posterior Group–Superficial Layer  Gastrocnemius Soleus Plantaris The gastrocnemius muscle is a prominent flexor of the foot and is responsible for giving the calf its shape on the back of the leg. It consists of two heads arising from the medial and lateral femoral condyles. The medial head arises from the medial supracondylar ridge and adductor tubercle on the popliteal surface of the femur. The lateral head arises just behind the lateral epicondyle on the outer surface of the lateral femoral condyle. The two heads form the lower boundaries of the popliteal fossa, and their fibers run distally, where they join the tendon of the soleus muscle to form the Achilles tendon, which inserts on the calcaneal tuberosity (Figs. 10.28 and 10.101–10.116). The soleus muscle is a broad, flat muscle located beneath the gastrocnemius. It arises from the soleal line on

the posterior tibia and the upper third of the fibula. The muscle fibers run distally and merge with the tendon of the gastrocnemius to form the superficial Achilles tendon (Figs. 10.101, 10.103, 10.104, and 10.106–10.116). The plantaris muscle is a long, thin muscle that arises from the lowest part of the lateral supracondylar ridge, the adjacent popliteal surface, and the joint capsule. The tendon runs inferiorly between the gastrocnemius and soleus muscles, following the medial edge of the Achilles tendon to insert on the Achilles tendon or calcaneus (Figs. 10.102–10.104, 10.106, and 10.114–10.116). Posterior Group–Deep Layer  Tibialis posterior Flexor hallucis longus Flexor digitorum longus Popliteus The tibialis posterior muscle is the deepest muscle located on the back of the leg. It arises from the superolateral surface of the posterior tibia just below the soleal line, the interosseous membrane, and the posterior surface of the fibula. The tendon of the tibialis posterior muscle passes through the malleolar groove of the tibia behind the medial malleolus to attach to the tuberosity

CHAPTER 10  Lower Extremity

717

S Posterior cruciate ligament

Patellar ligament

Popliteus muscle

Tibia

Gastrocnemius muscle (medial head)

Flexor digitorum longus muscle

A

P

Flexor hallucis longus muscle

Soleus muscle

FIG. 10.113  Sagittal, T1-weighted

MRI of tibia.

I S Vastus lateralis tendon Biceps femoris tendon

Semimembranosus muscle and tendon

Plantaris muscle

Sartorius tendon Semitendinosus tendon

Medial head Lateral head

Gastrocnemius muscle

Soleus muscle Peroneus longus muscle Gastrocnemius tendon Peroneus brevis muscle Achilles (calcaneal) tendon Medial malleolus

Lateral malleolus Calcaneus I

FIG. 10.114  Posterior view of superficial muscles of leg.

of the navicular and plantar surface of the medial cuneiform bones (Figs. 10.104, 10.105, 10.107–10.109, 10.112, and 10.116). The flexor hallucis longus muscle is a powerful muscle located beneath the gastrocnemius and soleus muscles. It arises from the distal two-thirds of the posterior fibula, the interosseous membrane, and adjacent fascia. The tendon of the flexor hallucis longus muscle runs distally, crossing over the dorsal aspect of the ankle, through the malleolar groove of the tibia to the sole of the foot, where it inserts into the base of the distal phalanx of the first toe (Figs. 10.104, 10.105, 10.108– 10.110, and 10.113). The flexor digitorum longus muscle arises from the posterior surface of the body of the tibia immediately below the soleal line. The muscle descends along the tibial side of the leg to become tendinous just above the medial malleolus. The tendon of the flexor digitorum longus muscle passes behind the medial malleolus to the sole of the foot, deep to the flexor hallucis longus, and divides into four individual tendons that insert into the bases of the distal phalanges of the second through fifth digits (Figs. 10.104, 10.105, 10.108, 10.109, 10.113, and 10.116). The popliteus muscle is a thin triangular muscle that forms the lower floor of the popliteal fossa. It arises just below the lateral femoral epicondyle and extends obliquely to the triangular surface above the soleal (popliteal) line on the posterior tibia (Figs. 10.103, 10.106, 10.107, 10.110, 10.112, 10.113, 10.115, and 10.116).

CHAPTER 10  Lower Extremity

718

S

S

Biceps femoris tendon

Plantaris muscle (cut)

Plantaris muscle

Semimembranosus muscle and tendon

Medial head Lateral head

Sartorius tendon Popliteus muscle Semitendinosus tendon

Gastrocnemius muscle (cut)

Medial head Gastrocnemius Lateral muscle (cut) head

Popliteus muscle

Soleus muscle (cut)

Head of fibula Soleus muscle

Fibula

Tibialis posterior muscle

Plantaris tendon

Peroneus longus muscle

Flexor digitorum longus muscle

Flexor hallucis longus muscle

Peroneus longus muscle

Peroneus brevis muscle Achilles (calcaneal) tendon

Tibialis posterior tendon

Peroneus brevis muscle

Tibialis posterior tendon Medial malleolus Achilles tendon (cut)

Calcaneus

I

FIG. 10.116  Posterior view of deep muscles of leg.

I

FIG. 10.115  Posterior view of soleus muscle. TABLE 10.3

Muscles of the Lower Leg

Muscle

Proximal Insertion

Distal Insertion

Action

Anterior Group Extensor Group Tibialis anterior

Lateral tibia, upper two-thirds

Medial cuneiform and first metatarsal, plantar surface Second to fifth digits of foot

Dorsiflexion of foot

Extensor digitorum longus Extensor hallucis longus Peroneus tertius Peroneus Group Peroneus longus

Proximal fibula and interosseous membrane Anterior fibula and interosseous membrane Distal fibula Tibiofibular joint, head of fibula, and lateral condyle of tibia Lateral surface of distal fibula

Peroneus brevis Posterior Group Superficial Layer Gastrocnemius Medial head: supracondylar ridge and adductor tubercle Lateral head: lateral epicondyle of femur Soleus Soleal line of tibia and proximal fibula Plantaris Lateral supracondylar ridge Deep Layer Tibialis posterior Posterior tibia, interosseous membrane, and posterior fibula Flexor hallucis Posterior fibula, interosseous memlongus brane, and adjacent fascia Flexor digitorum Posterior body of tibia below soleal line longus Popliteus Lateral femoral epicondyle

Distal phalanx of first toe Base of fifth metatarsal

Extensor of lateral four digits at the metatarsophalangeal joints Extends joints of first toe and dorsiflexion of foot Evertor and dorsiflexion of the foot

First metatarsal and lateral surface of medial cuneiform Fifth metatarsal

Plantar flexion and stabilizer of ankle

Both heads join soleus tendon to form Achilles tendon to insert on calcaneal tuberosity Achilles tendon Medial side of Achilles tendon or calcaneus

Flexor of the foot

Navicular and plantar surface of medial cuneiform Distal phalanx of first toe

Flexor of the foot

Distal phalanges of second to fifth digits

Flexor of the foot

Posterior, proximal tibia

Flexor of the foot

Plantar flexion and stabilizer of ankle

Flexor of the foot Flexor of the foot

Flexor of the foot

CHAPTER 10  Lower Extremity

ANKLE AND FOOT Bony Anatomy

719

(trochlea) that is wider in front than in back (Figs. 10.117, 10.118, 10.121, and 10.122). The cartilage-covered trochlea provides articulation with the tibia and fibula (Figs. 10.121–10.128). The short, broad neck extends anteriorly to the head, which articulates with the navicular bone (Figs. 10.118 and 10.121). The largest tarsal bone is the calcaneus, which lies beneath the talus. It has an elongated cuboid shape with a posterior surface comprising the prominence of the heel. On the medial surface of the calcaneus is a shelflike process termed the sustentaculum tali, which provides support for the talus (Figs. 10.119, 10.120, and 10.124– 10.126). On the plantar surface of the posterior calcaneus is the large calcaneal tuberosity for insertion of

The bony anatomy of the ankle and foot includes the tarsals, metatarsals, and phalanges. The tarsals consist of seven bones: talus, calcaneus, navicular, cuboid, and three cuneiform bones. Five metatarsals and 14 phalanges make up the toes (Figs. 10.117–10.141).

Tarsals.  The talus (astragalus) is the second largest tarsal bone. Together with the calcaneus, it is responsible for transmitting the entire weight of the body to the foot. The talus consists of a body, neck, and head. The body is wedge-shaped with an upper articular surface

Head Body

Distal

Base

Middle

Head Body

Phalanges

Proximal 1

2

Intermetatarsal joints

3 4

Base

5

Medial cuneiform Intermediate cuneiform

Metatarsals

Talus

Facet for medial malleolus Navicular

Lateral cuneiform

Navicular

Intermediate cuneiform

Cuboid

Head of talus Neck of talus

Trochlea of talus

Talus

First metatarsal

Tarsals

Medial cuneiform First proximal phalanx

Calcaneus

A

Sustentaculum tali Calcaneus

First distal phalanx

B

Calcaneal tuberosity

Facet for lateral malleolus Talus

Navicular Intermediate cuneiform Lateral cuneiform Medial longitudinal arch

Cuboid

C

Calcaneus

Fifth metatarsal

D

Transverse arch

Lateral longitudinal arch

FIG. 10.117  Bones of the right foot. (A) Superior view. (B) Medial view. (C) Lateral view. (D) Arches of foot.

720

CHAPTER 10  Lower Extremity A

Distal phalanx

Distal interphalangeal joint

Middle phalanx

Proximal interphalangeal joint

Proximal phalanx

Metatarsophalangeal joint

5

4

3

First metatarsal

2

Intermetatarsal joint

Intermediate cuneiform

Tarsometatarsal joint Medial cuneiform

Lateral cuneiform

Navicular

Cuboid

Head of talus Neck of talus Body of talus

Calcaneus

A P

Medial cuneiform

Facet for medial Navicular malleolus S

Trochlea Talus

Sustentaculum tali A

P Calcaneus

Interphalangeal joint

Medial process of calcaneal tuberosity

First distal phalanx

B First proximal phalanx

I First Sesamoid metatarsal bones

Fifth metatarsal

Cuboid

FIG. 10.118  (A) 3D CT of foot, superior view. (B) 3D CT of foot, medial view.

  Continued

CHAPTER 10  Lower Extremity Facet for Talocalcaneonavicular lateral malleolus joint

S

Navicular

721

Intermediate cuneiform

Talus Lateral cuneiform

Subtalar joint P

A

Calcaneus Calcaneal tuberosity

4

3

2

Tarsometatarsal joint Interphalangeal joint Fifth distal phalanx

C Sinus tarsi

Cuboid Calcaneocuboid joint

I

Fifth middle Metatarsophalangeal phalanx joint Fifth Fifth proximal metatarsal phalanx

FIG. 10.118, cont’d  (C) 3D CT of foot, lateral view.

A

Anterior facet

Sustentaculum tali

Middle facet Peroneal tubercle

Medial process of calcaneal tuberosity P

Middle facet Anterior facet

Sustentaculum tali Posterior facet

Calcaneal tuberosity

Posterior facet

P

A

Calcaneal tuberosity

FIG. 10.119  Left calcaneus. Left, Dorsal aspect. Right, Medial aspect.

ligaments and tendons, the largest being the Achilles tendon (Figs. 10.119–10.123). The articulation between the talus and calcaneus is termed the subtalar joint, which is composed of three articulations formed by the anterior, middle, and posterior facets (Figs. 10.119 and 10.120). The smallest of the three is the anterior facet, which can be independent of or continuous with the middle facet. The middle facet lies on a ledge of bone projecting off the medial surface of the calcaneus at the sustentaculum tali (Figs. 10.119–10.122 and 10.124– 10.126). This shelf and the entire middle facet joint provide weight-bearing support to the medial side of the ankle. The posterior facet joint is the largest and provides

support for most of the body of the talus (Figs. 10.119– 10.123). Separating this facet from the middle facet is the tarsal canal. This canal contains blood vessels, fat, and the interosseous talocalcaneal ligament. The tarsal canal widens laterally to form the sinus tarsi, which contains the cervical ligament (Figs. 10.121–10.124, 10.139, and 10.140). In addition to the talus and calcaneus, the cuboid, navicular, and three cuneiform bones make up the remaining five tarsal bones of the foot (Figs. 10.117, 10.118, and 10.129–10.141). Lateral and anterior to the calcaneus is the cuboid bone, which articulates anteriorly with the bases of the fourth and fifth metatarsal

722

CHAPTER 10  Lower Extremity A

Anterior facet

Middle facet

Sustentaculum tali Calcaneal sulcus

Posterior facet

Calcaneal tuberosity

A P Anterior facet

A

Middle facet

Posterior facet

P Calcaneal tuberosity

B FIG. 10.120  (A) 3D CT of calcaneus, dorsal view. (B) 3D CT of calcaneus, lateral view.

CHAPTER 10  Lower Extremity

723

S Tibia Extensor hallucis longus muscle Talocrural (ankle) joint Neck of talus Flexor hallucis longus muscle

Anterior subtalar joint Head of talus Navicular Intermediate (second) cuneiform

Body of talus Posterior subtalar joint

Tarsometatarsal joint Tendon of fibularis longus muscle

Achilles tendon

Second metatarsal

P

Interosseous talocalcaneal ligament Calcaneus

A

Calcaneal tuberosity Subcalcaneal fat pad

I

Tarsal canal

Spring (plantar) ligament

Base of proximal phalanx Metatarsophalangeal joint

Plantar fascia

Adductor hallucis muscle, oblique head

Flexor digitorum brevis muscle Talocalcaneonavicular joint

First dorsal interosseous muscle

Quadratus plantae muscle

FIG. 10.121  Sagittal section of foot.

S

Tibia Extensor hallucis longus tendon

Talocrural (ankle) joint A

P

Extensor digitorum longus tendon

Body of talus

Neck of talus Posterior facet

Transverse (midtarsal) joint (dotted line) Talocalcaneonavicular joint

Sinus tarsi

Navicular

Calcaneal tuberosity

Head of talus Cuboid

Anterior Calcaneocuboid facet joint (dotted line)

I

Cervical ligament

FIG. 10.122  Sagittal, T1-weighted MR scan of calcaneus.

724

CHAPTER 10  Lower Extremity S Talocrural (ankle) joint

Tibia Posterior subtalar joint

Talocalcaneonavicular joint

A

P

Calcaneocuboid joint

Sinus tarsi

Calcaneus

Calcaneal tuberosity Cuboid Transverse (midtarsal) joint (dotted line) I

FIG. 10.123  Sagittal CT reformat of calcaneus.

S

Epiphysial line

Tibia

Talocrural (mortise) joint

Interosseous membrane

Medial malleolus of tibia

Body of talus

Deltoid ligament (posterior tibiotalar part)

Epiphysial line

Flexor retinaculum

Lateral malleolus of fibula

Tendon and sheath of tibialis posterior muscle

Posterior talofibular ligament

Tendon and sheath of flexor digitorum longus muscle

Calcaneofibular ligament

Tendon and sheath of flexor hallucis longus muscle

Superior peroneal retinaculum

Middle subtalar joint Tendon of peroneus brevis muscle

Interosseous talocalcaneal ligament

Tendon sheath of peroneal muscles

Sustentaculum tali

Tendon of peroneus longus muscle

Medial plantar vessels and nerve

Inferior peroneal retinaculum

Quadratus plantae muscle

Calcaneus

Abductor hallucis muscle

Abductor digiti minimi muscle

Lateral plantar vessels and nerve

Plantar fascia I

Flexor digitorum brevis muscle

FIG. 10.124  Coronal view of subtalar joint.

CHAPTER 10  Lower Extremity Talocrural (mortise) joint

S

725

Talus

Tibia

Deltoid ligament

Sustentaculum tali R

Talus L Middle subtalar joint

Abductor hallucis muscle Calcaneus

Flexor Quadratus digitorum plantae muscle brevis muscle

I

Plantar fascia

Abductor digiti minimi muscle

FIG. 10.125  Coronal, T1-weighted MRI of talocrural joint, left ankle.

Fibula

S

Talocrural joint (mortise) joint Tibia Talus Middle subtalar joint Sustentaculum tali

R

L Calcaneus

I

FIG. 10.126  Coronal CT reformat of subtalar joint, right ankle.

CHAPTER 10  Lower Extremity

726

bones. The navicular bone articulates posteriorly with the talus and anteriorly with the cuneiform bones on the medial side of the foot. The three cuneiform bones— medial, intermediate, and lateral—articulate anteriorly with the first three metatarsal bones (Figs. 10.117, 10.118, and 10.129–10.132).

Sinus Tarsi Syndrome Sinus tarsi syndrome is a common syndrome associated with posttraumatic lateral hindfoot pain. The interosseous ligament, when injured due to lateral ankle sprains or an inflammatory process, such as arthritis, can lead to characteristic pain over the lateral side of the ankle. Treatment may include anti-inflammatory medication, a period of immobilization, or injection of local anesthetic.

Medial Tibionavicular malleolus ligament A

Metatarsals.  The metatarsals are long, slender bones.

There are five metatarsals in each foot, with each bone having a distal head, proximal base, and body or shaft in between. The heads articulate with the proximal phalanges of the toes, and the bases articulate with the tarsals (Figs. 10.117, 10.118, 10.129–10.132, and 10.136– 10.141). The first metatarsal is associated with two sesamoid bones. They can be found on the medial and lateral surfaces of the metatarsal head and are embedded within the medial and lateral slips of the flexor hallucis brevis tendon.

Phalanges.  Each foot has 14 phalanges—3 phalanges

for each toe (proximal, middle, distal), except the great toe, which has just 2 (proximal and distal). The phalanges of the toes are shorter and stouter than their counterparts in the fingers and, like the metatarsals, have a base, body, and head (Figs. 10.117, 10.118, 10.131, 10.132, and 10.139).

Talus

Anterior talofibular ligament

Tibiotalar ligament R

A

L Medial malleolus of tibia

Flexor hallucis longus muscle and tendon

Talus

R

L Lateral malleolus of fibula

Soleus muscle

Achilles tendon

P

Posterior Lateral talofibular malleolus ligament

FIG. 10.127  Axial, T1-weighted MRI of left ankle.

P

FIG. 10.128  Axial CT of left ankle.

CHAPTER 10  Lower Extremity

Joints The joints of the ankle and foot include the talocrural (ankle); intertarsal, tarsometatarsal, and intermetatarsal; metatarsophalangeal; and interphalangeal joints. The joints of the ankle and foot are shown in Figs. 10.118 and 10.121–10.141.

Talocrural.  The talocrural joint (ankle joint) is cre-

ated by the articulations between the tibia, fibula, and talus. The tibia and fibula rest on the trochlear surface of the talus to form what is commonly termed the mortise joint, which allows for dorsal and plantar flexion. Both the tibia and fibula terminate distally in projections termed malleoli, which prevent medial and lateral displacement of the talus (Figs. 10.121– 10.128).

Intertarsal.  The intertarsal joints are created by the articulations between the tarsal bones and include the subtalar, talocalcaneonavicular, calcaneocuboid, transverse (midtarsal), cuneonavicular, intercuneiform, and the cuneocuboid joints. The subtalar joint consists of the articulation between the talus and calcaneus and was discussed under bony anatomy (Figs. 10.121– 10.123). The subtalar joint provides the ability to invert and evert the foot. The talocalcaneonavicular and calcaneocuboid joints combine to form the transverse or midtarsal joint. This joint provides an irregular plane across the foot extending from side to side, with the talus and calcaneus located posteriorly and the navicular and cuboid located anteriorly (Figs. 10.122 and 10.123). The transverse tarsal joint plays an important part in putting the spring in your step by acting as a shock absorber during the push-off phase of walking or running. The cuneonavicular, intercuneiform, and cuneocuboid joints contribute to the flexibility of the foot by providing a slight gliding movement between bones. Tarsometatarsal.  The tarsometatarsal joints exist

between the bases of all five metatarsals and the anterior four tarsal bones (cuboid, three cuneiforms). The articulations between the tarsals and metatarsals permit only limited gliding movement between the bones (Figs. 10.121 and 10.129–10.132). The intermetatarsal

727

joints are the articulations between the bases of the lateral four metatarsals. The intermetatarsal joints permit a small degree of gliding between metatarsals and contribute to eversion and inversion of the foot (Figs. 10.118A and 10.131).

Metatarsophalangeal.  The heads of the metatarsals

articulate with the bases of the proximal phalanges at the metatarsophalangeal joints (Figs. 10.118A, 10.121, 10.131, and 10.140). This articulation provides flexion and extension of the toes.

Interphalangeal.  The heads of the phalanges articulate with the bases of the more distal phalanges to create the interphalangeal joints. The interphalangeal joints are hinge joints that permit plantar and dorsiflexion of the phalanges (Fig. 10.118).

Arches The bones of the foot are arranged in transverse and longitudinal arches that provide flexibility and resilience to the foot to support the weight of the body, absorb shocks, and provide spring and lift during activity (Fig. 10.117). The longitudinal arch (plantar arch) has two parts: one on the lateral side of the foot (lateral longitudinal arch) and one on the medial side of the foot (medial longitudinal arch). The bony landmarks for the medial longitudinal arch are the head of the first metatarsal anteriorly and the calcaneal tuberosity posteriorly. On the lateral side the bony landmarks include the head of the fifth metatarsal anteriorly and the calcaneal tuberosity posteriorly. The medial longitudinal arch is more elastic and is associated with greater curvature, whereas the lateral longitudinal arch is flatter and less flexible because it makes contact with the ground. The longitudinal arches provide a firm base for support of the body in the upright position. The transverse arch is formed by the distal row of tarsal bones (cuboid, three cuneiforms) and the bases of the metatarsals that create a domed curve across the foot. The transverse arch is the major weight-bearing arch of the foot and helps distribute body weight over the base of the foot. The integrity of arches is maintained by the tarsal, tarsometatarsal, and intermetatarsal joints and their supporting ligaments (Fig. 10.117D).

CHAPTER 10  Lower Extremity

728

Third metatarsal

Second metatarsal

A

First metatarsal

Tarsometatarsal joints Intermediate cuneiform Medial cuneiform

R

L Navicular

Lateral cuneiform

Cuboid

Calcaneus

Talus

FIG. 10.129  Axial CT of left ankle and foot with navicular bone. P

A

Second metatarsal

First metatarsal First tarsometatarsal joint Intermediate cuneiform

Medial cuneiform

Lateral cuneiform

Navicular L

R

Talus Anterior subtalar joint

Sinus tarsi

Sustentaculum tali

Talus Tarsal canal

Posterior subtalar joint

Calcaneus

FIG. 10.130  Axial CT of left ankle P

and foot with cuneiform bones.

CHAPTER 10  Lower Extremity Second metatarsal

A

First proximal phalanx First metatarsal phalangeal joint First metatarsal

Third metatarsal Intermetatarsal joints

Intermediate cuneiform

Lateral cuneiform

Medial cuneiform

R

L

Cuboid

Calcaneus

P

FIG. 10.131  Axial CT scan of left ankle and foot with cuboid bone. A

First proximal phalanx First metatarsophalangeal joint

Second metatarsal

First metatarsal First tarsometatarsal joint

Third metatarsal

Medial cuneiform

Lateral cuneiform R

L

Cuboid Calcaneocuboid joint

Calcaneal tuberosity

Calcaneus P

FIG. 10.132  Axial CT of left ankle and foot with calcaneus.

729

730

CHAPTER 10  Lower Extremity Tibia

S

Talocrural joint Talus

Fibula Sustentaculum tali R

L

Calcaneus

I

FIG. 10.133  Coronal CT reformat of right ankle and foot with talus.

Tibia

S Medial malleoli

Talus Middle subtalar joint

Sinus tarsi L

R

Sustentaculum tali

Calcaneus

I

FIG. 10.134  Coronal CT reformat of right ankle and foot with calcaneus.

CHAPTER 10  Lower Extremity S

Navicular

R

L Cuboid

Fifth metatarsal I

FIG. 10.135  Coronal CT reformat of right ankle and foot with navicular and cuboid bones.

S

Navicular

Lateral cuneiform R

L

Cuboid

Fifth metatarsal

I

FIG. 10.136  Coronal CT reformat of right foot with lateral cuneiform bone.

731

CHAPTER 10  Lower Extremity

732

Intermediate cuneiform S

Medial cuneiform

Lateral cuneiform

R

L

Cuboid

Fifth metatarsal

I

FIG. 10.137  Coronal CT reformat of right foot with cuneiform bones.

Second metatarsal

S

First metatarsal

Third metatarsal Fourth metatarsal R

L

Fifth metatarsal

I

FIG. 10.138  Coronal CT reformat of right foot with metatarsals.

CHAPTER 10  Lower Extremity First metatarsal

Medial cuneiform

S

Navicular

733

Tibia

Talus Posterior subtalar joint A

P

Calcaneus

First proximal phalanx

Middle subtalar joint

Sesamoid bone

Sustentaculum tali

I

Tarsal canal

FIG. 10.139  Sagittal CT reformat of ankle and foot, medial aspect.

Navicular

S

Anterior subtalar joint

Tibia Talus

Middle cuneiform

Calcaneus A

P

Metatarsophalangeal joint Second proximal phalanx Second metatarsal Lateral cuneiform

Cuboid

I

Sinus tarsi

FIG. 10.140  Sagittal CT reformat of ankle and foot with talus.

734

CHAPTER 10  Lower Extremity Third metatarsal

Lateral cuneiform

Tibia

S

Lateral malleolus

Talus A

P

Fourth metatarsal

I

Cuboid

Calcaneus

FIG. 10.141  Sagittal CT reformat of ankle and foot, lateral aspect.

Retinacula, Fascia, and Ligaments Retinacula.  As in the wrist, fascia in various regions of

the ankle will thicken to form retinacula. The retinacula form sheaths for stabilizing tendons crossing over the joints of the ankle. They are called the flexor, extensor, and peroneal retinacula, after the tendons they serve (Figs. 10.142, 10.144, and 10.145). The flexor retinaculum extends between the medial malleolus and the medial tubercle of the calcaneus. It forms four tunnels, collectively called the tarsal tunnel, for the passage of the tendons of the tibialis posterior, flexor digitorum longus, and flexor hallucis longus muscles, as well as the posterior tibial vessels and nerve (Fig. 10.142). The extensor retinaculum consists of two portions: an upper portion (superior extensor retinaculum) and lower portion (inferior extensor retinaculum). The superior extensor retinaculum runs horizontally between the tibia and fibula just above the ankle joint. It extends over the tendons of the tibialis anterior and extensor hallucis muscles. The inferior extensor retinaculum splits into two bands that extend across the dorsum of the foot, originating from the upper surface of the calcaneus and sinus tarsi. The upper band of the inferior extensor retinaculum attaches to the medial malleolus, whereas the lower band extends to the fascia on the medial side of the foot. The tendons of the extensor digitorum longus and peroneus tertius muscles run deep to the inferior extensor retinaculum (Fig. 10.142). The peroneal retinacula split into two bands, forming the superior and inferior peroneal retinacula. The superior peroneal retinaculum extends from the lateral side of the calcaneus to the posterior border of the lateral malleolus. The inferior peroneal retinaculum extends from the lateral side of the calcaneus to blend with the fibers of the inferior extensor retinaculum. The superior and inferior peroneal retinacula transmit the tendons for the peroneus brevis and peroneus longus muscles (Figs. 10.142, 10.144, and 10.145).

Tarsal Tunnel Syndrome The tarsal tunnel is formed by the flexor retinaculum as it stretches between the medial malleolus and the calcaneus, creating a tunnel for the passage of the flexor tendons and neurovascular structures as they enter the foot. Tarsal tunnel syndrome is a condition that occurs from direct pressure on the tibial nerve as it courses through the tarsal tunnel along with the flexor tendons. Anything that causes swelling of the tissues running within or surrounding the tarsal tunnel can contribute to the condition, including inflammation, tumors, trauma, varicose veins, and diabetes. Typically, the syndrome presents as pain and/or a tingling sensation in the sole of the foot or at the site of compression. Commonly, the pain and numbness are aggravated with activity, as in long periods of standing or walking. Treatment options include eliminating the source of the compression with anti-inflammatory medication, orthotics, cortisone injections, and, if necessary, surgery.

Fascia.  In addition to the retinacula, another area of thickened fascia is located on the plantar surface of the foot. The plantar fascia (aponeurosis) is approximately 80 layers thick, creating some of the thickest fascia within the human body. It begins at the inferior aspect of the calcaneus and spreads anteriorly into five separate slips that create the fibrous flexor sheaths of the toes (Figs. 10.121, 10.124, and 10.125). The plantar fascia is extremely important for maintaining the longitudinal arch of the foot. Ligaments.  Other support structures of the ankle and

foot include a complex architecture of multiple ligaments

CHAPTER 10  Lower Extremity that provide necessary stability. The ligaments of the ankle and foot can be identified in Figs. 10.143–10.161. The main support structures of the ankle include the deltoid ligament, lateral ligaments, spring (plantar) ligament, and interosseous ligament. The deltoid ligament provides medial support and is the strongest ligament in the ankle joint. It arises from the medial malleolus and fans out into deep and superficial bands that include the anterior and posterior tibiotalar, tibiocalcaneal, tibionavicular, and tibiospring ligaments, which insert on the talus, calcaneus, navicular bones, and spring ligament, respectively (Figs. 10.143A, 10.145– 10.147, 10.156, and 10.157). The lateral border of the ankle joint is strengthened by several ligaments termed the anterior talofibular, calcaneofibular, posterior talofibular, anterior tibiofibular, and posterior tibiofibular

Extensor digitorum longus muscle and tendon

Extensor hallucis longus Synovial sheath of extensor digitorum longus Extensor hallucis brevis Extensor digitorum longus

Fibula Peroneus longus muscle Inferior extensor retinaculum Achilles Superior peroneal retinaculum Inferior peroneal retinaculum Peroneus longus Peroneus brevis

Extensor digitorum brevis Tuberosity of fifth metatarsal

Peroneus tertius

735

ligaments (Figs. 10.143B, C, and D; 10.144–10.148; 10.155; and 10.156). All of these ligaments originate at the fibular malleolus and insert on the adjacent bone structures. The spring (plantar) ligament is a triangular band of fibers that arises from the sustentaculum tali and attaches to the posterior surface of the navicular bone (Figs. 10.121, 10.148, and 10.149). It is an important ligament in maintaining the longitudinal arch of the foot. A strong band of tissue binding the talus to the calcaneus is the interosseous talocalcaneal ligament, which is obliquely oriented in the tarsal canal and helps limit eversion (Figs. 10.121, 10.143C, 10.147, and 10.156). The cervical ligament located in the sinus tarsi helps limit inversion of the ankle (Figs. 10.121, 10.122, 10.124, 10.143C, 10.147, 10.152, 10.153, 10.156, and 10.157).

Tibia

Synovial sheath of tibialis posterior Flexor digitorum longus Flexor hallucis longus Achilles

Synovial sheath of tibialis anterior Inferior extensor retinaculum Tibialis posterior Extensor hallucis longus Abductor hallucis

Flexor retinaculum Abductor hallucis

Tarsal tunnel Flexor Flexor digitorum brevis digitorum longus

Flexor hallucis longus

FIG. 10.142  Tendons and retinacula of left foot. Left, Lateral aspect. Right, Medial aspect.

S S Tibia

Fibula Interosseous membrane

Tibia Deltoid ligament:

Anterior tibiotalar Posterior tibiotalar Tibiocalcaneal Tibionavicular Tibiospring

Talus Medial talocalcaneal ligament

A

P

Talonavicular ligament

A

L Posterior tibiotalar ligament

Spring (plantar) ligament

Posterior talofibular ligament

Tibiocalcaneal ligament

Talus Calcaneofibular ligament

Medial talocalcaneal ligament

I

Navicular

Posterior tibiofibular ligament R Lateral malleolus

Medial malleolus

Calcaneus

B

I

FIG. 10.143  (A) Ligaments of right foot, medial view. (B) Ligaments of right foot, posterior view.

Posterior talocalcaneal ligament

736

CHAPTER 10  Lower Extremity S Tibia

Fibula

Anterior tibiofibular ligament Anterior talofibular ligament

Posterior tibiofibular ligament

Interosseous talocalcaneal ligament Talus Talonavicular ligament Navicular

Posterior talofibular ligament

Dorsal cuboideonavicular ligament A

Calcaneus

Cuboid

P I Calcaneofibular ligament

Calcaneocuboid ligament

Long plantar ligament

Lateral talocalcaneal ligament

C

S

Fibula

Tibia

Anterior tibiofibular ligament

Talus

Anterior talofibular ligament

Anterior tibiotalar ligament

Calcaneofibular ligament Lateral talocalcaneal ligament

Tibionavicular ligament

Calcaneus

Talonavicular ligament

Calcaneocuboid ligament Cuneonavicular ligaments Intercuneiform ligaments

Tuberosity of fifth metatarsal R

Tarsometatarsal ligaments L

Metatarsal ligaments Fifth metatarsal

First metatarsal

Deep transverse metatarsal ligament Fifth proximal phalanx

Joint capsule of metatarsophalangeal joint

Fifth middle phalanx Fifth distal phalanx

Joint capsules of interphalangeal joints I Collateral ligaments

D

Anterior view

FIG. 10.143, cont’d  (C) Ligaments of right foot, lateral view. (D) Ligaments of right foot, anterior view.

CHAPTER 10  Lower Extremity Tibialis anterior tendon

Inferior extensor retinaculum

A

Greater saphenous vein

Extensor hallucis longus tendon

Tibia

Extensor digitorum longus tendon

Tibialis posterior tendon

Anterior tibiofibular ligament R

L

Posterior tibiofibular ligament

Flexor digitorum longus tendon

Fibula

Tibial artery and vein Tibial nerve

Peroneus longus tendon

Flexor retinaculum

Peroneus brevis tendon and muscle

Flexor hallucis longus muscle Plantaris tendon

Superior peroneal retinaculum Achilles tendon

P

Soleus muscle

FIG. 10.144  Axial, T1-weighted MRI of right ankle.

Extensor hallucis longus tendon

A

Tibialis Great anterior saphenous tendon vein

Extensor digitorum longus tendon

Deltoid ligament

Extensor retinaculum

Talus Medial malleolus

Anterior talofibular ligament

Tibialis posterior tendon

R

L

Talocrural joint

Flexor digitorum longus tendon

Lateral malleolus

Flexor retinaculum

Posterior talofibular ligament

Flexor hallucis longus muscle and tendon

Superior peroneal retinaculum

Plantaris tendon Achilles tendon

Peroneus longus tendon Peroneus brevis muscle and tendon

P

Posterior tibiofibular ligament

FIG. 10.145  Axial, T1-weighted MRI of right ankle.

737

738

CHAPTER 10  Lower Extremity A Extensor hallucis longus tendon

Tibialis anterior tendon

Extensor digitorum brevis tendon

Navicular Deltoid ligament

Talus (head) Interosseous talocalcaneal ligament

Tibialis posterior tendon L

R Talus (neck)

Flexor digitorum longus tendon

Calcaneofibular ligament

Talus (body)

Fibula Posterior tibial artery and vein

Peroneus longus tendon

Flexor hallucis longus tendon Plantaris tendon Peroneus brevis tendon

P

Achilles tendon

FIG. 10.146  Axial, T1-weighted MRI of right ankle. Intermediate cuneiform

A

Medial cuneiform

Tibialis anterior tendon

Extensor digitorum longus tendon

Navicular Extensor digitorum brevis muscle

Talonavicular joint Talus (head)

Interosseous talocalcaneal ligament

Tibialis posterior tendon L

R Talus (body)

Deltoid ligament

Calcaneofibular ligament

Flexor digitorum longus tendon

Peroneus brevis tendon

Flexor hallucis longus tendon

Peroneus longus tendon

Calcaneus Achilles tendon P

FIG. 10.147  Axial, T1-weighted MRI of right ankle.

CHAPTER 10  Lower Extremity A Tibialis anterior tendon

Intermediate cuneiform

Medial cuneiform Tibialis posterior tendon

Lateral cuneiform

Spring (plantar) ligament

Extensor digitorum brevis muscle

Adductor hallucis muscle

Cuboid

Flexor digitorum longus tendon L

R Peroneus brevis tendon

Flexor hallucis longus tendon

Peroneus longus tendon

Quadratus plantae muscle

Calcaneus

Achilles tendon P

FIG. 10.148  Axial, T1-weighted MRI of right ankle. A Extensor digitorum brevis muscle

Flexor hallucis longus tendon

Cuboid Spring (plantar) ligament

Quadratus plantae muscle

Peroneus brevis tendon L

R

Abductor hallucis muscle

Peroneus longus tendon

Flexor digitorum brevis muscle Calcaneus

P

FIG. 10.149  Axial, T1-weighted MRI of right ankle.

739

740

CHAPTER 10  Lower Extremity A Adductor hallucis muscle Flexor hallucis brevis muscle

Cuboid Peroneus brevis tendon

Abductor hallucis brevis muscle

Peroneus longus tendon L

R Quadratus plantae muscle Abductor digiti minimi muscle

P

FIG. 10.150  Axial, T1-weighted MRI of right ankle.

Tibialis posterior tendon

S

Flexor digitorum longus tendon

Tibialis anterior tendon Medial malleolus

Deltoid ligament A

P Flexor hallucis longus tendon

Navicular

Medial cuneiform

Abductor hallucis muscle

I

FIG. 10.151  Sagittal, T1-weighted MRI of ankle ligaments and tendons.

CHAPTER 10  Lower Extremity

S

Flexor hallucis longus muscle

Soleus muscle

Tibia Talus

Flexor hallucis longus tendon

A

P Tarsal canal Achilles tendon

Medial cuneiform

Navicular

Flexor hallucis longus tendon

I

Quadratus plantae muscle

Interosseous talocalcaneal ligament

FIG. 10.152  Sagittal, T1-weighted MRI of ankle ligaments and tendons.

S

Talus

Soleus muscle Achilles tendon Extensor hallucis longus tendon

Flexor hallucis longus muscle

Extensor digitorum longus tendon

P A

Sinus tarsi

Cervical ligament

Posterior facet

Medial cuneiform Lateral cuneiform Cuboid

Navicular

I

Calcaneus

FIG. 10.153  Sagittal, T1-weighted MRI of ankle ligaments and tendons.

741

742

CHAPTER 10  Lower Extremity S

Peroneus brevis muscle

Extensor digitorum longus muscle A

P

Fibula

Peroneus longus tendon

Cuboid I

FIG. 10.154  Sagittal, T1-weighted MRI of ankle ligaments and tendons.

S Tibia

Flexor hallucis longus muscle

Talocrural joint

Interosseous membrane

Tibialis posterior tendon

Fibula

Flexor digitorum longus tendon

Lateral malleolus L

R Posterior tibiotalar (deltoid) ligament

Posterior talofibular ligament

Talus

Peroneus brevis tendon

Flexor hallucis longus tendon

Peroneus longus tendon

Abductor hallucis muscle

Posterior subtalar joint

Flexor digitorum brevis muscle

Calcaneus

Plantar fascia Quadratus plantae muscle

I

Abductor digiti minimi muscle

FIG. 10.155  Coronal, T1-weighted MRI of left ankle.

CHAPTER 10  Lower Extremity Tarsal canal

S

Extensor digitorum longus muscle

Tibia Medial malleolus

Talus Lateral malleolus

Anterior tibiotalar ligament (deltoid)

Interosseous talocalcaneal ligament

Posterior tibialis tendon Flexor retinaculum

Posterior talofibular ligament

R L

Flexor digitorum longus tendon Middle subtalar joint

Quadratus plantae muscle Peroneus brevis tendon Calcaneofibular ligament

Sustentaculum tali

Peroneus longus tendon

Abductor hallucis muscle

Abductor digiti minimi muscle

Flexor hallucis longus tendon

Flexor digitorum brevis muscle

Flexor digitorum brevis muscle Plantar fascia

I

Calcaneus

FIG. 10.156  Coronal, T1-weighted MRI of left ankle. Tibialis anterior muscle

Extensor hallucis longus muscle

S

Tibia Extensor digitorum longus muscle

Medial malleolus

Deltoid

Tibiotalar ligament Talus

Tibiospring ligament

Sinus tarsi

Flexor retinaculum R

L

Tibialis posterior tendon

Cervical ligament

Flexor digitorum longus tendon

Calcaneus Peroneus brevis tendon

Abductor hallucis muscle

Peroneus longus tendon

Flexor hallucis longus tendon

Abductor digiti minimi muscle

Quadratus plantae muscle Flexor digitorum brevis muscle

I

Plantar fascia

FIG. 10.157  Coronal, T1-weighted MRI of left ankle.

743

744

CHAPTER 10  Lower Extremity Tibialis anterior tendon

S

Extensor hallucis longus tendon Extensor hallucis brevis muscle

Extensor digitorum longus tendon

Head of talus

Extensor digitorum brevis muscle

Navicular L

R

Cuboid

Tibialis posterior tendon

Spring (plantar) ligament

Abductor hallucis muscle

Peroneus brevis tendon

Flexor hallucis longus tendon

Peroneus longus tendon

Flexor digitorum longus muscle

Adductor digiti minimi muscle

Quadratus plantae muscle

Plantar fascia

I

Flexor digitorum brevis muscle

FIG. 10.158  Coronal, T1-weighted MRI of left foot.

Tibialis anterior tendon

Extensor hallucis longus tendon

S

Extensor digitorum longus tendon

Extensor digitorum brevis muscle

Extensor hallucis brevis muscle L

R Navicular

Cuboid

Tibialis posterior tendon

Peroneus brevis tendon

Abductor hallucis muscle

Peroneus longus tendon

Flexor hallucis longus tendon

Abductor digiti minimi muscle

Flexor digitorum longus tendon

Flexor digitorum brevis muscle

I

Quadratus plantae muscle

FIG. 10.159  Coronal, T1-weighted MRI of left foot.

CHAPTER 10  Lower Extremity Extensor hallucis longus tendon

S

745

Extensor hallucis brevis muscle Lateral cuneiform

Tibialis anterior tendon

Extensor digitorum brevis muscle

Cuneonavicular joint

Cuboid L

R

Spring (plantar) ligament

Tibialis posterior tendon

Peroneus brevis tendon

Abductor hallucis muscle

Fifth metatarsal (base)

Flexor hallucis longus muscle

Abductor digiti minimi muscle

Flexor digitorum longus tendon

Peroneus longus muscle and tendon Plantar fascia

I Flexor digitorum brevis muscle

Quadratus plantae muscle

FIG. 10.160  Coronal, T1-weighted MRI of left foot.

Intermediate cuneiform

S

Extensor digitorum brevis muscle

Lateral cuneiform

Medial cuneiform Extensor digitorum longus muscle Tibialis anterior tendon L

R Abductor hallucis muscle

Fourth metatarsal (base)

Flexor hallucis brevis muscle

Fifth metatarsal Abductor digiti minimi muscle

Flexor hallucis longus tendon

Interosseous muscle

Peroneus longus tendon Flexor digitorum Plantar longus tendon fascia

Flexor digiti minimi brevis muscle Quadratus plantae muscle

I

Flexor digitorum Adductor hallucis brevis muscle muscle (oblique head)

FIG. 10.161  Coronal, T1-weighted MRI of left foot.

CHAPTER 10  Lower Extremity

746

Ligaments of the Toes.  The metatarsophalangeal

of the metatarsophalangeal joint. The collateral ligaments extend from the heads of the metatarsals, fanning out to attach to the bases of the proximal phalanges. The heads of the second through fifth metatarsals are interconnected by the deep transverse metatarsal ligament. In a similar manner as the metatarsophalangeal joints, the interphalangeal joints are strengthened medially and laterally by collateral ligaments and on the plantar surface by the plantar plate (Figs. 10.143D and 10.162–10.164).

joint is strengthened medially and laterally by strong collateral ligaments, dorsally from fibers of the extensor tendons, and underneath by the plantar plate. The plantar plate (ligament) is a firm fibrocartilaginous structure that attaches to the base of the proximal phalanges, the collateral ligaments, and the deep transverse metatarsal ligaments. The plantar plate functions as the insertion point for the tendons, ligaments, and other stabilizing structures

Extensor hallucis longus Second metatarsal tendon

Extensor retinaculum

Extensor hallucis brevis tendon

Third metatarsal

S

Lumbrical tendon

Fourth metatarsal Fifth metatarsal

First metatarsal Medial collateral ligament

Plantar plate

R L

Abductor hallucis tendon Flexor hallucis brevis tendon (medial head) Flexor hallucis Flexor hallucis longus tendon brevis tendon (lateral head)

Adductor hallucis tendon

I

Plantar fascia

Flexor digitorum brevis tendons

FIG. 10.162  Coronal, T1-weighted MRI of metatarsals.

First proximal First metatarsal phalanx (head) S

Plantar plate

Extensor hallucis longus tendon A

P

First distal phalanx

Flexor hallucis longus tendon

I

Flexor hallucis brevis muscle

Lumbrical muscle

FIG. 10.163  Sagittal, T1-weighted MRI of great toe.

CHAPTER 10  Lower Extremity

747

A

First proximal phalanx Lateral collateral ligament Medial collateral ligament First metatarsal (head)

Interosseous muscles L

R

Flexor hallucis brevis muscle

Abductor hallucis muscle

Fourth metatarsal (base)

Cuboid

P

FIG. 10.164  Axial, T1-weighted MRI of foot.

Tendons The musculotendinous structures of the ankle can be divided into posterior, anterior, medial, and lateral groups.

Posterior Group.  The posterior group is composed

of the single Achilles tendon, the largest and most powerful tendon of the body. The Achilles tendon arises from the gastrocnemius and soleus muscles and attaches to the calcaneal tuberosity on the posterior aspect of the calcaneus (Figs. 10.115, 10.121, 10.144–10.148, 10.152, and 10.153).

Anterior Group.  The anterior group is made up of

the tibialis anterior, extensor hallucis longus, and extensor digitorum longus tendons, which are listed medial to lateral and act to extend and dorsiflex the foot. The tibialis anterior muscle becomes tendinous at the distal tibia and attaches to the plantar and medial aspects of the first cuneiform and metatarsal bones. The tendon of the extensor hallucis longus muscle originates from the anterior fibula and inserts on the great toe. The most lateral of this group is the extensor digitorum longus tendon, which originates at the level of the lateral malleolus and inserts on the second through the fifth digits

CHAPTER 10  Lower Extremity

748

(Figs. 10.142, 10.144–10.148, 10.151, 10.153, 10.156– 10.163, and 10.165).

Medial Group.  The medial group is composed of the

posterior tibialis tendons, flexor digitorum longus, and flexor hallucis longus tendons, which act as a group to invert and plantar flex the foot. The tibialis posterior tendon fans out in multiple strands that insert on the plantar aspect of the sustentaculum tali, navicular, medial cuneiform, and second through fourth metatarsals. Coursing posterior and lateral to the tibialis posterior tendon is the flexor digitorum longus tendon, which inserts on the second through fourth phalanges. The tendon of the flexor hallucis longus muscle curves under the sustentaculum tali and then courses along the plantar surface of the foot to insert on the great toe (Figs. 10.142, 10.144–10.148, 10.151, 10.152, 10.155– 10.163, and 10.165).

Lateral Group.  The two peroneus tendons, the pero-

neus longus and peroneus brevis, make up the lateral group and act to evert and weakly plantar flex the foot, S

Patella

Head of fibula

as well as stabilize the ankle joint laterally. These two tendons share a common tendinous sheath behind the lateral malleolus. Below the malleolus, they diverge into separate tendon sheaths, with the peroneus brevis tendon inserting on the base of the fifth metatarsal and the peroneus longus tendon curving beneath the calcaneus to insert on the base of the first metatarsal and medial cuneiform bones (Figs. 10.142, 10.144–10.149, 10.154– 10.161, and 10.165).

Muscles of the Foot The muscles of the foot are divided into the muscles of the dorsum and muscles of the sole of the foot. These muscles are shown in Figs. 10.147–10.167 and described in Table 10.4.

Muscles of the Dorsum of the Foot.  The dorsal

muscles include the extensor digitorum brevis and the extensor hallucis brevis muscles, which form a fleshy mass on the lateral part of the dorsal foot. The extensor digitorum brevis muscle arises from the anterior, upper surface of the calcaneus and passes obliquely across the dorsum to end in three tendons that insert onto the dorsal aponeurosis of the second through fourth digits, deep to the tendons of the extensor digitorum longus muscle (Fig. 10.165). The extensor digitorum brevis muscle is responsible for dorsiflexion of the second through fourth digits. The extensor hallucis brevis muscle splits off of the extensor digitorum brevis muscle to insert on the dorsal aponeurosis of the first toe. It acts to dorsiflex the first digit.

Muscles of the Sole of the Foot.  The muscles of the sole of the foot can be described by four muscular layers.

Gastrocnemius muscle Extensor digitorum longus muscle

Soleus muscle A

Tibialis anterior muscle

Peroneus longus muscle P Peroneus brevis muscle Flexor hallucis longus muscle

Extensor hallucis longus tendon Peroneus tertius tendon Superior and inferior extensor retinacula

Lateral malleolus Fibular retinaculum

I Extensor digitorum Fifth brevis muscle metatarsal

FIG. 10.165  Extensor tendons of the lower leg.

First Layer.  The muscles located within the first layer are the most superficial and include, from medial to lateral, the abductor hallucis, flexor digitorum brevis, and abductor digiti minimi muscles (Figs. 10.121, 10.124, 10.164, 10.166A, and 10.167). The abductor hallucis muscle arises from the medial process of the calcaneal tuberosity and lies along the medial border of the foot to insert on the medial base of the proximal phalanx of the first digit. The flexor digitorum brevis muscle also arises from the medial process of the calcaneal tuberosity, as well as the plantar aponeurosis, to insert on both sides of the middle phalanges of the lateral four digits. The abductor digiti minimi muscle arises from the lateral process of the calcaneal tuberosity, the tuberosity of the fifth metatarsal, and the plantar aponeurosis to form the lateral margin of the foot. It inserts on the lateral side of the base of the proximal phalanx of the fifth digit. Second Layer.  This layer is located deep to the first layer and includes the quadratus plantae and lumbrical muscles (Figs. 10.121, 10.124, 10.155–10.161, 10.163, and 10.166B). The quadratus plantae muscle is a small,

CHAPTER 10  Lower Extremity

Tendon of flexor hallucis longus

Lumbricals Flexor digiti minimi brevis

Lumbricals

Flexor hallucis brevis

Flexor digiti minimi brevis

Flexor digitorum brevis

Quadratus plantae

Abductor hallucis

Abductor digiti minimi

749

Flexor hallucis brevis

Abductor digiti minimi

Flexor digitorum longus tendon (cut) Flexor digitorum brevis tendon (cut)

Peroneus (fibularis) longus tendon

Flexor hallucis longus tendon Calcaneal tuberosity

A

B

Adductor hallucis (transverse head) Interosseous muscles

Adductor hallucis (oblique head)

Flexor digiti minimi brevis

Flexor hallucis brevis

Fibularis longus tendon

Dorsal interossei

Plantar interossei

Flexor digitorum longus tendon Flexor hallucis longus tendon

D C

Plantar view

Dorsal view

FIG. 10.166  Muscle layers of right foot. (A) First layer. (B) Second layer. (C) Third layer. (D) Fourth layer.

750

CHAPTER 10  Lower Extremity

flat muscle that arises as two small slips from the medial and lateral margins of the plantar surface of the calcaneus and joins with the lateral side of the flexor digitorum longus tendon that continues to the distal phalanges of the lateral four digits. The four small lumbrical muscles arise from the medial surfaces of the individual tendons of the flexor digitorum longus. They insert on the medial margin of the proximal phalanges of the second through fifth digits and extend into the extensor aponeurosis. Third Layer.  The third layer consists of three muscles: the flexor hallucis brevis, adductor hallucis, and flexor digiti minimi brevis muscles (Figs. 10.121, 10.161, 10.164, 10.166C, and 10.167). The flexor hallucis brevis muscle arises from the medial cuneiform bone and the tibialis posterior tendon. It splits into two tendons that cover the plantar surface of the first metatarsal, extending to both sides of the base of the proximal phalanx of the first digit. The two sesamoid bones associated with the first metatarsal are embedded within the flexor hallucis brevis tendons. The adductor hallucis muscle has two heads; the oblique head arises from the cuboid

and lateral cuneiform bones and the bases of the second and third metatarsals, and the transverse head arises from the deep transverse metatarsal ligament and the metatarsal joint capsule. Both heads insert on the lateral side of the base of the proximal phalanx of the first digit. The slender flexor digiti minimi brevis muscle arises from the base of the fifth metatarsal and inserts on the base of the proximal phalanx of the fifth digit. Fourth Layer.  This layer consists of the interosseous muscles (Figs. 10.121, 10.164, 10.166D, and 10.167). Three plantar and four dorsal interossei muscles are located between the metatarsal bones. The plantar interosseous muscles arise from the bases and medial surfaces of the third through fifth metatarsals and insert on the medial sides of the bases of the proximal phalanges of the third through fifth digits. The dorsal interosseous muscles are larger than their plantar counterparts, arising from adjacent surfaces of the metatarsal bones and extending to attach to the sides of the proximal phalanx and capsules of the metatarsal phalangeal joints of the second through fourth digits.

Dorsal interosseous II Tendons of extensor digitorum brevis

S

Deep fascia of dorsum of foot

Dorsal interosseous I Tendons of extensor hallucis brevis

Plantar interosseous I

Tendons of extensor digitorum longus

Tendon of extensor hallucis longus

Dorsal interosseous III

Dorsal interosseous IV Dorsal fascia of foot

Metatarsal I

Opponens digiti minimi Superficial fascia of sole of foot

Abductor hallucis

Abductor digiti minimi Flexor digiti minimi brevis

Plantar interosseous III

Tendons of flexor digitorum longus and lumbricals

Plantar interosseous II

Plantar fascia

I

Deep fascia of sole of foot

Flexor hallucis brevis Tendon of flexor hallucis longus Adductor hallucis, oblique head

Flexor digitorum brevis

FIG. 10.167  Coronal view of muscles of foot at metatarsals.

CHAPTER 10  Lower Extremity TABLE 10.4 Muscle

751

Muscles of the Foot Proximal Insertion

Dorsum of Foot Extensor Anterosuperior surface of calcaneus digitorum brevis Extensor hallucis Extensor digitorum brevis muscle brevis Sole of Foot First Layer Abductor hallucis Medial process of calcaneal tuberosity

Distal Insertion

Action

Dorsal aponeurosis of second to fourth digits

Dorsiflexion of metatarsophalangeal joint of great toe and second to fourth toes

Base of proximal phalanx of great toe

Dorsiflexes the first digit

Medial base of proximal phalanx of first digit Both sides of middle phalanges of second to fifth digits

Abducts first toe from second; flexes metatarsophalangeal joint Flexes metatarsophalangeal and proximal interphalangeal joints of second to fifth digits Abducts fifth toe and flexes metatarsophalangeal joint

Flexor digitorum brevis

Medial process of calcaneal tuberosity and plantar aponeurosis

Abductor digiti minimi Second Layer Quadratus plantae Lumbrical

Lateral process of calcaneal tuberosity, fifth metatarsal

Proximal phalanx of fifth digit

Calcaneus, plantar surface

Distal phalanges of second to fifth digits Medial margins of proximal phalanges of second to fifth digits

Assists the flexor digitorum longus in flexion of toes Flexes metatarsophalangeal joints; extends proximal and distal interphalangeal joints of second to fifth digits

Medial cuneiform and tibialis posterior tendon Oblique head: cuboid, lateral cuneiform, and second and third metatarsals Transverse head: deep transverse metatarsal ligament and metatarsal joint capsule Base of fifth metatarsal

Proximal phalanx of first digit, both sesamoid bones Lateral side of base of the proximal phalanx of first digit

Flexes metatarsophalangeal joint of first toe Adducts first toe toward second and flexes first toe

Base of the proximal phalanx of fifth digit

Flexes metatarsophalangeal joint of fifth digit

Bases and medial surfaces of third to fifth metatarsals

Medial sides of the bases of the proximal phalanges of third to fifth digits

Metatarsals

Proximal phalanx and capsules of metatarsal phalangeal joints of second to fourth digits

Adducts third to fifth toes, flexes metatarsophalangeal, and extends interphalangeal joints of third to fifth digits Abducts second to fourth digits away from midline, flexes metatarsophalangeal joints, and extends interphalangeal joints of second to fourth digits

Third Layer Flexor hallucis brevis Adductor hallucis

Flexor digiti minimi Fourth Layer Plantar interosseous Dorsal interosseous

Flexor digitorum longus tendons

752

CHAPTER 10  Lower Extremity external pudendal arteries (Fig. 10.174). The largest deep branch of the femoral artery is the profunda femoris artery, which arises from the posterolateral aspect of the femoral artery about 4 cm below the inguinal ligament and runs distally behind the femoral artery (Figs. 10.168, 10.169, and 10.171–10.174). It passes between the vastus medialis muscle and the muscles of the adductor group. The profundus femoris gives off two large branches: the medial and lateral circumflex femoral arteries (Figs. 10.168, 10.169, 10.173, and 10.174). The branches curve around the proximal femur and hip joint to supply the muscles of the adductor group and parts of the gluteal musculature, as well as the extensors and flexors at the thigh. The terminal branches of the profunda femoris artery are the perforating arteries (3–5) near the linea aspera that pass through the adductor muscles (Figs. 10.168, 10.173, and 10.174).

NEUROVASCULATURE Arteries Femoral.  Traveling vertically along the anteromedial aspect of the hip is the femoral artery. The femoral artery, an extension of the external iliac artery, enters the anterior compartment of the thigh beneath the inguinal ligament, where it is relatively superficial and easily palpable (Figs. 10.168–10.173). It descends the thigh and continues through the opening in the adductor magnus muscle as the popliteal artery in the knee. The femoral artery and its main branches, superficial and deep, supply all the compartments of the thigh, as well as the skin of the anterior abdominal wall, inguinal region, and external genitalia. The superficial branches of the femoral artery accompany the veins of the hip and include the inferior epigastric, superficial circumflex iliac, and the

S Abdominal aorta

Inferior epigastric artery

Common iliac artery Median sacral artery

Iliolumbar artery Deep circumflex iliac artery

L5 vertebra Internal iliac artery

External iliac artery Superior gluteal artery

Lateral sacral artery

Inguinal ligament Lateral circumflex femoral artery

Obturator artery Inferior gluteal artery

Medial circumflex femoral artery

Internal pudendal artery

Profunda femoris artery

External pudendal artery

L R

Femoral artery

Lateral circumflex femoral artery

Perforating branches of profunda femoris artery

Descending genicular artery I

FIG. 10.168  Anterior view of iliac and femoral arteries.

CHAPTER 10  Lower Extremity External Internal iliac artery iliac artery

S

Aorta

753

Common iliac artery

Femoral artery Profunda femoris artery Lateral circumflex artery R

L Popliteal artery

I

FIG. 10.169  3D CTA of iliac and femoral arteries.

Popliteal.  The popliteal artery is the continuation of the femoral artery. It runs deep near the bones of the knee joint during its course through the popliteal fossa. It passes distally over the popliteus muscle and divides into the anterior and posterior tibial arteries (Figs. 10.173– 10.176). The popliteal artery accompanies the popliteal vein and tibial nerve. The tibial nerve is the most superficial structure in the popliteal fossa (Figs. 10.177 and 10.178). The popliteal artery supplies the surrounding muscles and forms a substantial plexus of articular branches anastomosing around the knee joint. The popliteal artery gives off branches to portions of the thigh muscles near the knee joint, dispatches the sural arteries distally to the gastrocnemius muscle, and supplies the knee joint with the anastomosing genicular arteries (lateral superior, lateral inferior, medial superior, medial inferior, and descending) (Fig. 10.174). Anterior Tibial.  The anterior tibial artery courses an-

teriorly at the level of the fibular head into the anterior compartment of the lower leg. It runs distally as far as

the anterior side of the ankle, where it becomes the dorsalis pedis artery. The branches of the anterior tibial artery are the posterior tibial recurrent, the anterior tibial recurrent, the medial anterior malleolar, the lateral anterior malleolar, and numerous muscular branches (Figs. 10.174–10.176).

Posterior Tibial.  The posterior tibial artery is usually larger than the anterior tibial artery. As it passes distally in the posterior compartment, it courses toward the medial side of the leg. The posterior tibial artery terminates by dividing into the medial and lateral plantar arteries in the foot. The peroneal (fibular) artery arises from the posterior tibial artery approximately 2 cm below the distal border of the popliteus muscle. It descends posteriorly along the medial aspect of the fibula and terminates on the lateral surface of the calcaneal tuberosity. Branches of the peroneal artery include the fibular, communicating, perforating, posterior lateral malleolar, and lateral calcaneal, as well as numerous muscular and cutaneous branches (Figs. 10.174–10.176).

754

CHAPTER 10  Lower Extremity Rectus femoris muscle

Sartorius muscle

A

Femoral artery

Femoral vein

Tensor fasciae latae muscle

Pectineus muscle Superior ramus of pubis

Iliotibial (IT) band

Obturator internus muscle

Gluteus medius muscle R

L

Prostate Rectum

Iliopsoas muscle

Acetabular fossa Femoral head

Greater trochanter

Inferior gemellus muscle Sciatic nerve

Gluteus maximus muscle

P

Ischium

Ischial spine

FIG. 10.170  Axial, contrast-enhanced CT of right hip with femoral artery.

Sartorius muscle

Profunda femoris artery

Femoral artery

A

Rectus femoris muscle

Femoral vein

Tensor fasciae latae muscle

Pectineus muscle Adductor longus muscle

Iliopsoas muscle Vastus lateralis muscle

Adductor brevis muscle R

L

Femur Quadratus femoris muscle Adductor magnus muscle

Gluteus maximus muscle

P

Sciatic nerve

Ischium

FIG. 10.171  Axial, contrast-enhanced CT of right hip with femoral artery and vein.

CHAPTER 10  Lower Extremity Rectus femoris muscle

Sartorius muscle

A

755

Pectineus muscle

Femoral artery

Body of pubis

Tensor fasciae latae muscle

Iliopsoas muscle

Femoral vein Adductor longus muscle

R

L

Vastus lateralis muscle

Prostate Profunda femoris artery

Greater trochanter

Obturator internus muscle

Quadratus femoris muscle

Gluteus maximus muscle

P

Ischium

FIG. 10.172  Axial, contrast-enhanced CT of right hip with profundus femoris artery. S

Left external iliac artery

Ascending branch

Left profundus femoris artery Left lateral circumflex femoral artery

Right lateral circumflex femoral artery

Left medial circumflex femoral artery

Descending branch

Perforating branches of profundus femoris Left femoral artery

L

R

Left popliteal artery

FIG. 10.173  3D CT of femoral artery.

I

756

CHAPTER 10  Lower Extremity Aorta

S

S

External iliac artery

Deep circumflex iliac artery

Common iliac artery

Superior gluteal artery

Internal iliac artery Inferior epigastric artery

Inferior gluteal artery

Superficial circumflex iliac artery

External pudendal artery Obturator artery

Medial circumflex femoral artery

Profunda femoris artery

Medial circumflex femoral artery

Profunda femoris artery

Lateral circumflex femoral artery

Femoral artery Femoral artery

Perforating arteries Descending genicular artery Popliteal artery

Site of hiatus in adductor magnus

Descending branch

Medial superior genicular artery

Medial superior genicular artery

Lateral superior genicular artery Popliteal artery

Medial inferior genicular artery

Sural artery

Lateral inferior genicular artery

Anterior tibial recurrent artery

Anterior tibial artery

Anterior tibial artery

Peroneal (fibular) artery Perforating branch of peroneal (fibular) artery

Medial anterior malleolar artery

Medial inferior genicular artery

Posterior tibial artery

Perforating branch

Lateral anterior malleolar artery

Dorsalis pedis artery

Lateral tarsal artery

Medial tarsal artery Deep plantar branch

Arcuate artery

First dorsal metatarsal artery

Dorsal digital arteries I

Medial plantar artery

Lateral plantar artery Plantar arch Plantar metatarsal artery

Deep branch of dorsalis pedis artery

Plantar digital arteries I

FIG. 10.174  Arteries of lower extremity. Left, Anterior view. Right, Posterior view.

CHAPTER 10  Lower Extremity Medial inferior genicular artery

Popliteal artery

Popliteal artery

Anterior tibial artery

Peroneal (fibular) artery

Descending genicular artery

757

S

Anterior tibial artery

Posterior tibial artery

Peroneal (fibular) artery R

L

Lateral anterior malleolar artery

Posterior tibial artery Lateral plantar artery

Medial plantar artery

I

Medial plantar artery

FIG. 10.176  CT MIP of lower leg arteries.

FIG. 10.175  3D CT angiography of tibial and fibular arteries.

Veins There are two groups of veins in the lower extremity: superficial and deep. The superficial veins arise in the foot from the dorsal venous arch and merge chiefly into two main trunks, the great saphenous and the small saphenous veins. The great saphenous vein ascends the medial aspect of the leg and thigh to drain into the femoral vein near the hip joint. From the lateral side of the foot, the small saphenous vein passes posterolaterally to join the popliteal vein (Fig. 10.179). Between these two superficial veins and the system of the deep veins are numerous deep anastomoses. The deep veins

accompany their corresponding arteries and include the anterior and posterior tibial veins, which unite to form the popliteal vein on the posterior aspect of the knee. The popliteal vein becomes the superficial femoral vein in the distal thigh. As the superficial femoral vein ascends the thigh, it joins with the profunda femoris vein, which drains the thigh muscles, and becomes the femoral vein, which courses medial to the femoral artery. The femoral vein joins with the greater saphenous vein in the proximal thigh and then continues deep to the inguinal ligament as the external iliac vein (Figs. 10.40–10.48, 10.102–10.109, 10.170–10.172, 10.179, and 10.180).

758

CHAPTER 10  Lower Extremity

Quadriceps tendon

Popliteal artery

Vastus medialis muscle

A

Femur

Vastus lateralis muscle R

L Greater saphenous vein

Biceps femoris muscle

Sartorius muscle

Common peroneal nerve

Popliteal vein

Gracilis tendon

Tibial nerve

Small saphenous vein

P

Semitendinosus tendon

Semimembranosus muscle

FIG. 10.177  Axial, T1-weighted MRI of right knee with vessels.

A Patella Medial patellar retinaculum

Medial femoral condyle

Popliteal artery R

L Greater saphenous vein Sartorius muscle Gracilis tendon

Semimembranosus tendon Gastrocnemius muscle (lateral head)

Tibial nerve

P

Gastrocnemius muscle (medial head)

Semitendinosus tendon

FIG. 10.178  Axial, T1-weighted MRI of right knee with vessels.

CHAPTER 10  Lower Extremity S

Common iliac artery

Inferior vena cava

759

Inferior vena cava S

Aorta

Common iliac artery

Common iliac vein

External iliac artery

Internal iliac vein External iliac vein Inguinal ligament Profunda femoris vein

L

R Femoral vein

Great saphenous vein

Femoral vein

Common iliac vein

External iliac vein

Internal iliac artery

Profunda femoris artery R

L

Great saphenous vein

Femoral artery Great saphenous vein

Popliteal vein

Popliteal vein

I

Anterior tibial vein Fibular (peroneal) vein

Fibular (peroneal) vein

Anterior tibial vein

Small saphenous vein

FIG. 10.180  Anterior view of femoral artery and vein and great saphenous vein.

Posterior tibial vein

Dorsalis pedis vein

Dorsal venous arch

Plantar veins Plantar arch

Metatarsal veins

Digital veins I

FIG. 10.179  Veins of the leg. Left, Anterior view. Right, Posterior view.

Nerves The nerves of the lower extremity are derived from the lumbar and sacral plexuses (see Chapter 4). The femoral nerve enters the thigh beneath the inguinal ligament and divides into several superficial and deep branches to supply the anterior compartment of the thigh. The femoral nerve terminates as the saphenous nerve to innervate the skin on the medial side of the leg and foot. The obturator nerve courses through the obturator canal and immediately

divides into anterior and posterior divisions to supply the medial compartment of the thigh. The sciatic nerve is the largest peripheral nerve in the body. Its branches supply the posterior compartment of the thigh and all compartments of the distal leg and foot. The sciatic nerve runs deep to the gluteus maximus muscle and descends in the midline of the thigh, where it usually divides into two terminal branches: the tibial (medial popliteal) and common peroneal (lateral popliteal) nerves (Figs. 10.40–10.45, 10.102–10.109, 10.170, 10.177, 10.178, and 10.181).

760

CHAPTER 10  Lower Extremity S 1 2 3 4

Lumbar plexus T-12, L - 1, 2, 3, 4 Lateral cutaneous nerve of thigh, L - 2, 3

5

Obturator nerve L - 2, 3, 4

Sacral plexus

Sacral plexus L - 4, 5, S - 1, 2, 3

Pudendal nerve S - 2, 3, 4 Sciatic nerve L - 4, 5 S - 1, 2, 3 Femoral nerve L - 2, 3, 4

L

R

Tibial nerve (medial popliteal) Common peroneal (lateral popliteal) nerve

Sural nerve Common peroneal nerve

Posterior tibial nerve Superficial peroneal nerve

Saphenous nerve

Deep peroneal nerve Saphenous nerve

Sural nerve

Musculocutaneous part of superficial peroneal nerve

Sural nerve

Deep peroneal nerve

I

FIG. 10.181  Anterior and posterior views of right leg and foot with nerves.

REFERENCES Anderson, M. W., & Fox, M. G. (2017). Sectional anatomy by MRI and CT (4th ed.). Philadelphia: Elsevier. Frank, G. (2012). Merrill’s atlas of radiographic positions and radiologic procedures (12th ed.). St. Louis: Mosby. Haaga, J. R., & Boll, D. T. (2017). CT and MRI of the whole body (6th ed.). Philadelphia: Elsevier. Manaster, B. J. (2016). Diagnostic imaging: Musculoskeletal: Nontraumatic disease (2nd ed.). Philadelphia: Elsevier. Manaster, B. J., & Crim, J. (2016). Imaging anatomy: Musculoskeletal (2nd ed.). Philadelphia: Elsevier.

Miller, M. D., & Cooper, D. E. (2002). Review of sports medicine and arthroscopy (2nd ed.). Philadelphia: Elsevier. Palastanga, N. (2002). Anatomy and human movement: Structure and function (4th ed.). Boston: Butterworth-Heinemann. Seidel, H. M., Ball, J. W., Dains, J. E., et al. (2010). Mosby’s guide to physical examination (7th ed.). St. Louis: Mosby. Standring, S. (2012). Gray’s anatomy, the anatomical basis of clinical practice (41st ed.). New York: Elsevier. Weir, J., & Abrahams, P. H. (2011). Imaging atlas of human anatomy (4th ed.). London: Elsevier.

Illustration Credits CHAPTER 1 Figure 1.7 from Jacob S: Atlas of human anatomy, Philadelphia, 2002, Churchill Livingstone. Figure 1.10 from Seeram E: Computed tomography: Physical principles, clinical applications, and quality control, ed 3, St. Louis, 2009, Saunders. Figure 1.11 from Mitchell DG: MRI principles, ed 2, Philadelphia, 2004, Saunders. Figure 1.14 from Stark DD, Bradley WG: Magnetic resonance imaging, ed 3, St. Louis, 1999, Mosby.

CHAPTER 2 Figures 2.2, 2.3, 2.18, 2.20, 2.67, 2.68, 2.81 from Frank ed: Merrill’s atlas of positioning and radiographic procedures, ed 12, St. Louis, 2012, Mosby. Figure 2.24 from Mosby’s dictionary of medical and health professions, ed 8, St. Louis, 2009, Mosby. Figure 2.47 from Runge MS, Greganti MA: Netter’s internal medicine, ed 2, St. Louis, 2008, Saunders. Figures 2.88, 2.90 from Tamimi, D, Hatcher DC: Specialty imaging: Temporomandibular joint, ed 1, St Louis, 2016, Elsevier. Figures 2.70, 2.76, 2.80, 2.107, 2.110 from Som PM, Curtin HD: Head and neck imaging, ed 5, St. Louis, 2011, Mosby.

CHAPTER 3 Figure 3.17 from Applegate E: The sectional anatomy learning system, ed 3, St. Louis, 2010, Saunders. Figures 3.60, 3.73, 3.112, 3.113, 3.118, 3.119, 3.134 from Fitzgerald MJT: Clinical neuroanatomy and related neuroscience, ed 6, Philadelphia, 2012, Saunders. Figures 3.84, 3.104 from Standring S: Gray’s anatomy, ed 40, Philadelphia, 2009, Churchill Livingstone. Figure 3.94 from Noback CR, Demarest RJ: The nervous system: Introduction and review, New York, 1972, McGraw-Hill. Figure 3.103 from Langley LL, Christensen JB, Telford IR, et al: Dynamic anatomy and physiology, ed 4, New York, 1974, McGraw Hill. Copyright Mosby-Year Book, Inc. Figure 3.115 from Weir J: Imaging atlas of human anatomy, ed 4, Philadelphia, 2011, Mosby. Figure 3.130 from Jacob S: Atlas of human anatomy, Philadelphia, 2002, Churchill Livingstone.

CHAPTER 4 Figure 4.7 from Frank ED: Merrill’s atlas of positioning and radiographic procedures, ed 12, St. Louis, 2012, Mosby. Figure 4.65B from Larsen WL: Anatomy development, function, clinical correlations, Philadelphia, 2002, Saunders. Figure 4.69 from Mosby’s dictionary of medical and health professions, ed 8, St. Louis, 2009, Mosby. Figure 4.70 from Jacob S: Atlas of human anatomy, Philadelphia, 2002, Churchill Livingstone. Figure 4.76 from Weir J: Imaging atlas of human anatomy, ed 4, Philadelphia, 2011, Mosby. Figure 4.88 from Standring S: Gray’s anatomy, ed 40, Philadelphia, 2009, Churchill Livingstone. Figures 4.101, 4.102, 4.106 from Palastanga N, Field D, Soames R, et al: Anatomy and human movement, ed 4, Boston, 2002, Butterworth-Heinemann. Figure 4.116 from Stark DD, Bradley WG: Magnetic resonance imaging, ed 3, St. Louis, 1999, Mosby.

Figure 4.125 Netter illustration used with permission from Icon Learning Systems, a division of MediMedia USA, Inc. All rights reserved.

CHAPTER 5 Figure 5.19 from Mosby’s dictionary of medical and health professions, ed 8, St. Louis, 2009, Mosby. Figures 5.49, 5.51, 5.52, 5.53, 5.54, 5.55 from Som PM, Curtin HD: Head and neck imaging, ed 5, St. Louis, 2011, Mosby. Figure 5.70 from Standring S: Gray’s anatomy: The anatomical basis of clinical practice, ed 41, Philadelphia, 2016, Elsevier Limited. Figures 5.77, 5.78 from Standring S: Gray’s anatomy, ed 40, Philadelphia, 2009, Churchill Livingstone. Figure 5.81 from Curry RA, Tempkin BB: Sonography: Introduction to normal structure and function, ed 3, St. Louis, 2011, Saunders.

CHAPTER 6 Figure 6.3 courtesy of Anne Marie Sawyer, Radiologic Sciences Laboratory, Stanford University School of Medicine, Stanford, Calif. Figures 6.15, 6.87, 6.90 from Standring S: Gray’s anatomy, ed 40, Philadelphia, 2009, Churchill Livingstone. Figures 6.21, 6.148 from Palastanga N, Field D, Soames R, et al: Anatomy and human movement, ed 4, Boston, 2002, ButterworthHeinemann. Figure 6.27 from Haaga JR, Lanzieri CF, Gilkeson RC, et al: CT and MR imaging of the whole body, ed 5, Philadelphia, 2009, Mosby. Figure 6.32 from Grainger & Allison’s diagnostic radiology: Expert consult, ed 6, vol 1; Philadelphia, 2014, Churchill Livingstone. Figure 15.24 B. Figures 6.34, 6.157 from Seidel HM, Ball JW, Dains JE, et al: Mosby’s guide to physical examination, ed 7, St. Louis, 2011, Mosby. Figures 6.39, 6.65, 6.83, 6.85, 6.93, 6.114 from Weir: Imaging atlas of human anatomy, ed 4, Philadelphia, 2011, Mosby. Figures 6.41, 6.48, 6.126, 6.131 from Manning WJ, Pennell DJ: Cardiovascular magnetic resonance, Philadelphia, 2011, Churchill Livingstone. Figure 6.44 from Applegate E: The sectional anatomy learning system, ed 3, St. Louis, 2010, Saunders. Figures 6.64, 6.70, 6.77, 6.88, 6.91 from Anderson M, Fox M: Sectional anatomy by MRI and CT, ed 4, St. Louis, 2016, Elsevier. Figure 6.75 from Wilson SF, Thompson JM: Respiratory disorders, St. Louis, 1990, Mosby. Figure 6.140 from Jacob: Atlas of human anatomy, Philadelphia, 2002, Churchill Livingstone. Figures 6.145, 6.146 from Larsen WL: Anatomy development, function, clinical correlations, Philadelphia, 2002, Saunders. Figure 6.158 from Mosby’s dictionary of medical and health professions, ed 8, St. Louis, 2009, Mosby.

CHAPTER 7 Figure 7.6 from Larsen WL: Anatomy development, function, clinical correlations, Philadelphia, 2002, Saunders. Figures 7.8, 7.9, 7.13, 7.16, 7.40, 7.43, 7.46, 7.49 from Haaga JR, Lanzieri CF, Gilkeson RC, et al: CT and MR imaging of the whole body, ed 5, Philadelphia, 2009, Mosby. Figures 7.12, 7.173 from Standring S: Gray’s anatomy, ed 40, Philadelphia, 2009, Churchill Livingstone. Figures 7.27, 7.28, 7.63, 7.80, 7.87, 7.151, 7.158, 7.166, 7.169, 7.181 from Hagen-Ansert SL: Textbook of diagnostic sonography, ed 7, St. Louis, 2012, Mosby.

Copyright © 2019, Elsevier Inc.

761

762

Illustration Credits

Figures 7.39, 7.42, 7.45, 7.48, 7.102 from Stark DD, Bradley WG: Magnetic resonance imaging, ed 3, St. Louis, 1999, Mosby. Figures 7.142, 7.167 from Torigian D, Hammell MK: Netter’s correlative imaging: Abdominal and pelvic anatomy, Philadephia, 2012, Saunders. Figures 7.179, 7.180 from Webb WR, Brant WE, Major N: Fundamentals of body CT, ed 3, Philadelphia, 2006, Saunders.

CHAPTER 8 Figures 8.9, 8.11 from Frank ED: Merrill’s atlas of positioning and radiographic procedures, ed 12, St. Louis, 2012, Mosby. Figure 8.18 from Larsen WL: Anatomy development, function, clinical correlations, Philadelphia, 2002, Saunders. Figures 8.43, 8.45, 8.58, 8.79, 8.83, 8.101 from Applegate E: The sectional anatomy learning system, ed. 3, St. Louis, 2010, Saunders. Figures 8.54, 8.123 from Seidel HM, Ball JW, Dains JE, et al: Mosby’s guide to physical examination, ed 7, St. Louis, 2011, Mosby. Figures 8.65, 8.121 from Hagen-Ansert: Textbook of diagnostic sonography, ed 8, St. Louis, 2018, Mosby. Figure 8.85 from Haaga JR, Lanzieri CF, Gilkeson RC, et al: CT and MR imaging of the whole body, ed 5, Philadelphia, 2009, Mosby. Figures 8.96, 8.100 courtesy of GE Medical Systems, Milwaukee, Wisc.

CHAPTER 9 Figures 9.20, 9.21, 9.22 from Spratt JD, Salkowski LR, Loukas M, et al: Weir & Abrahams’ imaging atlas of human anatomy, ed 5, Philadelphia, 2017, Elsevier Limited. Figure 9.36 from Seidel HM, Ball JW, Dains JE, et al: Mosby’s guide to physical examination, ed 7, St. Louis, 2011, Mosby. Figures 9.51, 9.52 from Weir J: Imaging atlas of human anatomy, ed 4, Philadelphia, 2011, Mosby. Figures 9.87, 9.127 from Miller MD, Cooper DE: Review of sports medicine and arthroscopy, ed 2, Philadelphia, 2002, Saunders. Figure 9.124 from Palastanga N, Field D, Soames R, et al: Anatomy and human movement, ed 4, Boston, 2002, Butterworth-Heinemann. Figures 9.126, 9.142 from Kang HS, Ahn JM: MRI of the extremities, ed 2, Philadelphia, 2002, Saunders.

CHAPTER 10 Figure 10.12 from Byrd JWT: Operative hip arthroscopy, New York, Thieme, 1998, Thieme, p. 78. Figures 10.168, 10.174 from Standring S: Gray’s anatomy, ed 40, Philadelphia, 2009, Churchill Livingstone.

Index A Abdomen, 4, 6f, 7t, 399–496, 399f Abdominal aorta, 351–352, 358f, 359f, 471–486, 471f, 472f, 473f, 483f, 488f, 555f, 561f, 562f, 563f, 752f paired branches of, 473–476 unpaired branches of, 477–486 Abdominal cavity, 400–412, 400f Abdominal lymph nodes, 491 Abdominal wall, 452f, 492–494 Abdominopelvic cavity, 4, 5f, 6t Abducens nerve, 119f, 150f, 152f, 156f, 156t, 160f, 161f, 162f, 165, 165f Abductor digiti minimi muscle, 646, 647f, 649f, 748, 749f, 750f Abductor hallucis muscle, 748, 749f Abductor pollicis brevis muscle, 637f, 645, 647f, 649f Abductor pollicis longus muscle, 605f, 616t, 617f, 619f, 625f, 626 Acanthion, 4f, 49f Accessory hemiazygos vein, 388f Accessory nerve, 119f, 156f, 156t, 169f, 170, 170f Acetabular fat, 669f Acetabular fossa, 660, 660f, 661f, 665f, 669f Acetabular labrum, 661f, 665, 665f Acetabular ligament, 671f Acetabular notch, 660, 660f Acetabulum, 240f, 498f, 499f, 502f, 503f, 504f, 505f, 512f, 514f, 538f, 560f, 660, 660f, 662f, 668f, 669f, 671f Achilles tendon, 692f, 716, 747 Acinus, 323f Acromial end, of clavicle, 569f Acromioclavicular joint, 569–570, 569f, 570f, 571f, 579f, 584f, 585f, 595f, 597f Acromioclavicular ligament, 576–577, 576f, 577f, 578f, 579f, 595f Acromion, 569f, 570f, 571f, 572f, 573f, 575f, 576f, 577f, 578f, 579f, 580f, 584f, 586f, 588f, 593f, 595f, 596f, 597f, 599f, 604f, 605f Acute pancreatitis, 439b Adductor brevis muscle, 504f, 678f, 680f, 686 Adductor hallucis muscle, 750 Adductor hallucis oblique head, 750f Adductor longus muscle, 510f, 677f, 678f, 680f, 681f, 682f, 686 Adductor magnus muscle, 239f, 510f, 673f, 674f, 677f, 678f, 679f, 680f, 681f, 682f, 686 Adductor minimus muscle, 510f, 648f Adductor pollicis muscle, 646, 647f, 648f, 649f Adductor tubercle, 687 Adenohypophysis, 112 Adipose tissue, 397f Aditus ad antrum mastoideum, 37, 39f Adrenal cortex, 444–445, 444f Adrenal gland, 444–445, 444f, 445f, 446f, 447f, 449f, 473f Adrenal medulla, 444–445, 444f Air, in stomach, 459f, 469f Ala of ilium, 498f, 499f, 500f, 502f, 504f Alar fold, 694f Alar ligaments, 194, 196f

Alveolar process, 49f, 50–53, 51f, 52f, 53f, 54f, 57, 57f, 75f Alveoli, 323f, 397f Ambient cistern, 96–97, 97f, 98f, 116f, 117f, 144f, 161f, 162f Ampulla, 37f, 527f Ampulla of Vater, 433–436, 433f, 434f, 439, 442f, 461f Amygdala, 107f, 108f, 114, 115f, 116b, 116f, 117f Anal canal, 464f, 527, 527f Anal triangle, 515f, 518, 518f, 519f Anatomic neck, 573, 575f, 606f Anatomic planes, 2 Anatomic positions, 2, 2f Anconeus muscle, 605, 605f, 605t, 608f, 611f, 614f, 615f, 619f, 620f, 621f, 625f Angular notch, 455f Ankle, 719–750 bony anatomy of, 719–726, 725f, 726f, 730f, 733f, 734f, 737f, 738f, 739f, 740f fascia of, 734 ligaments of, 734–735, 740f, 741f, 742f retinacula of, 734 tendons of, 740f, 741f, 742f, 747–748 Annulus fibrosus, 177f, 178f, 191f, 198f Anterior, 3t Anterior abdominal wall, 435f Anterior acetabular labrum, 668f, 669f, 671f Anterior arch, 179f, 181f, 194f, 195f Anterior atlantooccipital membrane, 194, 194f, 195f Anterior basal segmental bronchus, 321f, 322f Anterior cardiac veins, 351f, 375, 379f Anterior central artery, 244f Anterior central vein, 246, 246f Anterior cerebral artery, 113f, 130, 131f, 131t, 132f, 133f, 134f, 134t, 135f, 136f, 137f, 139f, 141f, 143f, 144f, 145f, 148f, 155f, 306f, 307f Anterior cerebral vein, 146f, 155f Anterior choroidal artery, 141f Anterior clinoid process, 17f, 20f, 21f, 23–25, 23f, 24f, 26f, 58f, 70f, 75f, 76f Anterior column, 661f, 669f, 671f Anterior commissure, 95f, 100, 102f, 104f, 111f, 113f, 114f, 115f Anterior communicating artery, 130, 135f, 136f, 141f, 143f, 144f, 145f Anterior compartment, of mediastinum, 324, 324t Anterior cranial fossa, 14–18, 16f, 18t Anterior crest, 690f Anterior cruciate ligament, 688f, 690f, 694f, 695f, 696f, 700, 704f Anterior ethmoid air cell, 21f, 56f, 67f Anterior ethmoid sinuses, 55f, 66f Anterior external venous plexuses, 246, 246f, 247f Anterior facial vein, 286f, 289f Anterior fat pad, 609f, 610f, 612f Anterior fontanel, 47, 47b, 47f Anterior fornix, 516f, 529f Anterior glenoid labrum, 592f Anterior inferior cerebellar artery, 131f, 133f, 138, 139f, 141f, 142f, 145f, 145t, 242f Anterior inferior iliac spine, 502f, 503f, 664f, 665f Copyright © 2019, Elsevier Inc.

Anterior interior pancreatic duodenal artery, 439f, 481f Anterior internal venous plexus, 246f, 247f Anterior interosseous artery, 651–655, 652f, 654f Anterior interosseous vein, 654f Anterior interventricular artery, 352f Anterior interventricular groove, 339f, 345f, 351f Anterior jugular nodal chain, 280f Anterior jugular vein, 263f, 266f, 290f, 291f, 292f, 293f, 308f Anterior left subphrenic space, 403f, 406f Anterior lobe, 112f Anterior longitudinal ligament, 178f, 191f, 194–196, 194f, 195f, 198f, 199f, 200f, 201f, 253f, 262f Anterior median fissure, 119f, 125, 125f, 126f, 170f, 213f, 214, 223f, 242f, 246f Anterior median vein, 246, 246f Anterior mediastinum, 324f Anterior meniscofemoral ligament, 695 Anterior nasal spine, 49f, 50–53, 51f, 75f Anterior pararenal space, 412, 412f, 413f Anterior pericardium, 324f Anterior radicular artery, 241, 244f Anterior radicular vein, 246, 246f Anterior renal (Gerota’s) fascia, 410f, 412f Anterior scalene muscle, 233f, 234f, 235f, 236f, 270f, 281f, 285f, 292f, 293f, 299f, 300–301, 300t Anterior scutum, 43f Anterior segment, of right lobe, 420f Anterior segmental bronchus, 320f, 321f, 322f Anterior segmental medullary arteries, 242f Anterior spinal artery, 139f, 141f, 145f, 241, 242f, 243f, 244f Anterior subphrenic space, 403f Anterior superior iliac spine, 208f, 493f, 495f, 499f, 502f, 503f, 510f, 662f, 664f Anterior superior pancreatic duodenal artery, 439f, 477f, 481f Anterior talofibular ligament, 692f Anterior thalamic nuclei, 115f Anterior tibial artery, 753, 756f, 757f Anterior tibial recurrent artery, 756f Anterior tibial vein, 759f Anterior triangle muscles, 298, 299f, 300t Anterior ulnar recurrent artery, 651, 652f Anterior venous plexus, 248f Anterolateral fontanel, 47, 48f Antrum of Highmore, 69 Anular ligament, 612, 612f, 614f, 615f, 637f Anular pulleys, 641, 641f Anus, 467f, 515f, 518f, 520f, 522f, 529f Aorta, 139f, 216f, 244f, 245f, 269f, 318f, 324f, 339f, 348f, 349f, 351–352, 356f, 363f, 373f, 387f, 394f, 395f, 400f, 401f, 402f, 403f, 405f, 407f, 412f, 413f, 416f, 419f, 420f, 421f, 422f, 423f, 425f, 428f, 429f, 430f, 431f, 436f, 437f, 438f, 439f, 441f, 442f, 444f, 446f, 447f, 448f, 453f, 457f, 462f, 468f, 469f, 472f, 473f, 474f, 475f, 476f, 477f, 478f, 479f, 481f, 482f, 483f, 484f, 485f, 486f, 487f, 490f, 492f, 493f, 557f, 566f, 756f terminal segment of, 471f

763

764

INDEX

Aortic arch, 139f, 277f, 303f, 304f, 305f, 306f, 307f, 314f, 324f, 325f, 326f, 328f, 339f, 346f, 347f, 351f, 352f, 354f, 355f, 356f, 358f, 359f, 365f, 366f, 368f, 370f, 394f branches of, 365, 365f, 366f, 367f, 368f Aortic hiatus, 391–392, 394f Aortic root, 351f, 353f, 355f, 374f, 386f Aortic semilunar valve, 312f, 333f, 342f, 346f, 348, 348f, 349f, 350f, 362f, 372f, 383f, 387f Aortic sinuses, 351–352 Aortic valve, 361f Aorto-caval nodes, 491f Apex, 691f of bladder, 520f, 523f Apical ligament, 194, 194f, 195f Apical segmental bronchus, 320f, 322f Apical segmental veins, 474f Aponeurosis, of oblique muscles, 493f Appendicular artery, 485f Appendix, 404f, 415f, 485f Aqueduct of Sylvius, 87–91, 90f Aqueous humor, 77, 77f, 78f Arachnoid granulation, 87f, 95f Arachnoid mater, 210–212, 213f, 221f, 223f Arachnoid membrane, 87–91, 87f Arachnoid villi, 87f, 91 Arcuate artery, 474f, 756f Arcuate line, 498f, 499f, 503f, 506f Arcuate popliteal ligament, 690f, 697f, 700, 701f Arcuate veins, 474f, 490 Arnold-Chiari malformation, 127b Arterial arcades, 485f Arteriovenous malformations, 138b Artery of Adamkiewicz, 241, 241b, 242f, 243f Articular cartilage, 669f, 670f, 671f Articular disk, 60f, 61, 61f, 62f Articular eminence, 30–32, 30f, 32f, 60, 60f, 61f Articular joint capsule, 585–586, 585f Articular process, 175f, 193f Articular surface, 665f Aryepiglottic fold, 252f, 257f, 258f, 260f, 261–264, 263f, 268f Arytenoid cartilage, 257f, 258f, 259f, 261–264, 261f, 262f, 263f, 266f, 268f, 278f, 291f, 297f Ascending aorta, 311f, 317f, 319f, 320f, 321f, 326f, 330f, 334f, 337f, 339f, 340f, 341f, 346f, 347f, 350f, 351–352, 351f, 352f, 355f, 356f, 357f, 358f, 360f, 361f, 362f, 364f, 365f, 366f, 369f, 370f, 371f, 372f, 373f, 374f, 375f, 383f, 385f, 387f Ascending branch, of ileocolic artery, 485f Ascending cervical artery, 242f, 304f Ascending colon, 408f, 411f, 415f, 419f, 424f, 437f, 453f, 460f, 461f, 462f, 463f, 464–465, 464f, 466f, 467f, 485f, 496f Ascending general sensory tracts, 120f Ascending lumbar vein, 388f, 488 Ascending pharyngeal artery, 286f, 304f Asterion, 14f, 15f, 18f, 44–46, 44f Atlantoaxial joint, 180f, 181f, 182f Atlantooccipital joint, 27f, 28f, 180f, 181f, 182f, 194f, 195f Atlantooccipital membrane, 194 Atlas, 179f, 181f Atria, 338 Atrioventricular bundle, 338f, 339, 349f Atrioventricular groove, 338, 339f Atrioventricular node, 338f, 339 Atrioventricular valves, 348 Attic, 37 Auditory ossicles, 35–37, 35f, 40f, 166f

Auditory tube, 30f, 33f, 35–37, 35f, 166f, 251, 251f, 252f, 284f Auricle, 31f, 35, 35f, 166f, 271f Autism, gray matter and, 105b Avascular necrosis, 661b Axial (transverse) plane, 2, 2f Axillary artery, 593f, 597f, 650–651f, 651, 652f, 654f Axillary nerve, 232f, 593f, 604f, 657f Axillary recess, 579f, 582f, 584f, 585–586, 585f Axillary vein, 588f, 593f, 597f, 654f, 655, 656f Axis, 180f, 181f, 182f Azygos arch, 389f Azygos vein, 231f, 318f, 319f, 332f, 340f, 342f, 352f, 357f, 360f, 362f, 376f, 377f, 378f, 379f, 388, 388f, 389f, 390f Azygos venous system, 388, 388f, 389f, 390f

B Bare area, of liver, 402f, 409f, 414f Bartholin’s duct, 271 Basal cisterns, 97f Basal lamella, 56f, 67 Basal nuclei, 106, 106b, 107f, 108f, 109f, 110f disease, 106b Basal vein of Rosenthal, 146f, 153, 153f, 154f, 155f Base, 691f of bladder, 520f Basilar artery, 94f, 98f, 99f, 114f, 123f, 124f, 131f, 132f, 133f, 134f, 135f, 137f, 139f, 140f, 141f, 142f, 143f, 144f, 145f, 161f, 162f, 165f, 167f, 242f, 306f, 307f branches of, 145t Basilar skull fracture, 32b Basilic artery, 601f Basilic vein, 600f, 601f, 603f, 604f, 619f, 621f, 655, 656f Basivertebral veins, 217f, 246, 246f, 247f, 248f, 249f Bell’s palsy, 165b Biceps brachii muscle, 585f, 599f, 600f, 601f, 602f, 603f, 604f, 605t, 608f, 614f, 615f, 622f Biceps brachii tendon, 574f, 575f, 576f, 577f, 579f, 580f, 581f, 582f, 583f, 584f, 585f, 586f, 592f, 594f, 597f, 604f, 609f, 611f, 622f Biceps femoris muscle, 239f, 673f, 674f, 678f, 679f, 680f, 682f, 687, 688f, 703f, 758f Bicipital aponeurosis, 599–600 Bicipital groove, 569f, 572f, 573, 599–600 Bicuspid valve, 312f, 333f, 336f, 338f, 341f, 343f, 348, 348f, 349f, 376f, 380f, 381f, 382f, 383f, 387f Bifid spinous process, 182f, 183f Bile, 433–436 Bile duct, 400f, 443f Biliary system, 433–436, 433f, 434f Bladder, 240f, 448f, 454f, 470f Blood-brain barrier, 130 Blowout fracture, 77b Body of corpus callosum, 99, 102f, 103f of gallbladder, 433–436, 433f, 434f of ilium, 504f of mandible, 57, 57f of pancreas, 419f, 425f, 433f, 437f, 439f, 441f, 442f, 458f, 481f, 483f of pubis, 505f, 526f of sternum, 311f, 312f, 341f of stomach, 456f, 458f air in, 458f, 459f of uterus, 529f, 530f

Body cavities, 4, 5f, 6t Bony labyrinth, 35f, 38–44, 166f Bony orbit, 73, 74f Bony pelvis, 498–506, 498f, 499f coccyx, 498–500, 499f, 500f, 501f pelvic inlet and outlet, 506, 506f, 507f sacrum, 498–500, 499f, 500f, 501f Bony thorax, 310, 311f, 312f, 313f Brachial artery, 594f, 600f, 601f, 602f, 603f, 620f, 622f, 650–651f, 651, 652f Brachial plexus, 210f, 234f, 273f, 578f, 579f, 593f, 595f, 597f, 656–658, 657f Brachial veins, 601f, 602f, 603f, 655, 656f Brachialis muscle, 599f, 600, 600f, 601f, 602f, 603f, 604f, 605t, 609f, 610f, 611f, 612f, 613f, 614f, 615f, 622f, 623f Brachialis tendon, 609f, 611f Brachiocephalic artery, 139f, 325f, 358f Brachiocephalic trunk, 139f, 277f, 278f, 303f, 304f, 305f, 306f, 307f, 327f, 348f, 351f, 352f, 362f, 365, 365f, 366f, 367f, 368f, 370f Brachiocephalic vein, 303f, 308, 308f, 368, 656f Brachioradialis muscle, 600f, 602f, 603f, 611f, 614f, 615f, 616t, 617f, 621f, 622f, 623f, 625, 654f Brain, 86–171 axial magnetic resonance imaging of, 86f functions of, 86 meninges of, 87, 87f, 88f, 89f Brainstem, 119–125, 119f, 120f Breast, 397, 397f, 398f Bregma, 14f, 47, 47f, 48f Broad ligament, 530f, 532f, 533f, 535f, 537f, 539 Broca’s area, 100–105, 100f, 105f Bronchi, 269f, 320, 320f, 321f, 322f, 323f, 323t, 325f Bronchioles, 320 Bronchomediastinal trunk, 331f Bronchopulmonary segments, 320, 322f, 323t Bronchus intermedius, 322f Buccal nodes, 280f Buccinator muscle, 64f, 287f, 288f, 295f, 298f, 299f, 301f Bulbospongiosus muscle, 518f, 522f Bulbourethral glands (Cowper’s glands), 522f, 540f, 552 Bundle of His, 338f, 339

C C1, 179f, 181f, 182f, 184f, 196f, 197f, 202f, 225f, 230f, 262f, 273f, 284f, 301f, 304f C2, 180f, 181f, 182f, 184f, 196f, 197f, 254f, 273f C3, 181f, 182f, 184f C4, 182f, 184f, 285f C5, 184f C6, 184f C7, 183f, 184f, 285f Calcaneal tuberosity, 719–721, 749f Calcaneocuboid joint, 727 Calcaneus, 692f, 719–721, 721f, 722f, 723f, 724f, 729f, 730f Calcarine artery, 133f Callosomarginal artery, 130, 133f Calvaria, 147f Capitate bone, 626, 627f, 628f, 629f, 630f, 631f, 633f, 640f, 644f, 649f Capitellum, 606f, 607f, 608f Capitulum, 574f Cardia, 455f Cardiac antrum, 455f

INDEX Cardiac conduction system, 338f, 339 Cardiac imaging, off-axis, 380–382, 380f, 381f, 382f, 383f, 384f, 385f, 386f, 387f Cardiac impression, 318f, 362f, 363f Cardiac notch, 315f, 318f, 363f, 455f Cardiac orifice, 269f, 455 Cardiac sphincter, 269, 269f, 455 gastroesophageal junction, 455f Cardiac valves, 348, 348f, 349f, 350f Cardiac veins, 375, 379f Cardiophrenic sulcus, 315, 315f, 316f Carina, 269, 269f, 315f, 320, 320f, 321f, 322f, 326f, 328f, 330f, 355f, 392f Carotid arteries, see also Common carotid artery 302. Carotid bifurcation, 305f, 307f Carotid body, 168, 302, 304f tumors, 302b Carotid canal, 16f, 25f, 30–32, 30f, 31f, 32f, 33f, 34f, 40f, 43f Carotid sheath, 283f, 285f Carotid sinus, 168, 168f, 302, 304f, 306f, 307f Carotid siphon, 130, 131f, 134f, 135f, 136f, 307f Carotid space, 285f, 290f, 293t Carotid sulcus, 23f Carpal articular surface, 607f Carpal bones, 626, 627f, 629f, 630f, 631f, 633f, 640f, 649f Carpal tunnel, 635–636, 636f Carpal tunnel syndrome, 636b Carpometacarpal joint, 627f, 628f, 631f, 633 Cartilage, 35f Cauda equina, 177f, 178f, 191f, 201f, 210f, 211f, 212–214, 212f, 215f, 217f, 220f, 222f, 223f, 247f, 248f, 249f Caudal, 3t Caudal pancreatic branch, 481f Caudate lobe, of liver, 406f, 407f, 414f, 415, 415f, 416f, 417f, 421f, 422f, 428f, 430f Caudate nucleus, 101f, 106, 107f, 108f, 109f, 110f, 113f, 132f, 153f, 159f Caval hiatus, 391–392, 394f, 432f, 488f Cavernous sinus, 88f, 132f, 146f, 150f, 151f, 152f, 153, 161f, 162f CBD. see Common bile duct Cecal artery, 485f Cecum, 404f, 460f, 461f, 463f, 464–465, 464f, 465f, 466f, 467f Celiac axis, 439f, 481f, 485f Celiac nodes, 491f Celiac trunk, 245f, 428f, 429f, 430f, 437f, 444f, 447f, 471f, 472f, 473f, 475f, 477–481, 477f, 478f, 479f, 480f, 481f, 482f, 483f, 485f, 487f, 488f, 555f, 561f, 563f Central canal, 90f, 95f, 111f, 120f, 213f, 214, 218f, 223f Central sulcus, 99, 100f Central tendon, 391–392, 394f, 493f Cephalic, 3t Cephalic vein, 597f, 600f, 601f, 603f, 619f, 621f, 655–656, 655f, 656f Cerebellar hemispheres, 97f, 127 Cerebellar peduncles, 127 Cerebellar tonsils, 112f, 127, 127f, 128f, 160f Cerebellopontine angle (CPA) cistern, 36f, 96–97, 98f, 99f, 129f, 165f Cerebellum, 29f, 37f, 88f, 89f, 93f, 94f, 95f, 96f, 98f, 99f, 100f, 107f, 112f, 117f, 121f, 122f, 123f, 124f, 125f, 126f, 127, 127f, 128f, 129f, 130f, 139f, 150f, 154f, 163f, 165f, 167f, 169f, 170f

Cerebral aqueduct, 87–91, 90f, 93f, 95f, 97f, 102f, 111f, 112f, 117f, 119f, 120f, 121f, 126f, 136f, 161f Cerebral cortex, 87f, 99, 101f, 103f, 104f radiations to, 120f Cerebral hemispheres, 99 Cerebral peduncle, 97f, 98f, 112f, 116f, 119f, 120–123, 120f, 121f, 122f, 124f, 126f, 128f, 136f, 137f, 161f, 162f, 167f Cerebral vascular system, 130–153 arterial supply, 130–138 anterior cerebral artery, 113f, 130, 131f, 131t, 132f, 133f, 134f, 134t, 135f, 136f, 137f, 139f, 143f, 144f, 145f circle of Willis and, 138, 144f, 145f pathology involving, 138b venous drainage in, 146–153, 146f deep veins in, 153, 153f dural sinuses in, 146–153, 150f superficial cortical veins in, 153, 153f Cerebrospinal fluid, 184f Cerebrum, 89f, 99–106 coronal view, 101f gray matter, 99–100 lobes of, 100–105, 105f, 106f, 107f white matter, 99–100 Cervical canal, 530f Cervical ligaments, 532 Cervical lymphadenopathy, 250f Cervical nerves, 223f Cervical spinal cord, 213f, 214f, 225f, 248f Cervical vertebrae, 173f, 179–180, 180f, 181f, 182f, 184f, 196f, 199f, 210f, 213f, 242f, 248f Cervix, 516f, 520f, 529–530, 529f, 530f, 533f, 534f, 539f, 566f CHD. see Common hepatic duct Chickenpox, 212b Cholesteatomas, 44b Chorda tympani, 166f Chordae tendinae, 338f, 348 Choroid plexus, 91, 92f, 95f, 111f, 119f calcified, 96f, 115f, 148f Choroidal vein, 146f, 153f, 155f Cingulate gyrus, 101f, 102f, 111f, 114, 115f, 117f, 118f Circle of Willis, 138, 144f, 145f Circumflex artery, 351f, 352f, 361f, 370–371, 370f, 371f, 372f, 374f Cisterna chyli, 331, 331f, 491f Cisterna magna, 93f, 94f, 95f, 96–97, 97f, 99f Cisterns, 91–97 Claustrum, 101f, 106, 108f, 109f, 110f, 132f Clavicle, 232f, 233f, 236f, 274f, 304f, 312f, 328f, 330f, 334f, 350f, 397f, 568f, 569– 570, 569f, 570f, 571f, 572f, 573f, 576f, 577f, 578f, 579f, 581f, 584f, 585f, 587f, 588f, 589f, 594f, 596f, 597f, 598f, 599f Clavicular head, 598f Clavicular notch, 569f Clitoris, 520f, 529f Clivus, 16f, 17f, 19f, 23f, 27–30, 27f, 28f, 29f, 33f, 36f, 45f, 50f, 59f, 125f, 169f, 171f, 194f, 195f, 196f, 251, 251f, 252f, 253f, 262f, 273f Coccygeal cornu, 173f Coccygeal nerve, 210f, 223f Coccygeus muscle, 208f, 513, 513f, 513t, 514f, 558f Coccyx, 173f, 187f, 191, 192f, 193f, 498– 500, 498f, 499f, 500f, 501f, 502f, 506f, 507f, 513f, 514f, 516f, 518f, 519f, 522f, 526f, 558f, 560f, 664f Cochlea, 31f, 35f, 36f, 37f, 39f, 40f, 42f, 43f, 166f, 167f Cochlear aqueduct, 37f

765

Cochlear duct, 37f Cochlear nerve, 31f Colic impression, 414f Collateral ligaments, 61, 612, 612f, 613f, 614f, 622f, 635–636, 644f, 700, 702f, 708f Collecting duct, 451f Collecting tubules, 448 Colon, 464–465 ascending, 408f, 411f, 415f descending, 408f, 412f, 415f, 424f, 450f, 460f, 464–465, 465f, 466f, 467f, 486f, 496f sigmoid, 404f, 464–465, 464f, 466f, 467f, 470f, 486f transverse, 402f, 408f, 415f, 435f, 436f, 460f, 461f, 462f, 464–465, 464f, 465f, 466f, 467f, 468f, 469f, 485f, 486f Common bile duct (CBD), 418f, 428f, 433–436, 433f, 434f, 435f, 436f, 437f, 438f, 440f, 441f Common carotid artery, 139f, 233f, 234f, 235f, 259f, 260f, 263f, 266f, 267f, 270f, 277f, 279f, 285f, 290f, 291f, 292f, 293f, 302, 302t, 303f, 304f, 305f, 306f, 307f Common extensor tendon, 611f Common flexor tendon, 611f Common hepatic artery, 428, 428f, 429f, 430f, 437f, 439f, 471f, 472f, 477f, 478f, 479f, 480, 480f, 481f, 485f, 486f, 487f, 555f, 561f Common hepatic duct (CHD), 414f, 428f, 433–436, 433f, 434f, 435f, 438f Common iliac artery, 488f, 557f, 563f, 566f, 752f, 756f, 759f Common iliac nodes, 491f, 566f Common iliac vein, 488f, 489f, 557f, 563f, 564f, 759f Common interosseous artery, 650–651f, 651 Common palmar digital artery, 653f Common peroneal nerve, 237f, 758f, 759, 760f Condyloid process, 57, 57f, 58f, 59f, 60f, 61f, 62f, 63f, 65f Confluence of sinuses, 88f, 146, 146f, 148f, 149f, 150f, 155f Constrictor muscles, 294 Contralateral, 3t Conus medullaris, 186f, 191f, 210f, 211f, 212–214, 212f, 215f, 216f, 218f, 223f, 226f, 227f, 247f Convoluted tubules, 448, 451f Cooper’s ligaments, 397, 397f Coracoacromial arch, 576f Coracoacromial ligament, 576–577, 576f, 577f, 579f, 580f, 584f, 586f, 594f, 597f Coracobrachialis bursa, 597f Coracobrachialis muscle, 577f, 578f, 581f, 583f, 584f, 592f, 593f, 595f, 597f, 599f, 600, 600f, 601f, 604f, 605t Coracoclavicular ligament, 572f, 576–577, 577f, 578f, 579f, 584f, 595f, 597f Coracohumeral ligament, 574f, 576–577, 577f, 578f, 579f, 580f, 581f, 584f, 586f, 591f, 594f, 595f Coracoid process, 569f, 570–572, 571f, 572f, 573f, 574f, 575f, 576f, 577f, 578f, 579f, 580f, 581f, 582f, 584f, 586f, 588f, 591f, 594f, 595f, 596f, 597f, 598f, 599f Cornea, 77 Corniculate cartilage, 252f, 261–264, 261f, 268f Cornua, 530f Coronal plane, 2, 2f Coronal suture, 14f, 15f, 17f, 18f, 44–46, 44f, 46f, 47f, 48f

766

INDEX

Coronary arteries, 370–371, 370f, 371f, 372f, 373f, 374f, 375f, 376f, 377f Coronary circulation, 370–375, 370b cardiac veins, 375, 379f coronary arteries in, 370–371, 370f, 371f, 372f, 373f, 374f, 375f, 376f, 377f Coronary groove, 339f, 344f, 351f, 352f, 379f Coronary ligaments, 402f, 404, 407f, 408t, 414f Coronary sinus, 342f, 344f, 352f, 375, 377f, 379f, 380f, 383f, 384f, 387f Coronoid fossa, 574f, 606f, 608, 611f Coronoid process, 28f, 49f, 57, 57f, 58f, 606f, 607f, 609, 609f, 610f, 611f, 622f, 623f Corpus callosum, 94f, 95f, 99, 101f, 102f, 103f, 104f, 110f, 113f, 115f, 117f, 118f, 124f, 153f, 155f Corpus cavernosum, 516f, 522f, 541f Corpus spongiosum, 516f, 522f, 541f Cortex of left kidney, 450f of right kidney, 450f Costal cartilages, 310, 310f, 312f, 341f, 495f, 598f Costal facet, 185f Costal surface, 315f, 414f Costocervical trunk, 304f, 650–651f Costodiaphragmatic recesses, 314, 314f Costomediastinal recesses, 314, 314f Costophrenic sulcus, 315, 315f, 316f Costotransverse joints, 185f, 310, 312f, 313f Costovertebral joint, 185f, 186f, 187f, 188–189f, 310, 312f, 313f, 570f Cowper’s glands. see Bulbourethral glands Cranial, 3t Cranial bones, 50f Cranial fossa, 14–18, 16f, 18t Cranial meninges, 210f Cranial nerves, 155–171, 156t abducens nerve, 119f, 150f, 152f, 156f, 156t, 160f, 161f, 162f, 165, 165f accessory nerve, 119f, 156f, 156t, 169f, 170, 170f cochlear nerve, 31f facial nerve, 31f, 119f, 156f, 156t, 165, 166f, 167f, 168f glossopharyngeal nerve, 88f, 119f, 156f, 156t, 168, 168f, 169f, 170f hypoglossal nerve, 119f, 156f, 156t, 169f, 170f, 171 oculomotor nerve, 111f, 119f, 150f, 152f, 156f, 156t, 160, 160f, 161f, 162f olfactory nerve, 156f, 156t, 157, 157f, 158f optic nerve, 88f, 111f, 112f, 119f, 141f, 150f, 156f, 156t, 158–160, 158f, 159f, 160f, 161f trigeminal nerve, 119f, 124f, 150f, 152f, 156f, 156t, 161f, 162f, 163–165, 163f, 164f, 167f trochlear nerve, 119f, 150f, 152f, 156f, 156t, 160f, 161f, 162f, 163 vagus nerve, 119f, 156f, 156t, 168–170, 168f, 169f, 170b, 170f vestibular nerve, 31f vestibulocochlear nerve, 119f, 156f, 156t, 166f, 167f, 168 Craniosynostosis, 46b Cranium, 13–47, 18f, 27f, 31f, 44f, 47f, 48f, 87f Cremaster muscle, 541f Cribriform plate, 16f, 21–22, 21f, 22f, 85f Cricoid cartilage, 251f, 253f, 257f, 258f, 261–264, 261f, 262f, 263f, 266f, 267f, 269f, 274f, 277f, 278f, 280f, 292f, 297f Cricothyroid ligament, 261f, 295f, 299f Crista galli, 16f, 17f, 21–22, 21f, 22f, 52f, 72f, 85f, 88f

Cruciform ligament, 194 Crura, 391–392, 395f, 396f Crus of diaphragm, 395f, 478f right, 555f Cubital tunnel, 613f, 614f Cuboid bone, 721–726, 729f, 731f, 747f Cuneiform bones, 721–726, 728f, 731f, 732f, 745f Cuneiform cartilage, 252f, 260f, 268f Curved planar reformation, 8, 11f Cystic artery, 428f Cystic disease, of lung, 315b Cystic duct, 428f, 433–436, 433f, 434f, 435f

D Danger space, 283f, 285f, 290f, 291f, 292f, 293t Dartos tunica muscle, 541f Deep, 3t Deep cervical artery, 242f Deep cervical fascia, deep layer of, 284f, 285f Deep cervical vein, 246f, 308f Deep circumflex iliac artery, 556f, 557f, 752f, 756f Deep circumflex iliac vein, 564f Deep dorsal vein of penis, 564f Deep fascia of dorsum of foot, 750f Deep fascia of sole of foot, 750f Deep femoral artery, 528f Deep inguinal nodes, 566f Deep inguinal ring, 532f Deep middle cerebral vein, 146f, 155f Deep palmar arch, 651–655, 653f, 658f Deep peroneal nerve, 760f Deep plantar branch, 756f Deep pockets, 314 Deep transverse metacarpal ligament, 643f Deep veins, 153, 153f Deltoid ligament, 692f, 734–735 Deltoid muscle, 301f, 396f, 571f, 572f, 574f, 575f, 576f, 577f, 578f, 579f, 580f, 581f, 582f, 583f, 584f, 585f, 586f, 587f, 588f, 589f, 591f, 592f, 593f, 594f, 595f, 590, 595t, 596f, 597f, 600f, 601f, 602f, 604f, 654f Deltoid tendon, 593f Deltoid tuberosity, 574f, 596f, 606f Dentate nucleus, 127, 127f, 128f Denticulate ligament, 210–212, 214f Dermatomes, 224f Descending aorta, 200f, 226f, 311f, 312f, 317f, 319f, 320f, 323f, 326f, 330f, 332f, 334f, 337f, 340f, 341f, 342f, 343f, 344f, 346f, 347f, 351–352, 355f, 356f, 357f, 358f, 360f, 361f, 364f, 365f, 366f, 370f, 371f, 372f, 374f, 376f, 377f, 378f, 380f, 383f, 384f, 385f, 388f, 390f, 393f, 395f, 396f Descending colon, 408f, 412f, 415f, 424f, 450f, 460f, 464–465, 465f, 466f, 467f, 486f, 496f Descending genicular artery, 756f, 757f Diaphragm, 208f, 231f, 269f, 324f, 332f, 345f, 362f, 378f, 391–392, 391t, 394f, 395f, 400f, 402f, 408f, 414f, 415f, 431f, 435f, 437f, 449f, 471f, 493f Diaphragmatic surfaces, 315, 315f, 316f Diencephalon, 110–114 Digastric muscle, 256f, 259f, 276f, 282f, 284f, 287f, 288f, 289f, 290f, 296f, 298, 298f, 299f, 300t Digital cube, 9f Digital veins, 656f, 759f Diploë, 16f, 17f, 22f Directional terminology, 3t Distal, 3t

Distal femur, 687, 688f Distal interphalangeal joint, 627f, 641f Distal radioulnar joint, 607f, 633, 634f, 640f Distal radius, 609 Distal tibiofibular joint, 690f Distal ulna, 610 DLDCF-alar fascia, 284f, 285f Dopamine, 123b Dorsal, 3t Dorsal carpal arch, 651–655 Dorsal cavity, 4, 5f, 6t Dorsal digital arteries, 756f Dorsal digital vein, 643f Dorsal fascia of foot, 750f Dorsal horn, 213f, 214, 223f Dorsal intercarpal ligament, 644f Dorsal interosseous muscle, 637f, 648f, 649f, 750f Dorsal pancreatic artery, 439f, 481f Dorsal pancreatic branch, 481f Dorsal radial carpal ligaments, 635–636 Dorsal ramus, 213f, 221f, 222f, 228f, 229 Dorsal root, 213f, 214, 216f, 218f, 221f, 222f, 226f, 227f, 228f Dorsal root ganglion, 177f, 178f, 213f, 214, 215f, 219f, 220f, 221f, 222f, 223f, 238f, 244f Dorsal rootlets, 223f Dorsal scapular artery, 650–651f Dorsal scapular nerve, 657f Dorsal vagal nucleus, 169f Dorsal venous arch, 759f Dorsal venous network, 656f Dorsalis pedis artery, 756f Dorsalis pedis vein, 759f Dorsum sellae, 17f, 19f, 21f, 23–25, 23f, 24f, 29f, 55f, 75f, 88f, 151f, 169f Duct, 397f Duct of Wirsung, 433–436, 439 Ductule, 397f Ductus deferens, 542f Duodenal bulb, 455f, 461f Duodenojejunal flexure, 461f Duodenum, 402f, 403f, 404f, 415f, 423f, 428f, 433f, 434f, 435f, 437f, 438f, 439f, 440f, 441f, 442f, 455f, 456f, 459f, 460, 461f, 463f, 469f, 481f, 483f, 485f, 486f, 490f second portion of, 434f third (horizontal) portion of, 453f, 462f, 469f, 483f Dura, 37f, 150f, 161f Dura mater, 87, 87f, 89f, 95f, 194f, 210–212, 210f, 213f, 221f, 223f Dural nerve root sleeve, 210–212, 213f, 221f, 222f Dural sinus, 87f, 146–153, 150f Dural spaces, 213f

E Ear external, 35–44, 35f inner, 31f, 34f, 35–44, 35f, 36f middle, 31f, 35–44, 35f, 36f Efferent duct, 542f Ejaculatory duct, 522f, 540f, 544, 544f Elbow, 606–626, 607f arterial supply of, 651 distal humerus of, 608 distal radius of, 609 fat pads of, 610, 612f, 623f joint capsule of, 610, 611f ligaments of, 612, 612f, 613f, 614f, 615f proximal radius of, 608, 608f venous drainage of, 655–656

INDEX Endocardium, 338, 338f, 348f Endolymph, 38–44 Endolymphatic duct, 37f, 38–44 Endolymphatic sac, 37f, 38–44 Endometrium, 529–530, 529f, 530f, 535f Epicardial fat, 335, 335f, 336f, 339f, 341f Epicardium, 335f, 338, 338f Epididymis, 522f, 540f, 542, 542f Epidural fat, 191f, 200f, 201f, 213f, 216f, 217f, 227f Epidural hematoma, 87b Epidural space, 87, 178f, 210–212, 210f, 213f Epiglottic valleculae, 265f Epiglottis, 251f, 252f, 253f, 256f, 257f, 259f, 261–264, 261f, 262f, 263f, 265f, 268f, 278f, 289f, 297f Epiploic appendages, 460f, 464–465, 464f Epiploic appendagitis, 465b Epiploic foramen, 400f, 404f Epithalamus, 114 Epitympanum, 35f, 37, 39f, 42f, 43f Erector spinae muscle, 201t, 204, 204f, 205f, 207f, 208f, 293f, 393f, 493f, 494f, 558f, 588f Esophageal hiatus, 269, 269f, 391–392, 394f, 432f Esophageal sphincter, 269, 269f Esophagus, 234f, 235f, 251f, 252f, 253f, 262f, 267f, 269, 269f, 270f, 279f, 285f, 292f, 293f, 297f, 314f, 318f, 319f, 320f, 321f, 324f, 326f, 327, 327f, 328f, 330f, 332f, 337f, 340f, 342f, 344f, 347f, 354f, 357f, 362f, 364f, 367f, 374f, 376f, 377f, 385f, 390f, 393f, 394f, 415f, 431f, 432f, 471f, 493f, 555f, 563f Estrogens, 535 Ethmoid air cells, 19f, 22f, 28f, 171f Ethmoid bone, 14f, 15f, 16f, 17f, 21–22, 21f, 22f, 26t, 49f, 51f, 67f, 74f, 76f, 157f Ethmoid bulla, 21–22, 21f, 22f, 68f, 72f, 73f Ethmoid notch, 16f, 18 Ethmoid sinuses, 21–22, 23f, 24f, 25f, 55f, 66, 66f, 67, 67f, 68f, 72f, 77f, 82f, 85f, 118f, 158f Eustachian tube, 30f, 32f, 33f, 35–37, 35f, 40f, 56f, 251, 251f, 252f, 284f Excretory ducts, 397 Extensor carpi radialis brevis muscle, 616t, 619f, 620f, 621f, 623f, 625, 625f Extensor carpi radialis brevis tendon, 618f, 620f, 639f Extensor carpi radialis longus muscle, 600f, 602f, 603f, 611f, 613f, 616t, 618f, 619f, 620f, 622f, 623f, 624f, 625, 625f, 654f Extensor carpi radialis longus tendon, 620f Extensor carpi ulnaris muscle, 616t, 618f, 619f, 626 Extensor carpi ulnaris tendon, 620f, 639f, 640f Extensor digiti minimi muscle, 616t, 618f, 619f, 625, 625f, 626 Extensor digiti minimi tendon, 620f, 621f, 637f Extensor digitorum longus muscle, 691f, 696f, 711–712 Extensor digitorum longus tendon, 692f, 747–748, 748f Extensor digitorum muscle, 611f, 616t, 618f, 619f, 621f, 623f, 625, 625f, 626, 643f Extensor digitorum tendon, 637f, 643f Extensor hallucis brevis muscle, 748 Extensor hallucis longus muscle, 712, 747–748 Extensor hallucis longus tendon, 692f, 746f Extensor indicis muscle, 605f, 625f, 626 Extensor pollicis brevis muscle, 605f, 616t, 618f, 619f, 625f, 626 Extensor pollicis brevis tendon, 620f, 621f

Extensor pollicis longus muscle, 605f, 616t, 618f, 625f, 626 Extensor pollicis longus tendon, 620f, 621f, 639f, 640f Extensor retinaculum, 636, 637f, 692f, 734 External anal sphincter, 464f, 516f, 527, 527f, 529f External auditory canal, 166f External auditory meatus, 4f, 14f, 30–32, 30f, 31f, 32f, 33f, 35, 35f, 36f, 40f, 41f, 42f, 43f, 49f, 57f, 60f External capsule, 101f, 106, 108f, 109f, 110f, 132f External carotid artery, 131f, 139f, 257f, 265f, 275f, 276f, 278f, 282f, 287f, 288f, 289f, 296f, 302, 302t, 303f, 304f, 305f, 306f, 307f, 325f External ear, 35–44, 35f, 166f External iliac artery, 470f, 488f, 539f, 555, 556f, 557f, 559f, 561f, 562f, 563f, 563t, 566f, 752f, 756f, 759f External iliac lymph nodes, 565 External iliac nodes, 491f, 566f External iliac vein, 470f, 488f, 539f, 557f, 559f, 563f, 564f, 759f External intercostal membrane, 391f External intercostal muscle, 391f, 493f, 495f External jugular vein, 256f, 257f, 260f, 263f, 266f, 270f, 275f, 279f, 288f, 289f, 290f, 291f, 292f, 293f, 302t, 308, 308f, 368 External landmarks, 4, 4f, 5f External oblique aponeurosis, 495f External oblique muscle, 208f, 492–494, 493f, 494f, 496f, 496t External occipital protuberance, 14f, 15f, 17f, 27–30, 27f, 29f, 202f External (cervical) os, 529–530, 530f External pudendal artery, 752f, 756f External sphincter muscle, 527f External table, 16f, 17f, 22f External venous plexuses, 246 Extrapelvic muscles, 507 Extreme capsule, 101f, 106, 108f, 132f Eye, 77f muscles of, 81

F Facial artery, 289f, 298f, 304f, 305f Facial bones, 13–57, 49f, 51f, 53f, 54f, 55f Facial nerve, 31f, 119f, 156f, 156t, 165, 166f, 167f, 168f Facial nerve canal, 30–32, 32f, 34f, 39f, 40f, 41f, 42f, 43f Facial nodes, 280f Facial vein, 257f, 289f, 308f Falciform ligament, 400f, 404, 406f, 407f, 408f, 408t, 409f, 410f, 414f, 415f, 416f, 418f, 422f, 423f, 443f, 444f, 447f Fallopian tube, 520f False pelvis, 506, 506f, 507f Falx cerebelli, 87, 89f Falx cerebri, 87, 87f, 88f, 89f, 95f, 147f Fascia, 635–641 Fat, in renal sinus, 451f Female reproductive organs, 529–539, 529f, 530f ovary, 520f, 523f, 525f, 529f, 530f, 531f, 532f, 533f, 535, 535f, 536f, 537f, 539f, 566f uterine tube, 529f, 530f, 532f, 533f, 535 uterus, 402f, 404f, 520f, 523f, 525f, 529– 530, 529f, 530f, 532f, 533f, 534f, 536f, 537f, 539f, 564f, 566f vagina, 513f, 515f, 516f, 519f, 520f, 521f, 528f, 529f, 530f, 531f, 535, 537f, 538f, 539f, 564f

767

Femoral artery, 240f, 512f, 514f, 515f, 526f, 528f, 539f, 555f, 556f, 557f, 558f, 559f, 560f, 661f, 666f, 680f, 682f, 752, 752f, 753f, 754f, 755f, 756f, 759f Femoral condyles, 711f Femoral head, 240f, 470f, 499f, 504f, 505f, 512f, 514f, 528f, 559f, 560f, 660, 660f, 661f, 663f, 664f, 666f, 668f, 669f, 670f, 671f, 674f Femoral neck, 499f, 505f, 662f, 663f, 664f, 667f, 669f, 670f, 671f, 689f Femoral nerve, 229, 237f, 240f, 510f, 526f, 666f, 759, 760f Femoral vein, 240f, 512f, 514f, 515f, 526f, 528f, 539f, 557f, 558f, 559f, 560f, 564f, 661f, 666f, 754f, 759f Femur, 241f, 504f, 505f, 506f, 512f, 526f, 538f, 661, 663f, 664f, 678f, 679f, 680f, 682f, 687, 689f, 691f, 692f, 694f, 697f, 758f Fibrous capsule, 62f, 63f, 451f Fibrous membrane of joint capsule, 694f Fibrous pericardium, 335, 335f Fibula, 659f, 687f, 689f, 690f, 693, 694f, 715f, 716f Fibular arteries, 757f Fibular collateral ligament, 694f Fibular head, 691f Fibular notch, 687–689 Fibular retinaculum, 748f Fibular (peroneal) vein, 759f Fifth lobe, 100–105 Fifth metatarsal, 746f Fifth rib, 598f Filum terminale, 199f, 210–212, 210f, 211f, 212f, 247f Fimbriae, 530f, 533f Fingers extensor mechanism of, 642f ligaments of, 641, 641b First distal phalanx, 746f First dorsal metatarsal artery, 756f First lumbar vein, 489f First lumbar vertebra, 331f First metatarsal, 746f First proximal phalanx, 747f Fissure for ligamentum teres, 415f for ligamentum venosum, 415f, 416f Flexor carpi radialis muscle, 615f, 616t, 617, 617f, 618f, 619f, 620f, 621f, 622f, 654f Flexor carpi radialis tendon, 621f, 639f, 640f Flexor carpi ulnaris muscle, 611f, 615f, 616t, 617, 617f, 618f, 619f, 621f, 625f Flexor carpi ulnaris tendon, 639f, 647f Flexor digiti minimi brevis muscle, 646, 647f, 749f, 750, 750f Flexor digitorum brevis muscle, 748, 749f Flexor digitorum longus muscle, 717 Flexor digitorum longus tendon, 692f, 748 Flexor digitorum profundus muscle, 611f, 615f, 616t, 618f, 619f, 620f, 621f, 623f, 624, 624f Flexor digitorum profundus tendon, 620f, 621f, 637f, 639f, 647f Flexor digitorum superficialis muscle, 611f, 613f, 617, 619f, 620f, 621f, 624f, 654f Flexor digitorum superficialis tendon, 621f, 639f, 647f Flexor hallucis brevis muscle, 746f, 747f, 749f, 750 Flexor hallucis longus muscle, 692f, 717, 748f Flexor hallucis longus tendon, 746f, 748, 749f Flexor pollicis brevis muscle, 647f, 648f Flexor pollicis longus muscle, 618f, 624, 624f Flexor pollicis longus tendon, 647f

768

INDEX

Flexor retinaculum, 636, 637f, 638f, 647f, 658f, 692f, 734 Flexor tendons, 658f Follicle, 525f Follicular cyst, 535, 535b Fontanels, 47 Foot, 719–750 arches of, 727 bony anatomy of, 719–726, 719f, 720–721f, 723f, 730f, 732f, 733f, 734f, 742f, 743f, 744f, 745f, 746f, 747f ligaments of, 735–736f muscles of, 748–750, 749f, 750f, 751t tendons of, 735f, 747–748 Foramen lacerum, 16f, 24f, 30–32, 33f, 169f Foramen magnum, 16f, 27–30, 27f, 28f, 29f, 45f, 53f, 54f, 58f, 59f, 169f, 171f Foramen of Luschka, 87–91, 90f, 91f Foramen of Magendie, 87–91, 90f Foramen of Monro, 87–91, 90f Foramen ovale, 16f, 23–25, 23f, 25f, 33f, 150f, 163f, 169f, 338 Foramen rotundum, 16f, 23–25, 23f, 25f, 26f, 30f, 51f, 58f, 70f, 75f, 76f, 150f, 163f Foramen spinosum, 16f, 23–25, 23f, 25f, 33f, 169f Forearm muscles, 616–626, 616t, 617f, 618f, 619f Fornix, 108f, 109f, 111f, 112f, 114, 115f, 117f, 118f, 124f, 128f, 153f, 155f, 530f Fossa ovalis, 338f Fourth lumbar vein, 489f Fourth metatarsal, 746f Fourth ventricle, 37f, 87–91, 90f, 91f, 93f, 94f, 95f, 96f, 98f, 99f, 102f, 111f, 112f, 120f, 123f, 124f, 125f, 126f, 127f, 128f, 129f, 162f, 163f, 165f, 167f, 169f superior aspect of, 98f Fovea capitis, 240f, 660f, 661, 662f, 665f, 667f Frontal bone, 14f, 15f, 16f, 17f, 18, 18f, 19f, 20f, 22f, 26t, 44f, 45f, 46f, 51f, 52f Frontal horn, of lateral ventricle, 87–91, 90f, 91f, 92f, 101f, 104f, 108f Frontal lobe, 93f, 97f, 100–105, 100f, 101f, 104f, 105f, 107f, 118f, 157f, 158f Frontal process, 50–53, 51f, 52f, 55f, 74f, 75f Frontal recess, 73f Frontal sinuses, 17f, 18, 19f, 20f, 51f, 52f, 56f, 66, 66f, 67f, 71, 71f, 75f, 79f, 99f, 157f, 251f Frontal suture, 44–46, 47f, 48f Frontopolar artery, 130, 133f Fundus, 520, 530f of gallbladder, 433–436, 433f, 434f of stomach, 456f, 457f, 463f of uterus, 529f, 530f

G Gallbladder, 403f, 404f, 414f, 415f, 417f, 418f, 419f, 423f, 425f, 433–436, 433f, 434f, 435f, 436f, 438f, 440f, 441f, 442f, 466f, 490f, 492f Gallbladder fundus, 428f Gastric impression, 414f Gastric vein, 427f, 432f Gastrocnemius bursa, 709 Gastrocnemius muscle, 673f, 688f, 690f, 691f, 697f, 716, 758f Gastrocolic ligament, 404, 408t Gastroduodenal artery, 428f, 430f, 436f, 438f, 439f, 440f, 441f, 472f, 477f, 479f, 480, 480f, 481f, 485f, 487f, 561f

Gastroesophageal junction, 419f, 455, 457f Gastrophrenic ligament, 404, 408t Gastrosplenic ligament, 400f, 404, 405f, 408t, 443, 443f Gemellus muscle, 240f, 661f Genicular arteries, 753 Geniculate ganglion, 43f Genioglossus muscle, 170f, 255f, 265f, 275f, 276f, 287f, 288f, 289f, 294, 294t, 295f, 296f, 297f, 298f Geniohyoid muscle, 170f, 265f, 295f, 297f, 298, 298f, 300t Genitofemoral nerve, 237f Genu, of corpus callosum, 99, 102f, 103f, 104f, 111f Gerdy’s tubercle, 677f, 687–689, 687f, 690f Gerota’s fascia. see also Renal fascia, 412f, 413f, 444–445, 448–451, 449f, 452f 453f Glabella, 14f, 15f Glandular layer, 398f Glandular tissue, 397, 397f, 398f Glenohumeral joint, 569f, 570–572, 571f, 572f, 573f, 578f, 579f Glenohumeral ligament, 574f, 575f, 576–577, 576f, 577f, 581f, 582f, 583f, 584f, 585f, 592f, 597f Glenoid fossa, 570–572, 571f, 572f, 573f, 575f, 576f, 584f, 585f, 595f, 597f, 598f Glenoid labrum, 574f, 575f, 576–577, 576f, 578f, 579f, 580f, 581f, 582f, 583f, 585f, 597f Glenoid ligament, 582f Glenoid process, 569f, 570–572, 571f, 572f, 579f, 580f, 582f, 583f, 585f, 591f, 592f, 593f Glisson’s capsule, 414 Globe, 75f, 77, 79f, 80f, 81f, 83f, 159f Globus pallidus, 101f, 106, 108f, 109f Glomerulus, 448, 451f Glossopharyngeal nerve, 119f, 156f, 156t, 168, 168f, 169f, 170f, 284f Glottis, 263f, 264, 266f, 268f Gluteal nerves, 237f Gluteal tuberosity, 661, 664f Gluteus maximus muscle, 239f, 240f, 470f, 499f, 500f, 508f, 509f, 511f, 512f, 514f, 515f, 528f, 539f, 541f, 558f, 560f, 661f, 666f, 667f, 668f, 673, 673f, 674f, 675f, 676t, 680f Gluteus medius muscle, 239f, 470f, 499f, 500f, 507, 508f, 509f, 511f, 512f, 514f, 539f, 541f, 661f, 662f, 666f, 667f, 673, 673f, 674f, 675f, 676t Gluteus minimus muscle, 470f, 507, 508f, 509f, 662f, 667f, 673, 673f, 674f, 675f, 676t Gnostic area, 105f Gonadal artery, 473f, 476, 484f, 556f Gonadal vein, 488f, 490, 556f Gonion, 4f, 49f, 57, 57f Gracilis muscle, 673f, 680f, 682f, 683 Gracilis tendon, 688f, 691f, 758f Gray matter, 101f, 213f, 214, 223f central, 120f organization of, 99–100 Gray scale, 8f Grays anatomy ligament, 611f Great anterior radicular artery, 241, 241b, 242f, 243f Great cardiac vein, 351f, 352f, 372f, 374f, 375, 379f, 382f Great cerebral vein, 146, 146f, 147f, 148f, 150f, 153f, 154f, 155f, 159f Great pancreatic artery, 439f, 481f Great pancreatic branch, 481f

Great saphenous vein, 528f, 692f, 757, 758f, 759f Great vessels, 351–368, 351f, 352f, 353f, 354f, 355f, 356f, 357f, 358f, 359f, 360f, 361f, 362f, 363f, 364f Greater curvature, of stomach, 455, 456f, 458f, 461f Greater omentum, 400–404, 402f, 404f, 405f, 406f Greater sac, 400f, 402f, 403f, 443f Greater sciatic notch, 498–500, 502f, 510f Greater trochanter, 240f, 499f, 502f, 504f, 505f, 509f, 510f, 559f, 661, 661f, 662f, 663f, 664f, 665f, 666f, 667f, 669f, 670f, 689f, 755f Greater tubercle, 569f, 572f, 573, 573f, 574f, 575f, 580f, 581f, 582f, 583f, 591f, 592f, 596f, 597f, 599f, 606f of humerus, 572f, 579f, 585f Greater wing of sphenoid bone, 14–18, 16f, 23f, 24f, 25f, 26f, 55f, 58f, 74f, 75f, 76f Gustatory area, 105f Guyon’s canal, 636, 638f Gyri, 99, 105f

H Hamate bone, 626b, 640f, 649f Hand, 626–646, 627f arterial supply of, 651–655 bony anatomy of, 626, 627f, 628f, 629f, 630f, 631f joints of, 635 venous drainage of, 656, 656f Hard palate, 19f, 50–53, 50f, 53f, 64f, 70f, 157f, 251f, 253f, 254f, 262f, 272f, 287f, 297f Hartmann’s pouch, 434f Hashimoto’s thyroiditis, 277b Haustra, 460f, 464–465, 464f, 466f Head external landmarks of, 4f of fibula, 748f of pancreas, 419f, 423f, 426f, 436f, 437f, 438f, 439f, 440f, 441f, 442f, 459f, 469f, 481f Heart, 314f, 333–348, 432f, 449f apex of, 325f, 333, 333f, 334f, 339f, 351f, 370f, 379f base of, 333, 333f, 334f, 339f chambers of, 338–339, 338f, 339f, 340f, 341f, 342f, 343f, 344f, 345f, 346f, 347f, 348f, 349f, 350f circulation of blood through, 364 conduction system of, 338f, 339 diaphragmatic surface of, 333f, 334f inferior border of, 333, 334f mediastinal compartments, 324f pericardium in, 335, 335f, 336f, 337f, 337t pulmonary surface of, 333, 333f, 334f sternocostal surface of, 333, 334f superficial landmarks of, 333, 333f, 334f superior border of, 333, 334f valves of, 348, 348f, 349f, 350f walls of, 338, 338f Hemiazygos veins, 332f, 342f, 388, 388f, 390f, 489f Hepatic artery, 400f, 414f, 418f, 433f, 443f, 447f, 488f, 492f, 563f proper, 561f Hepatic flexure, 415f, 461f, 463f, 467f, 468f, 469f Hepatic veins, 419f, 433f, 488f, 489f, 491, 563f Hepatoduodenal ligament, 404, 404f, 408t

INDEX Hepatoesophageal ligament, 408t Hepatogastric ligament, 404, 404f, 408t Hepatorenal ligament, 408t Herpes zoster virus, 212b Heschl’s gyrus, 100–105, 105f Hilum, 315f, 318f, 319f, 448–451, 448f of spleen, 405f, 443f, 444f Hip, 660–687 bones, 498–500 bony anatomy of, 660–661, 660f, 661f, 662f, 664f bursae of, 672, 672f joint capsule of, 672 labrum of, 665, 665f, 667f, 668f ligaments of, 665–671, 666f, 667f, 668f muscles of, 672–687, 673f, 674f, 675f, 677f, 678f, 683f, 684f, 685f, 686t synovial capsule of, 672 Hippocampus, 108f, 114, 115f, 116f, 117f, 118f, 123f, 124f damage to, 116b Hook of hamate, 627f, 628f, 629f, 630f, 634f, 649f Horizontal fissure, 318f, 362f Horizontal long axis (HLA) view, 380–382, 380f, 382f Humeral head, 570–572, 570f, 572f, 573, 573f, 574f, 577f, 579f, 580f, 582f, 585f, 588f, 589f, 597f, 599f, 605f, 606f Humerus, 232f, 569f, 573, 573f, 574f, 585f, 587f, 593f, 594f, 595f, 596f, 599f, 600f, 601f, 602f, 603f, 604f, 605f, 606f, 607f, 609f, 610f, 611f, 652f, 654f, 657f Hyoepiglottic ligament, 261–264, 261f Hyoglossus muscle, 255f, 265f, 275f, 276f, 288f, 289f, 294, 294t, 295f, 296f, 298f, 299f Hyoid bone, 170f, 251f, 253f, 256f, 257f, 258f, 259f, 261f, 262f, 268f, 274f, 277f, 280f, 290f, 295f, 297f, 298, 299f, 304f, 308f Hypoglossal canal, 17f, 27–30, 27f, 28f, 34f, 41f, 59f, 169f, 170f, 171f Hypoglossal nerve, 119f, 156f, 156t, 169f, 170f, 171 Hypoglossus muscle, 287f Hypophysis, 112 Hypothalamic nuclei, 111f Hypothalamus, 111f, 112, 112f, 115f, 119f, 157f Hypothyroidism, 277b Hypotympanum, 35f, 38, 41f, 42f, 43f

I Ileal artery, 485f Ileal branch, 485f of ileocolic artery, 485f Ileocecal valve, 460, 460f, 461f, 463f, 464f Ileocolic artery, 482–484, 485f Ileum, 415f, 424f, 437f, 460f, 461f, 464f, 465f, 466f, 467f, 484f, 485f Iliac crest, 204f, 206f, 207f, 493f, 495f, 498f, 502f, 503f, 504f, 506f, 510f, 511f, 664f, 673f Iliac fossa, 498, 499f, 503f, 504f, 506f, 664f Iliac muscle, 493f Iliac vein, 563–565 Iliacus muscle, 208f, 237f, 496f, 499f, 504f, 510f, 511f, 513t, 537f, 541f, 557f, 667f, 674f, 675f, 677 Iliococcygeus muscle, 513, 513f Iliocostalis cervicis muscle, 201t, 204f Iliocostalis lumborum muscle, 201t, 204f, 208f

Iliocostalis muscle, 201t, 204, 204f, 205f, 209f, 494f Iliocostalis thoracis muscle, 201t, 206f Iliofemoral ligament, 661, 661f, 665f, 666f, 667f, 669f, 671f Iliohypogastric nerve, 237f Ilioinguinal nerve, 237f Iliolumbar artery, 556f, 562f, 752f Iliolumbar veins, 489f, 564f Iliopsoas bursa, 672 Iliopsoas muscle, 470f, 493f, 508f, 509f, 510f, 512f, 514f, 539f, 559f, 661f, 662f, 666f, 668f, 674f, 675f, 677, 677f, 755f Iliotibial band, 661f, 662f, 666f, 673f, 675f, 677f, 679–682, 682f, 688f, 694f, 702f Ilium, 192f, 193f, 239f, 462f, 463f, 498, 498f, 499f, 500f, 501f, 503f, 508f, 509f, 511f, 512f, 523f, 527f, 539f, 557f, 558f, 560f, 660, 662f, 665f, 668f, 670f, 671f, 674f, 689f IMA. see Inferior mesenteric artery Image display, 7, 7f, 8f, 9f IMV. see Inferior mesenteric vein Incisura, 87 Incus, 31f, 35–37, 35f, 39f, 40f, 42f, 43f Indirect inguinal hernias, 507b Inferior, 3t Inferior acetabular labrum, 667f Inferior anastomotic vein, 146f Inferior angle, 569f Inferior aortic recess, 337t Inferior articular process, 175f, 176f, 177f, 180f, 182f, 188–189f, 189f, 200f Inferior cerebellar peduncle, 119f, 125f, 126f, 130f Inferior colliculi, 112f, 117f, 119f, 120–123, 120f, 121f, 126f Inferior compartment, of mediastinum, 324, 324t Inferior constrictor muscle, 260f, 263f, 266f, 287f, 290f, 291f, 292f, 294, 294t, 295f, 297f Inferior costal facet, 175f Inferior end plate, 188–189f Inferior epigastric artery, 532f, 555, 556f, 557f, 559f, 752f, 756f Inferior epigastric vein, 559f, 564f Inferior frontal gyrus, 105f Inferior gemellus muscle, 666f, 668f, 673f, 674f, 676, 676t Inferior glenoid labrum, 575f, 579f, 584f, 585f Inferior gluteal artery, 555f, 556f, 558f, 560f, 562f, 752f, 756f Inferior gluteal nerve, 237f Inferior gluteal vein, 558f, 564f Inferior ischial ramus, 502f, 503f Inferior labrum, 582f Inferior lingular segmental bronchus, 322f Inferior lobe, 316f, 318f, 322f Inferior lobe bronchus, 322f Inferior margin, 414f Inferior mediastinum, 324f Inferior medullary velum, 87–91, 93f, 95f Inferior mesenteric artery (IMA), 462f, 464f, 468f, 471f, 472f, 473f, 475f, 480f, 484f, 485f, 486, 486f, 487f, 488f, 555f, 556f, 561f, 562f Inferior mesenteric nodes, 491f Inferior mesenteric vein (IMV), 424f, 468f, 484f, 564f Inferior nasal conchae, 15f, 19f, 22f, 49f, 51f, 52f, 54f, 56, 56f, 67f, 68f, 69f, 70f, 72f, 84f, 258f Inferior nasal meatus, 22f, 52f, 56f, 67f, 68f, 84, 84f

769

Inferior nuchal line, 202f Inferior oblique capitis muscle, 207f, 284f Inferior oblique muscle, 81, 81f, 83f, 160f Inferior orbital fissure, 30f, 49f, 67f, 73, 74f, 76f Inferior pancreaticoduodenal artery, 482–484, 485f Inferior petrosal sinus, 146f Inferior pharyngeal constrictor muscle, 285f Inferior phrenic artery, 471f, 473, 473f, 488f, 555f, 563f Inferior phrenic vein, 488, 489f Inferior pubic ramus, 498f, 499f, 502f, 503f, 505f, 663f, 664f Inferior pudendal vein, 564f Inferior pulmonary vein left, 312f right, 312f Inferior rectus muscle, 81, 81f, 82f, 83f, 159f, 160f Inferior sagittal sinus, 88f, 146, 146f, 155f Inferior suprarenal artery, 444f, 473f Inferior thoracic aperture, 310 Inferior thyroid artery, 279f, 303f, 304f Inferior thyroid vein, 303f, 352f, 379f Inferior vena cava (IVC), 245f, 311f, 318f, 324f, 337f, 344f, 346f, 347f, 348f, 351f, 352f, 356f, 357–360, 359f, 362f, 364f, 370f, 378f, 379f, 387f, 388f, 390f, 394f, 395f, 396f, 400f, 401f, 403f, 405f, 406f, 407f, 412f, 413f, 414f, 415f, 416f, 417f, 418f, 419f, 420f, 421f, 422f, 423f, 424f, 425f, 426f, 427f, 428f, 429f, 430f, 431f, 432f, 433f, 436f, 437f, 438f, 439f, 440f, 441f, 442f, 443f, 444f, 446f, 447f, 448f, 453f, 454f, 457f, 458f, 459f, 462f, 468f, 474f, 475f, 476f, 477f, 478f, 479f, 481f, 482f, 483f, 484f, 488f, 489f, 490f, 492f, 493f, 496f, 556f, 557f, 563–565, 563f, 564f, 759f Inferior vertebral notch, 175f, 188–189f, 189f Infracolic compartment, 408, 408f, 411t Infracolic spaces, 411t Infraglenoid tubercle, 570–572, 571f, 572f, 573f, 605f Infrahyoid muscle, 274f, 298, 300t, 396f Infraorbital canal, 51f, 75f Infraorbital foramen, 49f, 50–53, 52f, 73, 74f, 75f Infraorbital groove, 72f, 74f Infrapatellar bursa, 709 Infrapatellar fold, 694f Infraspinatus bursa, 597f Infraspinatus muscle, 301f, 572f, 574f, 575f, 578f, 580f, 581f, 582f, 583f, 587f, 589f, 591f, 592f, 593f, 595f, 590, 595t, 596f, 597f, 604f, 654f Infraspinatus tendon, 577f, 580f, 584f, 585f, 595f Infraspinous fossa, 570–572, 571f, 596f Infundibular nucleus, 111f Infundibulum, 21–22, 22f, 72–73, 72f, 73f, 88f, 111f, 112, 112f, 113f, 119f, 157f, 530f, 533f Inguinal canal, 495f, 507, 541f Inguinal ligament, 208f, 237f, 492–494, 493f, 495f, 508f, 510f, 541f, 557f, 752f, 759f Inguinal lymph node, 541f, 565 Inner ear, 31f, 34f, 35–44, 35f, 36f, 133f, 166f Innominate bones, 498–500 Innominate trunk, 365 Insula, 100–105, 101f, 103f, 104f, 105f, 106f, 107f, 108f, 109f, 113f, 124f, 132f Interatrial septum, 312f, 336f, 338, 338f, 342f, 343f, 347f

770

INDEX

Intercarpal joints, 633 Intercarpal ligaments, 635–636 Intercondylar eminence, 687–689, 687f, 689f, 690f Intercondylar fossa, 664f, 687, 688f, 689f, 693f Intercostal artery, 241b, 242f, 244f, 245f Intercostal muscles, 391–392, 391f, 391t, 392f, 395f, 396f, 397f, 589f, 602f Intercostal nerves, 228f Intercostal spaces, 310 Intercostales intimi muscle, 391f Interior sagittal sinus, 147f Interlobar arteries, 474f, 475f Interlobar fissure, 415f Interlobar veins, 474f, 490 Interlobular arteries, 474f Interlobular veins, 474f Intermediate antebrachial vein, 656f Intermetatarsal joint, 727 Internal auditory (labyrinthine) artery, 139f, 145f Internal auditory canal, 16f, 17f, 30–32, 31f, 33f, 35f, 36f, 39f, 40f, 42f, 98f, 165f, 167f, 168f, 169f Internal capsule, 101f, 106, 108f, 109f, 110f, 132f Internal carotid artery, 70f, 113f, 114f, 124f, 130–138, 131f, 131t, 132f, 133f, 134f, 134t, 135f, 136f, 137f, 139f, 142f, 143f, 144f, 150f, 151f, 152f, 161f, 162f, 257f, 260f, 265f, 272f, 275f, 276f, 278f, 282f, 284f, 286f, 287f, 288f, 289f, 296f, 302, 302t, 303f, 304f, 305f, 306f, 307f, 325f Internal cerebral vein, 146f, 148f, 153, 153f, 154f, 155f Internal iliac artery, 556f, 557f, 558f, 561f, 562f, 563t, 566f, 752f, 756f, 759f anterior trunk of, 559f, 561f posterior trunk of, 559f Internal iliac (hypogastric) nodes, 491f, 566f Internal iliac vein, 488f, 557f, 558f, 559f, 563–565, 563f, 564f, 759f Internal intercostal membrane, 391f Internal intercostal muscle, 391f, 495f Internal jugular lymph node, 273f, 275f, 278f, 282t, 286f, 287f, 288f, 289f Internal jugular (deep cervical) nodal chain, 280f Internal jugular vein, 35f, 146, 146f, 153f, 166f, 234f, 235f, 236f, 257f, 258f, 259f, 260f, 263f, 265f, 266f, 267f, 270f, 272f, 273f, 275f, 276f, 277f, 278f, 279f, 280f, 282f, 284f, 285f, 286f, 287f, 288f, 289f, 290f, 292f, 293f, 296f, 302t, 303f, 308, 308f, 368, 656f Internal landmarks, 4, 5t Internal mammary, 331f arteries, 365 Internal oblique aponeurosis, 495f Internal oblique muscle, 208f, 492–494, 493f, 494f, 495f, 496f, 496t Internal obturator muscle, 559f Internal occipital protuberance, 16f, 27–30, 29f, 30f, 33f, 45f, 147f, 148f Internal os, 530f Internal pudendal artery, 555f, 556f, 560f, 562f, 752f Internal pudendal vein, 564f Internal sphincter muscle, 527f Internal table, 16f, 17f, 22f Internal thoracic artery, 304f, 365b, 374f, 654f Internal venous plexuses, 246 Interosseous artery, 651 Interosseous membrane, 607f, 610, 690f, 691f Interosseous muscles, 605f, 644f, 646f, 749f Interosseous talocalcaneal ligament, 734–735

Interpeduncular cistern, 96–97, 97f, 98f, 144f Interphalangeal joints, 627f, 641f, 727 Interspinous ligament, 194, 195f, 198f, 199f Interstitial septa, 323f Intertarsal joints, 727 Intertransverse ligament, 198f, 207f Intertrochanteric crest, 661, 665f Intertrochanteric line, 661, 664f, 665f Interventricular foramen, 87–91, 90f, 92f, 95f Interventricular grooves, 338 Interventricular septum, 334f, 336f, 338, 338f, 342f, 343f, 344f, 345f, 348f, 364f, 376f, 377f, 378f, 380f, 381f, 382f, 384f Intervertebral disk, 177f, 178f, 180f, 194f, 198f, 219f, 221f, 247f Intervertebral disk space, 188–189f Intervertebral foramen, 175f, 176f, 183f, 188–189f, 198f, 215f, 219f, 231f, 244f Intervertebral veins, 246, 246f, 248f Intestinal lymph vessels, 331f Intestinal trunk, of cisterna chyli, 491f Intestines, 460–465, 460f, 461f, 462f, 463f, 464f, 465f, 466f, 467f, 468f, 469f, 470f Intrahepatic bile ducts, 433–436 Intrahepatic ducts, 434f Intrathecal sac, 217f, 249f Ipsilateral, 3t Iris, 77 Ischial ramus, 504f Ischial spine, 502f, 503f, 505f, 506f, 510f Ischial tuberosity, 499f, 502f, 505f, 506f, 507f, 513f, 518f, 519f, 526f, 528f, 664f, 665f, 668f Ischioanal fossa, 514f, 515f, 518f, 519f Ischiofemoral ligament, 665f, 666f, 667f, 671f Ischium, 239f, 498–500, 498f, 499f, 502f, 503f, 504f, 505f, 512f, 513f, 515f, 517f, 519f, 526f, 527f, 539f, 660, 660f, 662f, 663f, 665f, 666f, 670f, 671f, 675f, 755f Island of Reil, 100–105 Isthmus, of thyroid gland, 277, 277f, 279f IVC. see Inferior vena cava

J Jejunal arteries, 485f Jejunal branches, 485f Jejunum, 437f, 460, 460f, 461f, 462f, 463f, 465f, 466f, 467f, 468f, 469f, 485f Joint capsule, 62f, 576f, 581f, 582f, 584f, 597f, 610f, 611f, 669f, 699f Jugular foramen, 16f, 30–32, 31f, 33f, 41f, 169f Jugular fossa, 25f, 27f, 30–32, 30f, 34f, 169f, 280f Jugular lymph node, 279f Jugular notch, 4f, 310, 310f Jugular veins, 308 Juxtavisceral (visceral) nodes, 280f

K Kidney, 403f, 409f, 419f, 435f, 444f, 448, 473f Knee, 687–717, 758f articulations of, 694 bony anatomy of, 687–693, 689f, 690f, 707f, 709f, 758f bursae of, 709, 710f joint capsule of, 694, 694f ligaments of, 695f, 696f, 699, 699f, 700f, 708f menisci of, 695, 698f, 701f tendons of, 709

Kohlrausch’s fold, 527, 527f Kyphosis, 173b Kyphotic curve, 173f

L L1, L2, L3, L4, L5,

187f, 188–189f, 190f, 215f, 243f, 483f 187f, 188–189f, 215f 187f, 188–189f, 215f 187f, 188–189f, 215f, 450f 187f, 188–189f, 190f, 215f, 245f, 454f, 483f, 752f L5-S1 disk space, 188–189f Labia majora, 520f, 529f Labia minora, 520f, 529f Labyrinths, 22f, 67 Lacrimal apparatus, 84, 84f Lacrimal bones, 26t, 49f, 50, 51f, 55f, 67f, 74f, 75f, 76f Lacrimal canaliculi, 84, 84f Lacrimal fossa, 73, 74f Lacrimal gland, 79f, 80f, 83f, 84, 84f Lacrimal groove, 49f, 50, 51f, 73, 74f, 75f Lacrimal sac, 77f, 78f, 84, 84f Lactiferous ducts, 397, 397f Lactiferous sinus, 397f Lacunar stroke, 134b Lambda, 14f, 47, 48f Lambdoidal suture, 14f, 15f, 17f, 18f, 44–46, 44f, 45f, 46f, 48f Lamina, 174f, 178f, 182f, 183f, 185f, 188–189f, 190f, 198f, 200f, 203f, 213f, 214f, 220f Lamina papyracea, 21–22, 67f Lamina terminalis, 87–91, 90f, 95f, 102f, 111f Landmarks, 2–4, 4f, 5f, 5t Large intestine, 464–465 Laryngeal nerve, 168f Laryngeal prominence, 261–264, 261f Laryngeal ventricle, 261f, 262f, 264, 297f Laryngopharynx, 251f, 252f, 253f, 256, 257f, 258f, 259f, 260f, 262f, 278f Larynx, 251f, 257f, 260f, 261–264, 261f, 262f, 263f, 264b, 266f, 267f, 268f, 278f Lateral, 3t Lateral angle, 569f Lateral anterior malleolar artery, 756f Lateral aperture, 87–91, 90f, 91f Lateral basal segmental bronchus, 322f Lateral cervical ligament, 533f, 539f Lateral circumflex femoral artery, 752f, 756f Lateral collateral ligament, 62f, 694f, 700 Lateral condyle, 606f, 610f, 690f of humerus, 602f Lateral cutaneous nerve, 657f, 760f Lateral epicondyle, 574f, 599f, 603f, 605f, 606f, 608, 610f, 611f, 664f, 687, 687f, 689f of humerus, 605f Lateral epitympanic recess, 37 Lateral femoral condyle, 687, 688f, 689f, 690f, 694f, 696f Lateral femoral cutaneous nerve, 237f Lateral (Sylvian) fissure, 94f, 97f, 98f, 99, 100f, 101f, 105f, 106f, 107f, 113f, 116f, 117f, 122f, 123f, 132f, 149f Lateral geniculate nucleus, 119f Lateral inferior genicular artery, 756f Lateral intercondylar tubercle, 687–689, 687f Lateral lenticulostriate arteries, 130–134 Lateral ligament, 61, 63f Lateral longitudinal arch, 727 Lateral malleolus, 690f, 692f, 693, 748f Lateral margin, 569f

INDEX Lateral mass, 179f, 180f, 181f, 182f, 192f, 193f, 196f, 197f, 225f, 498f of sacrum, 499f, 500f, 501f, 524f Lateral meniscus, 690f, 695, 696f, 703f Lateral palpebral ligament, 84f Lateral patellar retinaculum, 688f Lateral pectoral nerve, 232f, 657f Lateral pterygoid muscle, 60f, 63, 63f, 65f, 284f, 286f Lateral pterygoid plate, 23f, 25f, 26f Lateral rectus muscle, 77f, 78f, 79f, 81, 82f, 83f, 160f Lateral sacral artery, 242f, 556f, 752f Lateral sacral veins, 564f Lateral segmental bronchus, 322f Lateral semicircular canal, 39f, 41f, 42f Lateral semicircular duct, 37f Lateral superior genicular artery, 756f Lateral supracondylar ridge, 574f, 606f Lateral tarsal artery, 756f Lateral tibial plateau, 689f, 690f Lateral tuberal nuclei, 111f Lateral ventricle, 87–91, 88f, 93f, 96f, 101f, 103f, 106f, 111f, 113f, 118f, 125f, 148f, 154f, 218f body of, 90f, 91f Latissimus dorsi muscle, 208f, 395f, 396f, 495f, 587f, 589f, 590t, 602f, 604f Le Fort fractures, 53b Left adrenal gland, 444–445, 444f, 445f, 446f, 447f, 458f Left anterior descending artery, 339f, 345f, 351f, 361f, 370–371, 370f, 371b, 371f, 372f, 373f, 374f, 375f, 376f, 378f, 381f, 382f, 384f Left aortic sinus, 350f, 353f, 373f Left ascending pulmonary artery, 356f, 358f Left atrial appendage, 339f, 351f, 361f Left atrioventricular valve, 338f, 348, 348f Left atrium, 311f, 312f, 334f, 336f, 338–339, 338f, 340f, 341f, 342f, 343f, 346f, 347f, 348f, 352f, 355f, 356f, 358f, 359f, 361f, 362f, 364f, 370f, 371f, 372f, 374f, 375, 375f, 376f, 379f, 380f, 381f, 382f, 383f, 385f, 386f, 387f Left auricle, 338–339, 370f, 379f, 380f Left brachiocephalic vein, 303f, 318f, 325f, 327f, 331f, 347f, 351f, 352f, 363f, 365f, 367f, 368f, 369f, 370f, 379f, 394f Left bundle branch, 338f Left circumflex artery, 372f, 373f, 374f, 375f Left clavicle, 368f, 569f Left colic artery, 486, 486f, 487f, 556f Left colic flexure, 460f, 464f Left common carotid artery, 231f, 234f, 302, 304f, 305f, 324f, 325f, 327f, 348f, 351f, 352f, 358f, 365, 365f, 366f, 367f, 368f, 370f Left common iliac artery, 454f, 472f, 479f, 486f, 494f, 555, 556f, 561f, 562f Left coronary artery, 334f, 350f, 353f, 370–371, 370f, 373f, 387f Left crus, 394f, 395f, 396f of diaphragm, 445f, 447f, 493f Left descending pulmonary artery, 356f, 358f, 359f Left external carotid artery, 304f, 305f Left external iliac artery, 472f, 561f Left femoral artery, 755f Left femoral nerve, 523f Left gastric artery, 428f, 430f, 471f, 472f, 477, 477f, 478f, 479f, 480f, 481f, 482f, 485f, 487f, 488f, 555f, 563f Left gastric vein, 564f Left gastroepiploic artery, 428f, 477f, 480–481, 481f

Left gonadal artery, 471f, 476f, 479f, 486f, 555f Left gonadal vein, 476f, 490 Left hepatic artery, 428, 428f, 430f, 472f, 477f, 480f, 481f Left hepatic duct, 433f, 434f, 437f Left hepatic vein, 418f, 420f, 421f, 424f, 429, 430f, 431f Left inferior lobe, 315f, 316f, 317f, 320f, 341f, 363f bronchus, 321f, 322f, 361f Left inferior phrenic vein, 488, 488f Left inferior pulmonary vein, 312f, 341f, 342f, 351f, 352f, 353–357, 356f, 358f, 359f, 361f, 363f, 372f, 374f Left infracolic space, 408, 408f, 411f Left intermediate bronchus, 337f Left internal carotid artery, 304f, 305f Left internal iliac artery, 471f, 472f, 555f, 561f Left internal jugular vein, 234f, 278f, 331f, 365f, 369f Left internal thoracic arteries, 365 Left internal thoracic vein, 379f Left jugular trunks, 331f Left kidney, 243f, 400f, 401f, 410f, 412f, 413f, 423f, 441f, 442f, 443f, 444f, 445f, 446f, 447f, 448f, 450f, 452f, 453f, 454f, 524f Left lobe, of liver, 406f, 407f, 414f, 415, 415f, 416f, 418f, 427f, 432f, 447f, 457f, 465f anterior segment of, 423f inferior lateral segment of, 430f lateral segment of, 420f, 422f, 423f medial segment of, 420f, 422f, 423f, 430f posterior segment of, 420f, 423f superior lateral segment of, 430f Left lower quadrant, 6, 6f, 7t Left lumbar trunks, 331f Left lung, 243f, 314f, 319f, 354f, 385f, 420f, 449f Left main coronary artery, 339f, 361f, 371f, 373f, 374f, 375f Left main portal vein, 424, 424f Left main pulmonary artery, 328f Left mainstem bronchus, 311f, 315f, 317f, 318f, 319f, 320, 320f, 321f, 322f, 334f, 346f, 347f, 355f, 356f, 357f, 358f, 360f, 363f, 386f Left marginal artery, 351f, 370f Left marginal vein, 379f Left oblique fissure, 315f, 316f, 317f, 320f Left ovarian vein, 564f Left paracolic gutter, 408, 408f, 411f Left pectoralis major muscle, 367f Left pectoralis minor muscle, 367f Left perirenal space, 413f Left phrenic nerve, 231f Left phrenic vein, 563f Left popliteal artery, 755f Left portal vein, 418f, 419f, 421f, 564f Left posterior interventricular vein, 352f Left posterior ventricular vein, 375, 379f Left psoas muscle, 496f Left pubic arch, 518f Left pulmonary artery, 231f, 317f, 318f, 320f, 326f, 351f, 352, 352f, 355f, 356f, 357f, 358f, 359f, 360f, 363f, 365f, 368f, 370f, 379f, 386f Left pulmonary veins, 318f, 334f, 337f, 346f, 363f, 370f, 381f, 386f Left pulmonary venous recess, 337f Left pulmonic recesses, 337f, 337t Left renal artery, 472f, 474f, 475f, 479f, 486f, 488f, 561f, 563f

771

Left renal pelvis, 454f, 524f Left renal vein, 388f, 440f, 442f, 448f, 472f, 474f, 475f, 483f, 490, 490f Left seminal vesicle, 523f Left subclavian artery, 231f, 233f, 318f, 324f, 327f, 348f, 351f, 352f, 358f, 363f, 365, 365f, 366f, 367f, 368f, 370f, 650–651f Left subclavian trunk, 331f Left subclavian vein, 331f, 368f, 369f Left subhepatic space, 408f, 410f Left subphrenic space, 408f, 409f, 410f Left superior intercostal vein, 388f Left superior lobe, 315f, 316f, 317f, 320f, 341f, 363f Left superior lobe bronchus, 317f, 321f, 322f, 363f Left superior pulmonary vein, 337f, 351f, 352f, 353–357, 356f, 357f, 358f, 359f, 360f, 363f, 368f, 380f Left suprarenal vein, 491 Left testicular vein, 564f Left triangular ligament, 414f Left upper quadrant, 6f Left ureter, 453f, 454f, 523f, 524f Left vagus nerve, 231f Left vas deferens, 523f Left ventricle, 231f, 311f, 312f, 334f, 336f, 338–339, 338f, 339f, 340f, 341f, 342f, 343f, 344f, 345f, 346f, 348f, 349f, 350f, 351f, 352f, 353f, 359f, 363f, 364f, 366f, 369f, 370f, 372f, 373f, 375f, 376f, 377f, 378f, 379f, 380f, 381f, 382f, 384f, 386f, 387f, 394f, 420f, 427f, 432f Left ventricular myocardium, 372f, 380f Left ventricular outflow tract (LVOT), 380–382, 387f, 388f Left ventricular wall, 349f Left vertebral artery, 286f, 366f, 379f Lens, 77, 77f, 78f, 81f, 159f Lenticulostriate arteries, 132f Lentiform nucleus, 101f, 106, 107f, 108f, 109f, 110f, 113f, 132f Lesser curvature, of stomach, 455, 456f, 458f, 461f Lesser omentum, 400–404, 400f, 404f, 409f, 443f, 457f attachment of, 414f Lesser sac, 400f, 402f, 403f, 406f, 409f, 410f, 443f Lesser sciatic notch, 502f Lesser trochanter, 241f, 493f, 499f, 505f, 661, 662f, 663f, 664f, 665f, 667f, 670f, 671f of femur, 504f Lesser tubercle, 569f, 572f, 573, 574f, 575f, 581f, 592f, 596f, 599f, 606f Lesser wing of sphenoid bone, 14–18, 16f, 23f, 24f, 25f, 74f Levator ani muscle, 208f, 239f, 513, 513t, 514f, 515f, 516f, 517f, 526f, 527f, 528f, 537f, 539f Levator scapulae muscle, 256f, 260f, 263f, 267f, 270f, 275f, 285f, 288f, 289f, 290f, 291f, 292f, 293f, 299f, 300–301, 300t, 301f, 587, 587f, 588f, 590t Levator scapular muscle, 203f Levator veli palatini muscle, 284f, 295f Levatores costarum muscles, 207f, 391–392, 391t, 392f Lienorenal ligament, 400f, 443, 443f Ligament of Humphry, 695 Ligament of Treitz, 460, 461f Ligament of Wrisberg, 695 Ligamentum arteriosum, 231f, 351f, 352, 356f, 370f Ligamentum flava, 196, 198f, 199f, 200f, 201f, 226f

772

INDEX

Ligamentum nuchae, 194, 194f, 195f, 199f, 203f, 204f, 285f Ligamentum teres, 408t, 414f, 661, 661f, 662f, 665f, 666f, 667f, 669f, 670f, 672 fissure for, 415f Ligamentum venosum, 415, 421f, 422f fissure for, 406f, 407f, 415f, 416f Limbic system, 115–116, 115f Linea alba, 492–494, 494f, 495f, 499f Linea aspera, 661, 664f, 682f Lingual artery, 297f, 298f, 304f, 305f Lingual frenulum, 271f Lingual nerve, 298f Lingual tonsils, 251–256, 251f, 252f, 253f, 255f, 296f Lingual vein, 276f, 298f Lingula, 315f, 318f, 322f, 363f Lister’s tubercle, 607f, 627f Liver, 243f, 332f, 336f, 345f, 346f, 347f, 378f, 385f, 386f, 390f, 395f anatomy of, 2f, 400f, 401f, 402f, 403f, 405f, 406f, 408f, 409f, 410f, 412f, 413f, 414–429, 424f, 425f, 433f, 435f, 440f, 441f, 442f, 443f, 445f, 446f, 448f, 449f, 450f, 452f, 462f, 468f anterior view of, 414f with fissures, 415f portal hepatic system of, 424, 424f, 425f, 426f, 427f posterior view of, 414f segmental anatomy of, 418, 418f, 419f, 420f, 421f, 422f, 423f surface anatomy of, 415–417, 415f, 416f, 417f vasculature of, 428–429, 428f, 429f, 430f, 431f, 432f Lobar bronchi, 320 Lobule, of testis, 542f Long thoracic nerve, 232f, 657f Longissimus capitis muscle, 201t, 203f, 204f, 287f Longissimus cervicis muscle, 201t Longissimus muscle, 201t, 204, 204f, 205f, 209f, 494f Longissimus thoracis muscle, 201t, 206f Longitudinal arch, 727 Longitudinal fissure, 97f, 99, 101f, 103f, 105f, 128f Longus capitis muscle, 254f, 255f, 260f, 284f, 285f, 286f, 287f, 288f, 289f, 291f, 292f, 293f, 296f, 299f, 300t Longus colli muscle, 255f, 260f, 263f, 266f, 284f, 285f, 287f, 288f, 289f, 290f, 292f, 296f, 300t Loops of Henle, 448 of ileum, 463f of jejunum, 463f of small bowel, 440f Lordotic curve, 173f Low jugular nodes, 282t, 293f Lower extremity, 659–760 Lower extremity lymph vessels, 331f Lower leg arteries of, 752–753, 756f, 757f bony anatomy of, 687–693, 687f, 688f, 710f, 711f, 712f muscles of, 709–717, 715f, 717f, 718f, 718t, 748f nerves of, 759, 760f veins of, 757, 759f Lower paratracheal lymph nodes, 326f Lower pole, of left kidney, 448f, 449f Lower right pulmonary vein, 318f, 362f Lower segmental artery, 474f, 475f

Lower subscapular nerve, 232f, 657f Lumbar artery, 241b, 242f, 245f, 471f, 472f, 473, 555f, 556f, 562f Lumbar nerves, 210f, 223f, 238f Lumbar (para-aortic) nodes, 491f Lumbar pedicle, 186f Lumbar plexus, 760f Lumbar segmental artery, 243f Lumbar spine, 506f Lumbar trunks, of cisterna chyli, 491f Lumbar vein, 388f, 488, 489f Lumbar vertebrae, 173f, 174f, 175f, 185, 187f, 189f, 190f, 191f, 199f, 200f, 201f, 206f, 209f, 210f, 219f, 220f, 222f, 238f, 242f, 245f, 248f, 249f, 395f, 454f, 489f, 493f, 504f Lumbosacral plexus, 228f Lumbrical muscles, 642f, 643f, 645, 647f, 649f, 746f, 748–750, 749f Lumbrical tendon, 746f Lunate bone, 626, 627f, 628f, 630f, 631f, 632f, 633f, 634f, 640f, 644f, 649f Lung cancer, 320b Lungs, 236f, 244f, 315, 315f, 316f, 317f, 318f, 319f, 362f Lunotriquetral ligament, 639f LVOT. see Left ventricular outflow tract Lymph nodes, 491 mediastinal, 328, 328f, 329t, 330f of neck, 265f, 273f, 275f, 278f, 279f, 280, 280f, 281f, 282f, 282t, 290f of pelvis, 565, 566f, 567f Lymph vessels, 331, 331f, 332f Lymphatic system, 328–331 lymph nodes, 328, 328f, 329t, 330f lymph vessels, 331, 331f, 332f

M Main bronchus, 324f Main pancreatic duct, 433–436, 439 Main portal vein, 422f, 439f, 481f Main pulmonary artery, 337f Major calyx, 448, 449f, 450f, 451f Male reproductive organs, 540–552, 540f Malleolar fossa, 692f, 693 Malleolar groove, 687–689, 690f, 693f Malleus, 31f, 33f, 35–37, 35f, 39f, 40f, 43f Mamillary bodies, 101f, 102f, 111f, 112, 112f, 114, 115f, 116f, 119f, 128f, 141f Mamillothalamic tract, 111f Mammary layer, 398f Mandible, 15f, 17f, 24f, 26t, 51f, 53f, 57, 57f, 76f, 171f, 251f, 255f, 256f, 257f, 258f, 265f, 272f, 274f, 276f, 282f, 286f, 296f angle of, 57f, 63f body of, 57, 57f, 289f condylar process of, 34f condyle of, 28f, 286f condyloid process of, 41f, 57f, 58f, 59f, 60f, 63f coronoid process of, 58f ramus of, 26f, 28f, 51f, 54f, 57, 57f, 58f, 63f, 70f, 254f, 258f, 259f, 278f, 296f Mandibular canal, 298f Mandibular condyle, 32f, 33f, 49f, 54f, 59f Mandibular fossa, 30–32, 30f, 32f, 57f, 60, 60f, 61f, 62f Mandibular notch, 49f, 57, 57f, 58f Mandibular rami, 58f, 284f Manubrium, 310, 310f, 311f, 312f, 324f, 328f, 569f, 570f Marginal artery, 486f

Massa intermedia, 90f, 102f, 110, 111f Masseter muscle, 63, 63f, 64f, 65f, 254f, 257f, 258f, 271f, 272f, 274f, 284f, 286f, 287f, 288f, 296f, 298f, 299f, 301f Masticator space, 283f, 284f, 286f, 293t Mastoid air cells, 30f, 31f, 32f, 33f, 34f, 38f, 41f, 45f, 60f, 230f, 254f Mastoid antrum, 30–32, 32f, 33f, 39f, 41f, 42f Mastoid foramen, 16f Mastoid nodes, 280f Mastoid portion, 30f Mastoid process, 15f, 30–32, 30f, 32f, 34f, 45f, 50f, 252f, 254f, 272f, 284f, 286f Mastoid tip, 4f, 41f Maxilla, 15f, 19f, 49f, 50f, 51f, 52f, 53f, 54f, 55f, 69f, 71f, 72f, 74f, 75f, 284f Maxillary bones, 17f, 26t, 50–53 Maxillary sinuses, 28f, 50–53, 51f, 52f, 54f, 58f, 66, 66f, 68f, 69, 69f, 72f, 73f, 75f, 81f, 82f, 84f, 85f, 258f Maximum intensity projection (MIP), 11, 12f Meckel’s cave, 30–32, 34f, 113f, 129f, 163f, 164f, 165f Medial, 3t Medial anterior malleolar artery, 756f Medial basal segmental bronchus, 321f, 322f Medial canthus, 84f Medial circumflex femoral artery, 556f, 752f, 756f Medial collateral ligament, 62f, 688f, 694f, 695f, 696f, 700 Medial condyle, 606f, 610f of humerus, 602f Medial cutaneous nerve, 232f, 600f Medial epicondyle, 574f, 599f, 603f, 606f, 608, 610f, 611f, 614f, 664f, 687f, 689f of humerus, 607f Medial facet, 693f Medial femoral condyle, 687, 688f, 689f, 693f, 694f, 696f Medial geniculate nucleus, 119f Medial inferior genicular artery, 756f, 757f Medial intercondylar tubercle, 687–689, 687f, 696f Medial left lobe, of liver, 414f Medial longitudinal arch, 727 Medial malleolus, 687–689, 690f, 692f Medial margin, 569f Medial meniscus, 694f, 695, 696f, 697f, 705f Medial palpebral ligament, 84f Medial patellar retinaculum, 688f, 697f Medial pectoral nerve, 232f, 657f Medial plantar artery, 757f Medial pterygoid muscle, 63, 63f, 65f, 252f, 254f, 257f, 272f, 284f, 286f, 287f, 288f, 296f Medial pterygoid plate, 23f, 25f, 26f Medial rectus muscle, 77f, 78f, 79f, 81, 82f, 83f, 160f Medial segmental bronchus, 322f Medial superior genicular artery, 756f Medial supracondylar ridge, 574f, 606f Medial tarsal artery, 756f Medial umbilical ligament, 532f Median aperture, 87–91, 90f, 120f of fourth ventricle, 95f Median arcuate ligament, of diaphragm, 420f Median common iliac group, 565 Median cubital vein, 655–656, 656f Median nerve, 232f, 600f, 601f, 602f, 603f, 620f, 637f, 639f, 655f, 657f, 658f Median raphe, 518f, 541f Median sacral artery, 556f, 561f, 563f, 752f Median sacral vein, 489f, 563f, 564f

INDEX Median umbilical ligament, 520f, 521f, 523f, 532f Mediastinal fat, 335, 336f Mediastinum, 314f, 324–327 compartments of, 324, 324f, 324t esophagus, 327, 327f thymus gland, 325, 325b, 325f, 326f trachea, 327, 327f Medulla oblongata, 93f, 95f, 111f, 112f, 119f, 120f, 125, 125f, 126f, 128f, 139f, 168f, 169f, 170f, 218f Medullary pyramid, 119f, 125, 125f, 126f, 130f, 169f Membranous labyrinth, 37f, 38–44 Membranous urethra, 516f, 521, 522f, 540f Memory, loss of, 116b Meniere’s disease, 44b Meningeal grooves, 17f Meningeal vessels, 17f Meninges, 87, 87f, 88f, 89f, 223f Meniscofemoral ligament, 695 Meniscus, 61, 62f Mental foramen, 49f, 51f, 57, 57f Mental protuberance, 49f, 57f Mesencephalon, 120–123 Mesenteric vessels, 484f Mesentery, 400–404, 402f, 466f of small bowel, 407f Mesocolon, 406f, 464f Mesotympanum, 35f, 38, 42f, 43f Metacarpals, 626, 627f, 628f, 629f, 630f, 631f, 637f, 644f, 649f Metacarpophalangeal joint, 628f, 641f, 643f, 644f Metatarsal veins, 759f Metatarsals, 726, 732f, 746f, 750f Metatarsophalangeal joint, 727 Metopic suture, 44–46, 47f, 48f Midbrain, 93f, 95f, 96–97, 97f, 98f, 111f, 117f, 119f, 120–123, 120f, 121f, 125f, 127f, 139f, 144f, 145f, 150f, 154f, 160f Midcarpal joint, 631f, 633, 640f Middle cardiac vein, 352f, 375, 379f Middle cerebellar peduncle, 119f, 123f, 127f, 129f Middle cerebral artery, 97f, 98f, 122f, 130–134, 131f, 131t, 132f, 134f, 134t, 135f, 136f, 137f, 139f, 141f, 143f, 144f, 145f, 306f, 307f Middle colic artery, 482–484, 485f Middle collateral branch, of profunda brachii artery, 600f Middle compartment, of mediastinum, 324, 324t Middle constrictor muscle, 265f, 294, 294t, 295f, 296f Middle cranial fossa, 14–18, 16f, 18t Middle ear, 31f, 35–44, 35f, 36f, 133f, 166f Middle glenohumeral ligament, 573f, 597f Middle hepatic vein, 418f, 420f, 421f, 422f, 424f, 429, 430f, 431f Middle lobe, 316f, 318f, 322f Middle mediastinum, 324f Middle nasal conchae, 21–22, 22f, 52f, 56f, 67f, 68f, 70f, 72f, 85f, 157f, 258f Middle nasal meatus, 22f, 52f, 56f, 67, 67f, 68f, 72f, 73f Middle rectal artery, 556f Middle rectal veins, 564f Middle sacral artery, 488f Middle sacral vein, 488f Middle scalene muscle, 230f, 233f, 234f, 235f, 236f, 270f, 281f, 285f, 292f, 293f, 299f, 300–301, 300t Middle segmental artery, 474f Middle suprarenal artery, 444f, 473f Middle thyroid vein, 303f, 308f

Midjugular nodes, 282t, 290f, 291f, 292f Midtarsal joint, 727 Minor calyx, 448, 449f, 450f, 451f, 452f, 453f MIP. see Maximum intensity projection Mitral valve, 338f, 348, 348f Morison’s pouch, 408, 410f Multifidus muscle, 201t, 202f, 203f, 205–207, 205f, 206f, 207f, 217f, 234f, 285f, 292f Multiplanar reformation, 8–11, 9f, 10f, 11f Mumps virus, in salivary gland, 271b Muscles, 63, 644–646 of abdominal wall, 492–494, 493f, 494f, 495f, 496f, 496t of mastication, 63, 64f, 65f pelvic, 507–518 extrapelvic, 507 pelvic diaphragm, 513 pelvic wall, 510 perineum, 518 thoracic, 391–396 associated with respiration, 391–392, 391f, 391t, 392f, 393f, 394f, 395f, 396f connecting the upper extremity to the anterior and lateral thoracic walls, 396, 396f, 397t Musculocutaneous nerve, 232f, 600f, 657f Mylohyoid muscle, 170f, 255f, 265f, 275f, 276f, 287f, 289f, 290f, 296f, 297f, 298, 298f, 299f, 300t Myocardium, 334f, 336f, 338, 338f, 343f, 348f, 384f Myometrium, 529f, 530f, 531f, 535f, 536f

N Nasal bones, 15f, 17f, 19f, 50, 51f, 52f, 55f, 67f, 71f, 74f, 75f, 251f Nasal cartilage, 251f Nasal meati, 56f Nasal septum, 49f, 54f, 56, 69f, 252f, 284f bony, 22f Nasion, 4f, 48f Nasolacrimal duct, 33f, 54f, 69f, 84, 84f, 85f Naso-orbitoethmoid complex, 22b Nasopharynx, 56f, 251, 251f, 252f, 253f, 254f, 257f, 262f, 286f Navicular bone, 626, 627f, 628f, 630f, 631f, 633f, 719, 721–726, 728f, 731f Neck, 250–308 anterior triangle muscles in, 298, 299f, 300t of bladder, 520f definition of, 250, 250f esophagus, 251f, 252f, 253f, 262f, 267f, 269, 269f, 270f, 292f, 293f, 297f external landmarks of, 4f fascial spaces in, 283, 283f, 284f, 285f of gallbladder, 433–436, 433f, 434f larynx, 251f, 257f, 261–264, 261f, 262f, 263f, 264b, 266f, 267f, 268f, 278f lymph nodes in, 280, 280f, 281f, 282f, 282t of pancreas, 425f, 426f, 433f, 439f, 442f pharynx. see Pharynx posterior triangle muscles in, 298, 299f, 300–301, 300t, 301f trachea, 251f, 252f, 253f, 257f, 258f, 259f, 261f, 262f, 269, 269f, 270f, 278f, 279f, 285f, 292f, 293f, 303f vascular structures of, 302–308, 302t carotid arteries. see also Common carotid artery, 302 vertebral arteries, 257f, 265f, 273f, 279f, 285f, 286f, 287f, 288f, 289f, 290f, 291f, 292f, 293f, 295f, 302, 302t, 303f, 304f, 305f, 306f, 307f

773

Nephron, 448, 451f Nerve rootlets, 230f Neurohypophysis, 112 Nipple, 398f Nipple pores, 397f Nucleus ambiguus, 169f Nucleus pulposus, 177f, 178f, 191f, 198f Nutrient vessels, 244f

O Oblique capitis inferior muscle, 296f Oblique fissure, 318f, 362f Oblique plane, 2, 2f Oblique popliteal ligament, 697f Oblique sinus, 335, 337f, 337t Oblique vein, 352f, 375 Obturator artery, 556f, 558f, 560f, 561f, 562f, 666f, 752f, 756f Obturator canal, 510f, 514f Obturator externus muscle, 504f, 509f, 512f, 513t, 515f, 519f, 523f, 526f, 528f, 530f, 537f, 661f, 662f, 665f, 667f, 668f, 670f, 673, 673f, 674f, 675f, 676f, 676t Obturator foramen, 498f, 499f, 502f, 503f, 506f, 507f, 664f Obturator internus muscle, 239f, 240f, 504f, 509f, 510, 510f, 512f, 513t, 514f, 515f, 517f, 519f, 523f, 526f, 527f, 528f, 530f, 535f, 537f, 539f, 560f, 661f, 662f, 666f, 667f, 670f, 673, 673f, 674f, 675f, 676f, 676t Obturator internus tendon, 512f Obturator nerve, 237f, 759 Obturator nodes, 566f Obturator vein, 564f, 666f Occipital artery, 288f Occipital bone, 14f, 15f, 16f, 17f, 18f, 19f, 20f, 23f, 26t, 27–30, 27f, 28f, 29f, 30f, 33f, 41f, 44f, 45f, 46f, 48f, 49f, 50f, 53f, 54f, 171f, 181f, 194f, 204f, 254f Occipital condyle, 27–30, 27f, 28f, 34f, 41f, 58f, 142f, 180f, 181f, 182f, 196f, 230f Occipital horn, of lateral ventricle, 87–91, 90f, 91f, 92f, 95f, 96f, 104f, 108f, 114f, 115f, 128f, 159f Occipital lobe, 100–105, 100f, 104f, 105f, 114f, 116f, 163f Occipital nodes, 280f Occipital sinus, 146f Occipital vein, 308f Occipitomastoid suture, 14f, 15f, 17f, 18f, 38f, 44–46, 44f, 45f, 48f Oculomotor nerve, 111f, 119f, 150f, 152f, 156f, 156t, 160, 160f, 161f, 162f Odontoid process, 27f, 179f, 180f, 181f, 182f, 194f, 195f, 196f, 197f, 225f, 233f, 235f, 254f, 272f, 286f Olecranon, 611f Olecranon bursa, 610, 610f Olecranon fossa, 574f, 606f, 608, 610f Olecranon process, 605f, 607f, 609, 609f, 610f, 614f, 615f, 623f of ulna, 605f Olfactory bulb, 88f, 115f, 141f, 156f, 157f Olfactory foramina, 21f Olfactory nerve, 156f, 156t, 157, 157f, 158f Olfactory nerve fibers, 157, 157f Olfactory tracts, 88f, 114, 115f, 118f, 141f, 157f Olive, 119f, 125, 125f, 126f, 169f, 170f medullary, 169f Omohyoid muscle, 291f, 292f, 298, 299f, 300t

774

INDEX

OMU. see Osteomeatal unit Ophthalmic artery, 79, 82f, 83f, 130, 131f, 134f, 134t, 139f, 150f Ophthalmic veins, 153 Opponens digiti minimi muscle, 637f, 646, 648f, 750f Opponens pollicis muscle, 646, 647f, 648f, 649f Optic canal, 14f, 23–25, 23f, 24f, 51f, 70f, 73, 74f, 75f, 76f, 77f Optic chiasm, 70f, 110f, 111f, 112, 113f, 119f, 132f, 158–160, 159f, 160f Optic foramen, 73 Optic groove, 23f Optic nerve, 77f, 78f, 79, 81f, 82f, 83f, 88f, 111f, 112f, 119f, 141f, 150f, 156f, 156t, 158–160, 158f, 159f, 160f, 161f Optic radiations, 105f, 158–160, 159f Optic strut, 14f, 23–25, 70f, 73, 74f, 76f Optic tract, 94f, 101f, 116f, 119f, 122f, 139f, 158–160, 159f, 160f Oral cavity, 251f Orbicularis oculi muscle, 301f Orbicularis oris muscle, 301f Orbit, 73–84 axial computed tomography of, 78f, 80f axial view of, 79f blowout fracture of, 77b bony, 73, 74f coronal computed tomography of, 82f coronal view of, 82f floor of, 72f, 73, 74f lateral wall of, 72f, 73, 74f, 75f magnetic resonance imaging of, 78f, 81f, 83f medial wall of, 72f, 73, 74f, 75f roof of, 72f, 74f sagittal view of, 51f, 75f, 81f soft tissue structures of, 77 Orbital fissure, 23–25 Orbital plate, 18, 20f, 21f, 22f, 51f, 72f, 74f, 75f, 85f Orbitofrontal artery, 130, 133f Orifice, of appendix, 460f Oropharynx, 251–256, 251f, 252f, 253f, 255f, 257f, 258f, 259f, 262f, 265f, 275f, 278f, 287f, 296f, 297f Osteomeatal unit (OMU), 72–73, 72f Oval window, 35f, 37f, 38–44, 40f, 42f, 166f Ovarian artery, 488f, 556f, 563f Ovarian ligament, 530f, 532f, 533f, 537f, 539f Ovarian vein, 563f Ovary, 520f, 523f, 525f, 529f, 530f, 531f, 532f, 533f, 535, 535f, 536f, 537f, 539f, 566f

P Palatine bones, 17f, 50, 50f, 51f, 53f, 69f, 75f Palatine process, 50–53, 50f, 52f, 53f Palatine tonsil, 251–256, 251f, 252f, 258f, 259f, 288f, 296f Palatoglossus muscle, 294, 294t Palatopharyngeal space, 287f Palatopharyngeus muscle, 255f, 256f, 265f, 275f, 294, 294t, 296f Palmar, 3t Palmar carpal arch, 651–655, 652f, 655f Palmar digital artery, 643f Palmar digital nerve, 643f Palmar interosseous muscle, 642f, 647f, 648f, 649f Palmar ligament, 641f, 643f

Palmar metacarpal artery, 653f Palmar plate, 643f Palmar radial carpal ligaments, 635–636 Palmar radioulnar ligament, 635f Palmaris longus muscle, 611f, 616t, 617, 617f, 618f, 619f, 622f, 647f Pampiniform plexus, 541f, 542f Pancreas, 401f, 402f, 403f, 405f, 406f, 409f, 410f, 412f, 415f, 422f, 425f, 428f, 433f, 435f, 439, 444f, 447f, 458f, 459f, 461f, 463f, 477f, 481f, 483f, 486f, 490f Pancreatic duct, 433f, 434f, 442f, 465f Pancreatic tail, 442f, 447f Pancreaticoduodenal vein, 564f Papillary muscles, 338–339, 338f, 343f, 345f, 350f, 376f, 382f, 384f Paracolic gutter, 407f, 411t Parahippocampal gyrus, 100–105, 101f, 115f Paranasal sinuses, 66–73, 66f drainage of, 68t ethmoid sinuses. see Ethmoid sinuses frontal sinuses. see Frontal sinuses maxillary sinuses. see Maxillary sinuses sphenoid sinuses. see Sphenoid sinuses Parapharyngeal space, 283f, 284f, 286f, 287f, 293t Paraplegia, 229b Pararenal fat, 449f Pararenal spaces, 411t Paraspinal space, 285f, 288f, 293t Parathyroid gland, 261f, 277, 277f, 303f Paraventricular nucleus, 111f Parietal bone, 14f, 15f, 17f, 18, 24f, 44f Parietal eminence, 15f, 18, 18f Parietal lobe, 100–105, 100f, 101f, 105f, 106f, 147f Parietal pericardium, 335f Parietal peritoneum, 400f, 402f Parietal pleura, 314, 314f Parietomastoid suture, 14f, 15f, 18f, 44–46, 44f Parieto-occipital artery, 133f Parkinson disease, 123b Parotid duct, 271, 271f, 272f, 286f Parotid gland, 233f, 235f, 252f, 254f, 258f, 259f, 271, 271f, 272f, 273f, 278f, 284f, 286f, 287f, 288f, 296f Parotid nodes, 280f Parotid space, 283f, 284f, 287f, 288f, 293t Pars interarticularis, 182f, 188–189f, 189f Patella, 677f, 678f, 687f, 688f, 690f, 691f, 692f, 693, 693f Patellar articular cartilage, 691f Patellar ligament, 677–679, 677f, 678f, 688f, 690f, 691f, 692f, 700, 707f Patellar retinaculum, 700 Patellofemoral joint, 688f, 693, 693f, 706f Pectineal line, 498f, 499f, 503f, 506f, 661, 664f Pectineus muscle, 208f, 510f, 512f, 514f, 515f, 519f, 526f, 528f, 539f, 559f, 674f, 675f, 676f, 677f, 678f, 683, 755f Pectoralis major muscle, 236f, 392f, 396, 396f, 397f, 397t, 398f, 495f, 589f, 597f, 598, 598f, 599t, 602f, 654f Pectoralis minor muscle, 392f, 396, 396f, 397f, 397t, 589f, 597f, 598, 598f, 599t, 602f, 654f Pectum, 501f Pedicle, 174f, 175f, 182f, 185f, 188–189f, 189f, 190f, 198f, 215f, 219f, 221f, 238f Pelvic brim, 503f, 506, 506f, 507f Pelvic diaphragm, 513, 513f, 513t, 514f, 515f, 516f, 517f Pelvic division, 4–6

Pelvic inlet, 506, 506f, 507f Pelvic outlet, 506, 506f, 507f Pelvic spaces, 539 Pelvic wall muscles, 508f, 509f, 510, 510f, 511f, 512f, 513t Pelvis, 400f, 497–567, 497f lymph nodes, 565 muscles, 507–518 vasculature, 555–565 viscera, 520–552 Penile urethra, 516f, 521, 522f, 540f Penis, 522f, 540f, 541f, 552, 552f, 553f, 554f root of, 522f Perforating arteries, 752, 756f Perforating branch of peroneal (fibular) artery, 756f of profundus femoris, 755f Periaqueductal gray matter, 120–123, 121f, 122f Pericallosal artery, 130, 131f, 133f, 134f Pericardial cavity, 314f, 335, 335f Pericardial recess, 337f, 337t Pericarditis, 335b Pericardium, 334f, 335, 335f, 336f, 337f, 337t, 340f, 341f, 349f Perimetrium, 529–530, 530f, 535f Perineal body, 516f, 518, 518b, 518f Perineal membrane, 516f, 517f, 518, 520f, 522f, 523f, 529f, 537f Perineum, 518, 518f Peripheral pulmonary arteries, 356f Peripheral zone, 549 Perirenal fat, 444–445, 445f, 447f, 448, 449f, 452f, 453f Perirenal space, 411t, 412f, 413f Peritoneal cavity, 402f Peritoneal ligaments, 404, 408t Peritoneal space, 408, 411t Peritoneum, 400–404, 401f, 402f, 523f Peritonitis, 404b Perivertebral space, 283f, 285f, 288f, 289f, 293t Peroneal artery, 753, 757f Peroneal nerve, 237f Peroneal retinaculum, 734 Peroneus brevis muscle, 692f, 715, 748f Peroneus fibularis muscle, 696f Peroneus longus muscle, 691f, 715, 748f Peroneus longus tendon, 692f Peroneus tertius muscle, 715 Perpendicular plate, 21–22, 21f, 22f, 85f of ethmoid, 19f, 21f, 49f, 52f, 71f Pes anserinus bursa, 709 Petro-occipital fissure, 30–32, 30f, 33f Petrosal sinuses, 150f, 153 Phalanges of foot, 726 of hand, 626 Pharyngeal constrictor muscle, 265f, 285f, 287f Pharyngeal mucosal space, 287f, 288f, 293t Pharyngeal tonsil, 251, 251f, 252f, 253f, 258f, 262f, 297f Pharynx. see also Laryngopharynx, 253, 181f, 251–256, 251f, 252f, 253f Phrenic nerve, 229, 229b, 231f, 285f Phrenicocolic ligament, 407f Phrenocolic ligament, 408t Pia mater, 87, 87f, 210–212, 213f, 221f Pineal gland, 102f, 109f, 111f, 112f, 114, 114f, 119f, 120f, 121f, 126f, 153f calcified, 115f Piriform sinuses, 252f, 256, 257f, 258f, 259f, 260f, 263f, 264

INDEX Piriformis muscle, 208f, 237f, 239f, 240f, 470f, 508f, 509f, 510f, 513t, 517f, 539f, 668f, 673, 673f, 674f, 676t Pisiform bone, 626, 627f, 628f, 629f, 630f, 633f, 640f, 649f Pituitary gland, 29f, 67f, 70f, 110f, 111f, 112, 112f, 113f, 114f, 124f, 125f, 128f, 132f, 141f, 150f, 151f, 152f, 157f, 158f, 161f, 258f Pixel, 7f Plantar, 3t Plantar arch, 759f Plantar fascia, 734, 750f Plantar interosseous I, 750f Plantar interosseous II, 750f Plantar interosseous III, 750f Plantar plate, 746, 746f Plantar veins, 759f Plantaris muscle, 716 Plantaris tendon, 692f Platysma muscle, 258f, 260f, 263f, 266f, 275f, 285f, 289f, 290f, 291f, 298, 298f, 299f, 301f Pleural cavities, 314, 314f Pleural effusion, 314f Pons, 29f, 37f, 93f, 94f, 95f, 98f, 99f, 100f, 111f, 112f, 114f, 118f, 119f, 120f, 123, 123f, 124f, 125f, 127f, 128f, 129f, 132f, 133f, 139f, 150f, 160f, 163f, 164f, 165f, 167f, 170f, 218f Pontine arteries, 139f, 141f, 142f, 145f Pontine vessels, 138, 145t Popliteal artery, 679f, 682f, 690f, 691f, 753, 756f, 757f, 758f Popliteal fossa, 673f Popliteal ligament, 700 Popliteal surface, 687 Popliteal vein, 679f, 690f, 691f, 757, 758f, 759f Popliteus bursa, 709 Popliteus muscle, 691f, 708f, 717 Popliteus tendon, 694f Porta hepatis, 414f, 415, 424 Portal hepatic system, 424, 424f, 425f, 426f, 427f Portal hypertension, 424b Portal splenic confluence, 424f, 426f, 427f, 439 Portal vein, 400f, 401f, 414f, 415f, 416f, 417f, 418f, 419f, 422f, 423f, 424f, 425f, 426f, 427f, 428f, 429f, 432f, 433f, 435f, 436f, 437f, 438f, 442f, 443f, 447f, 463f, 477f, 478f, 564f Postcaval recess, 337f Postcentral gyrus, 99, 100f Posterior, 3t Posterior abdominal wall, 449f Posterior acetabular labrum, 668f, 669f, 671f Posterior aortic sinus, 353f, 372f, 373f Posterior arch, 179f, 181f, 184f, 194f, 197f Posterior atlantooccipital membrane, 194, 194f, 195f Posterior atrioventricular groove, 352f Posterior cardiac vein, 375 Posterior cecal artery, 485f Posterior central vein, 246, 246f Posterior cerebral artery, 98f, 131f, 134f, 135f, 136f, 138, 139f, 141f, 142f, 143f, 144f, 145f, 145t, 161f, 242f segments of, 138t Posterior cervical space, 290f, 293f, 293t Posterior clinoid process, 23–25, 23f, 24f, 34f Posterior column, 661f, 669f, 671f Posterior commissure, 100, 102f, 104f, 111f, 112f, 114f, 118f

Posterior communicating artery, 131f, 137f, 138, 139f, 141f, 143f, 144f, 145f Posterior compartment, of mediastinum, 324, 324t Posterior cranial fossa, 14–18, 16f, 18t Posterior cricoarytenoid muscle, 263f Posterior cruciate ligament, 688f, 690f, 691f, 694f, 695f, 696f, 700, 704f, 707f Posterior cutaneous nerve, 600f Posterior descending artery, 370–371, 370f Posterior digastric muscle, 252f Posterior ethmoid air cell, 21f, 56f, 67f Posterior ethmoid sinus, 55f, 66f Posterior external venous plexuses, 246, 246f, 247f Posterior fat pad, 608f, 609f, 610f, 612f, 623f Posterior femoral cutaneous nerve, 237f Posterior fontanel, 47 Posterior fornix, 516f, 529f Posterior glenoid joint capsule, 583f Posterior glenoid labrum, 592f Posterior humeral circumflex artery, 593f, 604f Posterior inferior cerebellar artery, 131f, 133f, 135f, 138, 139f, 141f, 142f, 145f, 145t, 160f, 242f Posterior inferior iliac spine, 502f, 503f Posterior intercostal veins, 388f Posterior internal venous plexus, 246f, 247f Posterior interosseous artery, 652f Posterior interventricular artery, 352f Posterior interventricular branch, 370–371 Posterior longitudinal ligament, 178f, 191f, 194–196, 194f, 195f, 198f, 199f, 200f, 201f, 226f, 247f Posterior median fissure, 119f, 125, 125f Posterior median sulcus, 213f, 214, 223f, 244f Posterior median veins, 246, 246f Posterior mediastinum, 324f Posterior meniscofemoral ligament, 694f, 695, 696f Posterior nucleus, 111f Posterior pararenal space, 412, 412f, 413f Posterior pericardial recess, 337f Posterior pericardium, 324f Posterior plexiform network, 244f Posterior radicular artery, 241, 244f Posterior radicular vein, 246, 246f Posterior ramus, 485f Posterior scalene muscle, 233f, 234f, 270f, 285f, 289f, 292f, 293f, 299f, 300–301, 300t Posterior segmental bronchus, 320f, 321f, 322f Posterior semicircular canal, 35f, 39f, 40f, 41f Posterior semicircular duct, 37f Posterior serratus muscles, 392f Posterior spinal artery, 241, 244f Posterior superior iliac spine, 204f, 502f, 503f Posterior superior pancreatic duodenal artery, 439f, 481f Posterior talofibular ligament, 692f Posterior thecal sac, 184f Posterior tibial artery, 753, 757f Posterior tibial vein, 757 Posterior tibiofibular ligament, 692f Posterior triangle lymph nodes, 281f, 282t, 289f, 293f Posterior triangle muscles, 298, 299f, 300– 301, 300t, 301f Posterior ulnar recurrent artery, 651, 652f Posterolateral fontanel, 47, 48f Posterolateral sulcus, 213f, 214, 223f

775

Posttraumatic fractures, of thoracic spine, 172f Preaortic nodes, 566f Precentral gyrus, 99, 100f Pre-epiglottic space, 262f Preoptic nucleus, 111f Prepatellar bursa, 709 Prepontine cistern, 95f, 96–97, 98f, 114f, 124f Presacral space, 539f Pretracheal space, 283f Prevertebral space, 283f, 285f, 288f, 293t Profunda brachial artery, 603f, 650–651f Profunda brachii artery, 600f Profunda femoris artery, 678f, 752, 752f, 756f, 759f Profunda femoris vein, 759f Pronator quadratus muscle, 616t, 618f, 624, 624f, 634f, 640f, 644f Pronator teres muscle, 611f, 612f, 613f, 614f, 615f, 616t, 617, 618f, 619f, 620f, 622f, 623f Proper hepatic artery, 428f, 430f, 439f, 477f, 479f, 480, 480f, 481f, 485f, 487f Proper palmar digital artery, 653f Prostate cancer, 549b Prostate gland, 512f, 514f, 515f, 516f, 517f, 519f, 522f, 526f, 527f, 540f, 548f, 549, 549f, 550f, 551f, 558f, 559f, 564f Prostatic urethra, 515f, 521, 522f, 526f, 540f Prostatic venous plexus, 564f Proximal, 3t Proximal interphalangeal joint, 627f Proximal left portal vein, 422f Proximal radioulnar joint, 607f Proximal radius, 608, 608b, 608f Proximal tibiofibular joint, 690f Prussak space, 35f, 37, 39f, 42f Psoas major muscle, 208f, 493f, 510f, 674f, 675f, 677 Psoas minor muscle, 208f, 493f Psoas muscle, 205–207, 208f, 209f, 215f, 220f, 222f, 237f, 238f, 248f, 249f, 407f, 413f, 448f, 450f, 452f, 454f, 466f, 476f, 484f, 492–494, 494f, 496t, 499f, 500f, 507, 510f, 511f, 537f, 541f, 556f, 557f Pterion, 14f, 15f, 18f, 44–46, 44f, 46b Pterygoid canal, 23–25, 25f, 26f, 76f Pterygoid hamulus, 23–25, 23f, 25f, 26f, 58f, 295f Pterygoid muscles, 65f Pterygoid plates, 23–25, 27f, 51f, 75f Pterygoid process, 23–25, 26f, 28f, 33f, 50f, 53f, 54f, 58f, 65f, 69f, 76f Pterygoid venous plexus, 308f Pterygomaxillary fissure, 33f, 54f, 69f Pterygomaxillary fossa, 69f Pterygopalatine fossa, 28f, 50, 51f, 54f, 75f Pubic bone, 504f, 519f, 522f, 540f Pubic ramus, 559f Pubic symphysis, 400f, 495f, 498f, 499f, 503f, 505f, 506f, 510f, 515f, 516f, 518f, 519f, 520f, 522f, 526f, 528f, 529f, 539f, 664f Pubic tubercle, 208f, 493f, 495f, 498f, 499f, 510f Pubis, 498, 502f, 503f, 507f, 513f, 537f, 539f, 660, 663f, 665f Pubococcygeus muscle, 513, 513f Pubofemoral ligament, 665, 665f, 670f Puboprostatic ligament, 515f Puborectalis muscle, 513, 513f Pubovesical ligament, 515f, 539f Pudendal nerve, 237f, 760f Pulmonary artery, 231f, 323f, 324f, 348f

776

INDEX

Pulmonary embolism, 360b Pulmonary ligament, 318f, 362f, 363f Pulmonary semilunar valve, 333f, 334f, 348, 348f, 349f, 363f, 374f, 387f Pulmonary sinuses, 352, 353f Pulmonary trunk, 311f, 317f, 319f, 325f, 326f, 334f, 337f, 339f, 340f, 346f, 349f, 350f, 351f, 352, 353f, 356f, 357f, 359f, 360f, 361f, 363f, 369f, 372f, 373f, 374f, 375f, 381f, 383f, 384f, 385f, 386f, 387f, 394f Pulmonary veins, 231f, 323f, 325f, 339f, 348f, 353–357, 386f Putamen, 101f, 106, 108f, 109f Pyloric antrum, 455, 455f, 459f, 469f Pyloric canal, 455f Pyloric orifice, 455f Pyloric sphincter, 455, 455f, 456f, 459f, 461f, 469f

Q Quadrants, of abdomen, 4, 6, 6f, 7t Quadrate lobe, of liver, 415, 417f Quadratus femoris muscle, 241f, 512f, 559f, 668f, 673f, 674f, 675f, 676, 676t, 677–679, 677f, 678f, 755f Quadratus lumborum muscle, 205–207, 207f, 208f, 209f, 492–494, 493f, 494f, 496t, 677f Quadratus plantae muscle, 745f, 748–750 Quadriceps femoris tendon, 694f, 697f Quadriceps tendon, 677–679, 690f, 691f, 695f, 706f, 758f Quadrigeminal cistern, 95f, 96–97, 97f, 107f, 122f, 136f, 144f, 162f Quadrigeminal plate, 96–97, 97f, 120–123 Quadriplegia, 229b

R Radial artery, 621f, 650–651f, 651, 652f, 653f, 654f, 655f, 658f Radial collateral arteries, 600f Radial collateral ligament, 611f, 613f, 614f, 622f Radial dorsal tubercle, 607f, 609 Radial fossa, 574f, 606f, 608f Radial groove, 574f, 606f Radial head, 606f, 607f, 608, 608f, 611f, 613f, 615f, 622f, 623f Radial neck, 608, 608f Radial nerve, 232f, 600f, 601f, 602f, 603f, 639f, 657f Radial notch, 606f, 607f, 609, 611f, 615f Radial recurrent artery, 650–651f, 651 Radial styloid process, 607f Radial tuberosity, 599f, 606f, 607f, 608, 614f, 622f Radial veins, 246, 246f, 654f, 655f, 656f Radicular vessels, 215f Radiocarpal joints, 631f, 632f, 634f Radiohumeral articulation, 606, 606f Radiolunate ligament, 635f, 644f Radioscaphocapitate ligament, 634f, 635f Radioulnar articulation, 606, 606f Radius, 232f, 599f, 605f, 607f, 608, 608f, 628f, 632f, 640f, 644f, 652f, 654f, 655f Ray tracing, 8, 11f Recesses, 335 of pleural cavities, 314 Rectal artery, 560f Rectal column, 527f

Rectal fascia, 539f Rectal venous plexus, 564f Rectouterine pouch, 521f, 529f, 532f, 533f, 539f Rectovesical pouch, 540f Rectum, 402f, 404f, 424f, 460f, 464f, 467f, 513f, 514f, 516f, 517f, 519f, 521f, 522f, 525f, 526f, 527, 527f, 528f, 529f, 531f, 532f, 533f, 534f, 536f, 538f, 539f, 540f, 558f, 559f, 560f, 564f Rectus abdominis muscle, 492–494, 493f, 494f, 495f, 496t, 499f, 507, 508f, 509f, 511f, 525f, 526f, 528f, 541f, 558f, 559f, 674f, 675f Rectus capitis anterior muscle, 286f Rectus capitis muscle, 287f Rectus capitis posterior major muscle, 207f Rectus capitis posterior minor muscle, 207f Rectus femoris muscle, 241f, 512f, 661f, 666f, 674f, 675f, 676f, 682f, 755f Rectus muscle, 81, 83f Rectus sheath, 495f Red nucleus, 111f, 120–123, 121f, 122f Red pulp, of spleen, 443, 444f Regional terminology, 3t, 4f Renal agenesis, 451b Renal artery, 245f, 444f, 473, 473f, 474f anterior division of, 475f stenosis, 473b Renal columns, 451f Renal cortex, 449f, 450f, 451f, 452f, 453f Renal fascia (Gerota’s fascia), 412f, 413f, 444–445, 448–451, 449f, 452f, 453f Renal hilum, 452f, 453f Renal impression, 414f Renal medulla, 448, 451f, 453f Renal papilla, 451f Renal pelvis, 448, 449f, 450f, 451f, 452f, 453f Renal pyramid, 448, 449f, 450f, 451f, 452f, 453f Renal sinus, 448, 449f Renal vein, 444f, 474f, 489f, 490, 564f Rete testis, 542, 542f Reticular formation, 119, 120f Retina, 77f, 78f, 158–160, 159f Retromammary layer, 398f Retromandibular vein, 272f, 276f, 286f, 287f, 288f, 308f Retroorbital fat, 77f, 78f, 79, 79f, 80f, 81f, 82f, 83f, 159f Retroperitoneal spaces, 411t, 412 Retroperitoneum, 400f, 401f, 412 Retropharyngeal nodes, 282t Retropharyngeal space, 260f, 283f, 285f, 289f, 290f, 291f, 292f, 293t Retropubic space, 515f, 516f, 522f, 526f, 529f, 539, 539f Retrovisceral space, 283f Rhomboid major muscle, 587f, 589f, 590t Rhomboid minor muscle, 587f, 590t Rhomboid muscle, 301f, 392f Ribs, 185f, 186f, 187f, 188–189f, 200f, 202f, 206f, 226f, 230f, 244f, 310, 310f, 313f, 324f, 341f, 393f, 432f, 495f, 570f, 602f Right adrenal gland, 413f, 421f, 444–445, 444f, 445f, 446f, 447f, 450f, 452f, 458f, 482f Right aorta, 347f Right aortic sinus, 350f, 370–371, 372f, 373f Right ascending pulmonary artery, 356f, 358f, 359f Right atrial appendage, 339f, 345f, 351f, 361f, 371f, 372f Right atrioventricular valve, 338f, 348, 348f

Right atrium, 231f, 311f, 312f, 334f, 338–339, 338f, 339f, 340f, 341f, 342f, 343f, 344f, 346f, 348f, 349f, 350f, 351f, 352f, 356f, 359f, 361f, 362f, 364f, 369f, 370f, 371f, 373f, 374f, 376f, 377f, 379f, 380f, 381f, 382f, 383f, 384f, 387f, 389f, 394f, 427f, 432f, 440f Right auricle, 379f Right brachiocephalic vein, 303f, 325f, 327f, 331f, 351f, 352f, 365f, 367f, 368f, 369f, 370f, 379f, 394f Right bundle branch, 338f Right clavicle, 569f Right colic artery, 482–484, 485f Right colic flexure, 460f, 464f Right common carotid artery, 280f, 302, 302t, 304f, 305f, 325f, 358f, 365, 365f, 366f, 368f, 370f Right common iliac artery, 454f, 471f, 475f, 485f, 494f, 555f, 556f, 561f, 562f, 566f Right common iliac vein, 564f Right coronary artery, 339f, 346f, 350f, 351f, 352f, 361f, 370–371, 370f, 371f, 372f, 373f, 376f, 377f, 378f, 381f, 382f, 383f, 387f Right crus of diaphragm, 332f, 394f, 395f, 396f, 428f, 445f, 446f, 447f, 452f, 471f, 478f, 482f, 493f Right descending pulmonary artery, 356f, 358f, 359f Right external carotid artery, 304f Right external iliac artery, 471f, 475f, 523f, 555f, 561f Right external iliac vein, 523f Right gastric artery, 428f, 477f, 480, 480f Right gastric vein, 564f Right gastroepiploic artery, 428f, 477f, 480 Right gonadal artery, 471f, 476f, 479f, 486f, 555f Right gonadal vein, 476f, 489f, 490 Right hepatic artery, 428, 428f, 429f, 430f, 439f, 472f, 477f, 480f, 481f Right hepatic duct, 433f, 434f, 437f Right hepatic vein, 418f, 419f, 420f, 421f, 422f, 424f, 427f, 429, 430f, 431f, 432f Right horizontal fissure, 315f Right inferior epigastric artery, 523f Right inferior lobe, 315f, 316f, 317f, 320f, 321f, 341f, 362f Right inferior lobe bronchus, 321f Right inferior phrenic artery, 472f, 475f Right inferior phrenic vein, 488, 488f Right inferior pubic ramus, 506f Right inferior pulmonary vein, 312f, 341f, 342f, 351f, 352f, 353–357, 356f, 358f, 359f, 361f, 362f, 368f, 372f Right infracolic space, 408, 408f, 411f Right inguinal ligament, 471f, 555f Right intermediate bronchus, 337f Right internal carotid artery, 304f Right internal iliac artery, 471f, 475f, 555f, 561f anterior trunk of, 561f posterior trunk of, 561f Right internal jugular vein, 278f, 331f, 365f, 369f Right internal thoracic artery, 365, 366f, 367f, 368f Right internal thoracic vein, 368f, 379f Right jugular trunk, 331f Right kidney, 410f, 412f, 413f, 422f, 436f, 437f, 442f, 445f, 446f, 447f, 448f, 450f, 472f, 496f segments of, 453f Right lateral circumflex femoral artery, 755f

INDEX Right lobe, of liver, 406f, 407f, 414f, 415, 415f, 416f, 417f, 418f, 427f, 428f, 432f, 436f, 456f, 457f, 465f anterior segment of, 422f inferior anterior segment of, 430f inferior posterior segment of, 430f posterior segment of, 422f superior anterior segment of, 430f superior posterior segment of, 430f Right lower quadrant, 6, 6f, 7t Right lumbar (retro-caval) nodes, 491f Right lumbar trunks, 331f Right lung, 243f, 314f, 319f, 330f, 385f Right lymphatic duct, 331, 331f Right main portal vein, 424f, 427f Right mainstem bronchus, 315f, 317f, 318f, 319f, 320, 320f, 321f, 355f, 356f, 357f, 360f, 362f, 389f Right marginal artery, 351f Right marginal branch, 370–371, 373f Right middle lobe, 341f, 362f Right middle lobe bronchus, 321f Right oblique fissure, 315f, 316f, 317f, 320f Right ovarian vein, 564f Right ovary, 404f Right paracolic gutter, 408, 408f, 411f Right perirenal space, 413f Right phrenic nerve, 231f Right portal vein, 418f, 419f, 421f, 422f, 564f anterior branches of, 421f, 422f posterior branches of, 422f, 423f Right psoas muscle, 445f Right pulmonary arteries, 231f, 311f, 317f, 318f, 319f, 337f, 339f, 346f, 347f, 351f, 352, 352f, 355f, 356f, 357f, 358f, 359f, 360f, 362f, 364f, 368f, 370f, 379f, 385f Right pulmonary veins, 340f, 379f Right pulmonary venous recess, 337f Right pulmonic recess, 337f, 337t Right renal artery, 471f, 472f, 474f, 475f, 479f, 485f, 486f, 555f, 561f Right renal pelvis, 453f Right renal vein, 440f, 442f, 448f, 488f, 490, 490f, 563f, 564f Right subclavian artery, 318f, 362f, 365f, 366f, 368f, 370f Right subclavian trunk, 331f Right subclavian vein, 233f, 331f, 365f, 369f Right subhepatic space, 403f, 407f, 408f, 410f Right subphrenic space, 408f, 409f, 410f Right superior lobe, 315f, 316f, 317f, 320f, 362f Right superior lobe bronchus, 315f, 317f, 320f, 321f, 360f Right superior pulmonary vein, 318f, 337f, 351f, 352f, 353–357, 356f, 358f, 360f, 361f, 362f, 372f, 374f Right suprarenal artery, 471f, 555f Right suprarenal vein, 489f, 491 Right testicular vein, 564f Right triangular ligament, 414f Right upper quadrant, 6, 6f, 7t Right ureter, 454f, 476f, 523f, 524f Right uterine tube, 404f Right vagus nerve, 231f Right vas deferens, 523f Right ventricle, 231f, 311f, 312f, 334f, 336f, 338–339, 338f, 339f, 340f, 341f, 342f, 343f, 344f, 345f, 346f, 347f, 348f, 349f, 350f, 351f, 352f, 353f, 355f, 362f, 363f, 364f, 370f, 371f, 372f, 373f, 375f, 376f, 377f, 378f, 379f, 380f, 381f, 382f, 384f, 386f, 387f, 420f

Right ventricular outflow tract (RVOT), 346f, 380–382, 383f, 386f Right vertebral artery, 233f Rostral, 3t Rostrum, of corpus callosum, 99, 102f Rotator cuff, 590, 590b Rotator cuff muscles, 597f Rotatores muscles, 201t, 205–207, 205f, 207f Round ligament, 404, 408t, 414f, 418f, 531f, 532f, 533f, 539f of liver, 564f Round window, 35f, 37f, 38–44, 40f, 42f, 166f Rugae, 455, 455f, 456f, 457f RVOT. see Right ventricular outflow tract

S Saccular duct, 37f Saccule, 37f Sacral ala, 454f, 558f Sacral canal, 193f Sacral cornu, 173f Sacral flexure, 520f Sacral foramina, 187f, 191, 192f, 498f, 499f, 500f, 501f, 664f Sacral hiatus, 173f Sacral nerves, 210f, 223f, 224f, 238f, 239f, 500f Sacral nodes, 566f Sacral plexus, 237f, 760f Sacral promontory, 187f, 188–189f, 192f, 193f, 215f, 400f, 498, 499f, 500f, 506f, 507f, 664f Sacroiliac joint, 191, 192f, 193f, 208f, 224f, 238f, 239f, 498f, 499f, 500f, 501f, 511f, 558f, 664f Sacrotuberous ligament, 514f, 518f Sacrum, 173f, 187f, 188–189f, 191, 192f, 193f, 204f, 212f, 222f, 224f, 237f, 238f, 239f, 242f, 470f, 498–500, 498f, 499f, 500f, 501f, 502f, 506f, 507f, 508f, 509f, 510f, 511f, 513f, 517f, 518f, 522f, 557f, 560f, 673f Sagittal plane, 2, 2f Sagittal suture, 18f, 44–46, 44f, 47f, 48f Salivary glands, 271, 271f parotid gland, 252f, 254f, 258f, 259f, 271, 271f, 272f, 273f, 278f, 284f, 286f, 287f, 288f, 296f sublingual glands, 271, 271f, 276f, 297f, 298f submandibular glands, 252f, 255f, 256f, 257f, 258f, 259f, 265f, 271, 271f, 274f, 275f, 276f, 280f, 281f, 282f, 289f, 290f, 298f Salpingopharyngeus muscle, 294, 294t Saphenous nerve, 229, 237f, 679f, 759, 760f Saphenous vein, 690f, 759f Sartorius muscle, 510f, 512f, 514f, 559f, 661f, 666f, 674f, 675f, 676f, 677, 677f, 680f, 682f, 688f, 690f, 755f, 758f Sartorius tendon, 691f Scala tympani, 37f Scala vestibuli, 37f Scalene muscles, 236f, 270f, 290f, 396f Scaphoid bone, 626, 627f, 628f, 629f, 630f, 631f, 633f, 634f, 639f, 640f, 649f Scapholunate ligament, 634f, 639f Scapula, 233f, 301f, 367f, 569f, 570–572, 570f, 571f, 572f, 573f, 581f, 583f, 585f, 587f, 588f, 589f, 590, 596f, 597f, 598f, 599f, 602f, 605f Scapular notch, 569f, 570–572, 571f, 572f

777

Scapular spine, 569f, 571f, 572f, 573f, 574f, 580f, 582f, 588f, 591f, 605f Schizophrenia, gray matter and, 105b Sciatic nerve, 229, 237f, 240f, 241f, 661f, 666f, 679f, 759, 760f Scoliosis, 173b Scrotal septum, 541f Scrotal skin, 541f Scrotum, 518f, 522f, 540–541, 540f, 541f Scutum, 35f, 37, 42f Second lumbar vein, 489f Second metatarsal, 746f Secondary bronchi, 320 Secondary pulmonary lobule, 320, 323f Sectional anatomy, introduction to, 1f Segmental artery, 238f, 241b, 244f, 245f Segmental bronchi, 320, 323f Segmental pulmonary veins, 323f Sella turcica, 16f, 17f, 19f, 23–25, 23f, 24f, 29f, 51f, 56f, 70, 75f, 99f, 112 Semicircular canals, 31f, 34f, 35f, 36f, 37f, 38–44, 41f, 166f, 167f Semicircular duct, 31f Semilunar hiatus, 72–73, 72f, 73f Semilunar notch, 607f Semilunar valves, 348, 350f Semimembranosus bursa, 709 Semimembranosus muscle, 673f, 674f, 679f, 682f, 687, 697f, 758f Semimembranosus tendon, 680f, 688f, 694f, 705f Seminal vesicle, 516f, 522f, 525f, 527f, 540f, 547, 547f, 548f Seminiferous tubules, 542, 542f Semispinalis capitis muscle, 201t, 202f, 203f, 204f, 234f, 255f, 256f, 257f, 260f, 263f, 275f, 284f, 285f, 286f, 287f, 288f, 289f, 290f, 292f Semispinalis cervicis muscle, 201t, 203f, 257f, 260f, 285f, 288f, 289f, 290f Semispinalis muscles, 205–207, 205f Semispinalis thoracis muscle, 201t, 206f Semitendinosus muscle, 239f, 673f, 679f, 680f, 682f, 686–687 Semitendinosus tendon, 691f, 758f Sentinel lymph nodes, 328b Septal nuclei, 115f Septal vein, 146f, 153, 155f Septum, 71, 71f of testis, 542f Septum pellucidum, 87–91, 91b, 92f, 96f, 103f, 110f, 111f, 115f Serous pericardium, 335 Serratus anterior muscle, 236f, 301f, 392f, 394f, 396, 396f, 397t, 495f, 589f, 597f, 598–599, 598f, 599t, 602f Serratus posterior inferior muscle, 391t, 392f, 393f Serratus posterior superior muscle, 391–392, 391t, 392f, 393f Shaded surface display (SSD), 11, 11f Shingles, 212b Short axis (SA) view, 380–382, 380f, 383f, 384f, 385f Shoulder, 569–605 arterial supply of, 651 articular joint capsule of, 585–586, 585f bony anatomy of, 569–573, 569f, 570f, 571f, 572f bursae of, 586, 586f clavicle, 568f, 569–570, 569f, 570f, 571f, 577f, 578f humerus, 573, 573f, 574f, 575f, 600f, 601f, 602f, 603f, 604f, 606f

778

INDEX

Shoulder (Continued) labrum of, 574f, 575f, 576–577, 576f, 578f, 579f, 581f, 582f, 585f ligaments of, 576–577, 577f, 578f, 579f, 580f, 581f, 582f, 583f, 584f, 585f muscles of, 587–605, 587f, 588f, 589f, 591f, 592f, 593f, 594f, 595f, 596f, 597f, 598f, 599f, 600f, 601f, 602f, 603f, 604f, 605f tendons of, 587–605, 587f, 588f, 589f, 591f, 592f, 593f, 594f, 595f, 596f, 597f, 598f, 599f, 600f, 601f, 602f, 603f, 604f, 605f venous drainage of, 655 Shoulder joint, 578f Sigmoid artery, 486f, 487f Sigmoid colon, 404f, 464–465, 464f, 466f, 467f, 470f, 486f, 527f, 537f Sigmoid sinus, 30f, 31f, 38f, 146, 146f, 149f, 150f, 153f Sigmoid veins, 564f Sinoatrial node, 338f, 339 Sinus tarsi, 692f, 719–721 Sinus tarsi syndrome, 726b Site of hiatus in adductor magnus, 756f Skin, 284f Skull, 13f, 15f, 17f, 26t SMA. see Superior mesenteric artery Small cardiac vein, 351f Small intestine, 402f, 408f, 415f, 449f, 460 Small right cardiac vein, 352f, 379f Small saphenous vein, 758f, 759f SMV. see Superior mesenteric vein Snapping hip syndrome, 672b Soft palate, 251, 251f, 252f, 253f, 254f, 272f, 297f Soleal line, 687–689 Soleus muscle, 691f, 716, 748f Solitary tract nucleus, 169f Somatosensory cortex, 105f Spermatic cord, 495f, 514f, 541f, 544, 545f, 546f, 558f, 559f Sphenoethmoidal recess, 56f, 67f, 70 Sphenofrontal suture, 14f, 15f, 17f, 18f, 44–46, 44f Sphenoid bone, 14f, 15f, 16f, 17f, 20f, 21f, 23–25, 23f, 24f, 25b, 25f, 26f, 26t, 27f, 28f, 29f, 34f, 45f, 48f, 51f, 53f, 54f, 58f, 65f, 75f, 76f, 194f, 287f greater wing of, 150f, 161f Sphenoid sinuses, 17f, 19f, 21f, 23–25, 23f, 24f, 25f, 26f, 28f, 29f, 33f, 34f, 55f, 56f, 58f, 66, 66f, 67f, 70, 70f, 76f, 106f, 113f, 125f, 132f, 133f, 150f, 151f, 152f, 161f, 162f, 171f, 251f, 259f Sphenoparietal suture, 14f, 44–46, 44f Sphenosquamosal suture, 17f, 44–46, 44f, 45f, 48f Sphincter of Oddi, 433–436, 433f, 434f Spinal accessory (posterior triangle) nodes, 280f Spinal artery, 238f, 241, 242f Spinal canal, 181f Spinal cord, 112f, 119f, 120f, 178f, 184f, 186f, 195f, 197f, 210–214, 210f, 213f, 215f, 218f, 221f, 223f, 230f, 231f, 234f cervical enlargement of, 229 descending motor projections to, 120f lumbosacral enlargement of, 229 nerve roots and, 212–214 veins of, 246, 246f Spinal meninges, 210–212, 210f, 213f Spinal muscles, 201–207, 201t, 244f deep layer of, 205–207 intermediate layer of, 204 superficial layer of, 202

Spinal nerve, 178f, 213f, 214, 215f, 221f, 228f, 231f, 244f Spinal nucleus, 169f Spinalis capitis muscle, 201t Spinalis cervicis muscle, 201t, 285f, 300t Spinalis muscle, 204f, 205f Spinalis thoracis muscle, 201t, 206f Spine, 172–249 ligaments of, 194–196, 195f, 198f, 199f, 200f, 201f plexuses of, 228f, 229 brachial, 228f, 229, 232f, 233f, 234f, 235f, 236f cervical, 228f, 229, 230f, 231f lumbar, 228f, 229, 237f, 238f sacral, 228f, 229, 237f, 239f vasculature of, 241–246 Spinoglenoid notch, 581f Spinous process, 174f, 175f, 177f, 178f, 181f, 182f, 183f, 184f, 185f, 188–189f, 189f, 190f, 191f, 194f, 198f, 200f, 203f, 206f, 208f, 213f, 219f, 220f, 226f, 231f, 247f, 587f bifid, 182f, 183f Spiral valves of Heister, 433–436, 434f Spleen, 332f, 390f, 395f, 400f, 401f, 405f, 406f, 407f, 409f, 410f, 412f, 413f, 415f, 416f, 417f, 419f, 420f, 421f, 422f, 424f, 425f, 427f, 428f, 431f, 432f, 437f, 438f, 439f, 441f, 442f, 443, 443f, 445f, 450f, 452f, 457f, 458f, 459f, 463f, 472f, 475f, 477f, 478f, 481f, 482f, 496f, 561f Splenial arteries, 130 Splenic artery, 428f, 429f, 430f, 437f, 439f, 444f, 471f, 472f, 475f, 477f, 478f, 479f, 480–481, 480f, 481f, 482f, 485f, 486f, 487f, 488f, 555f, 561f, 563f Splenic flexure, 461f, 464–465, 467f, 469f Splenic vein, 405f, 424f, 425f, 426f, 427f, 436f, 438f, 439f, 443f, 447f, 463f, 481f, 482f, 483f, 492f, 564f Splenium, of corpus callosum, 99, 102f, 103f, 108f, 111f Splenius capitis muscle, 201t, 202, 202f, 203f, 204f, 234f, 254f, 255f, 256f, 260f, 263f, 275f, 285f, 286f, 287f, 288f, 289f, 290f, 292f, 293f, 299f, 300–301, 300t, 393f, 588f Splenius cervicis muscle, 201t, 202, 202f, 203f, 204f Splenius muscle, 201t, 202, 202f Splenorenal (lienorenal) ligament, 408t Spondylolisthesis, 185b Spondylolysis, 185b Spring ligament, 734–735 Squamous suture, 15f, 17f, 18f, 44–46, 44f, 45f, 46f, 48f SSD. see Shaded surface display Stapes, 31f, 35–37, 35f, 37f, 40f, 42f Stensen’s duct, 271 Sternal angle, 310, 310f, 311f, 324f Sternal end, of clavicle, 569f, 570f Sternoclavicular joint, 304f, 310, 312f, 569–570, 569f, 570f Sternocleidomastoid muscle, 170f, 230f, 233f, 234f, 235f, 236f, 255f, 256f, 257f, 259f, 260f, 263f, 265f, 266f, 267f, 268f, 270f, 271f, 272f, 273f, 274f, 275f, 278f, 279f, 281f, 282f, 284f, 285f, 286f, 287f, 288f, 289f, 290f, 291f, 292f, 293f, 296f, 298, 299f, 300t, 301f, 396f Sternocostal head, 598f Sternohyoid muscle, 260f, 263f, 266f, 267f, 279f, 285f, 290f, 291f, 292f, 293f, 298, 299f, 300t Sternothyroid muscle, 279f, 285f, 292f, 293f, 297f, 298, 299f, 300t

Sternum, 233f, 310, 310f, 311f, 320f, 326f, 327f, 341f, 354f, 367f, 385f, 393f, 598f Stomach, 269f, 400f, 401f, 402f, 403f, 404f, 405f, 406f, 407f, 408f, 409f, 410f, 412f, 413f, 415f, 416f, 417f, 419f, 420f, 421f, 422f, 425f, 428f, 431f, 432f, 434f, 437f, 440f, 441f, 443f, 444f, 445f, 446f, 447f, 449f, 455, 455b, 455f, 456f, 457f, 458f, 459f, 461f, 465f, 477f, 478f, 481f, 482f, 496f Straight sinus, 88f, 146, 146f, 147f, 148f, 150f, 153f, 154f, 155f Strap muscles, 298 Striate arteries, 141f Striate veins, 155f Styloglossus muscle, 294, 294t, 295f, 298f, 299f Stylohyoid ligament, 295f Stylohyoid muscle, 295f, 296f, 298, 299f, 300t Styloid process, 284f, 287f of radius, 609, 628f of temporal bone, 14f, 17f, 28f, 30–32, 30f, 31f, 53f, 63f, 182f of ulna, 607f, 628f Stylomandibular ligament, 63f Stylomastoid foramen, 30–32, 32f, 34f, 41f, 166f Stylopharyngeus muscle, 252f, 272f, 294, 294t, 295f, 296f Subacromial bursa, 585f Subacromial-subdeltoid bursa, 575f, 586, 586f Subarachnoid hemorrhage, 97b Subarachnoid space, 87, 87f, 89f, 91, 95f, 97f, 150f, 161f, 186f, 195f, 210–212, 210f, 211f, 212f, 213f, 214f, 216f, 221f, 223f, 225f, 226f, 227f Subclavian artery, 139f, 230f, 231f, 233f, 236f, 242f, 277f, 281f, 303f, 304f, 305f, 306f, 307f Subclavian vein, 233f, 236f, 277f, 303f, 308f, 368, 588f, 654f, 655, 656f Subclavius muscle, 312f, 396, 397t, 588f, 589f, 598f, 599, 599t Subcostal lumbar vein, 489f Subcutaneous fat, 610f Subcutaneous layer, 397f, 398f Subdeltoid bursa, 585f, 597f Subdural hematoma, 87b Subdural space, 87, 210–212, 213f, 223f Subhepatic space, 408, 411t Sublingual ducts, 271, 271f Sublingual vein, 289f Submandibular duct, 271, 271f, 298f Submandibular glands, 252f, 255f, 256f, 257f, 258f, 259f, 265f, 271, 271f, 274f, 275f, 276f, 280f, 281f, 282f, 289f, 290f, 298f Submandibular lymph node, 275f, 280f, 281f, 288f Submandibular space, 283f Submental nodes, 280f, 282t, 297f Submental vein, 308f Subphrenic space, 408, 411t Subscapular artery, 654f Subscapular bursa, 586, 586f, 597f Subscapular fossa, 570–572 Subscapular nerve, 232f Subscapularis bursa, 576f, 597f Subscapularis muscle, 572f, 576f, 578f, 579f, 580f, 581f, 583f, 585f, 586f, 589f, 592f, 593f, 594f, 590, 595t, 596f, 597f, 602f, 654f

INDEX Subscapularis tendon, 573f, 574f, 575f, 576f, 580f, 583f, 584f, 592f, 594f, 595f Substantia nigra, 120–123, 121f, 122f Subtalar joint, 719–721, 724f, 725f, 727 Subtendinous olecranon bursa, 610f Sulcus, 105f Superficial, 3t Superficial cervical fascia, 285f Superficial circumflex iliac artery, 756f Superficial cortical veins, 153, 153f Superficial fascia of sole of foot, 750f Superficial femoral artery, 528f Superficial inguinal nodes, 566f Superficial middle cerebral vein, 146f, 153f Superficial palmar arch, 651–655, 658f Superficial peroneal nerve, 760f Superficial temporal veins, 308f Superficial transverse perineal muscle, 518f Superior, 3t Superior acetabular labrum, 667f, 670f Superior anastomotic vein, 146f Superior angle, 569f Superior aortic recess, 337f, 337t Superior articular process, 174f, 175f, 176f, 177f, 179f, 180f, 181f, 182f, 188–189f, 189f, 200f, 219f, 238f Superior cerebellar artery, 133f, 135f, 138, 139f, 141f, 142f, 144f, 145f, 145t, 242f Superior cerebellar peduncle, 119f, 127f, 129f Superior colliculi, 112f, 119f, 120–123, 120f, 121f, 126f Superior compartment, of mediastinum, 324, 324t Superior concha, 70 Superior constrictor muscle, 258f, 272f, 286f, 288f, 294, 294t, 295f, 296f Superior costal facet, 175f Superior end plate, 188–189f Superior gemellus muscle, 661f, 666f, 668f, 673f, 674f, 676, 676t Superior glenoid labrum, 575f, 584f, 593f, 595f Superior gluteal artery, 556f, 562f, 752f, 756f Superior gluteal nerve, 237f Superior gluteal vein, 564f Superior ischial ramus, 502f Superior labrum, 582f Superior laryngeal artery, 304f Superior levator palpebrae muscle, 81, 81f, 82f, 84f, 160f Superior lingular segmental bronchus, 322f Superior lobar bronchus, 318f, 322f, 362f Superior lobe, 316f, 318f, 322f Superior margin, 569f Superior margin pubic symphysis, 506f Superior mediastinal nodes, 282t, 297f Superior mediastinum, 324f Superior medullary velum, 93f, 95f Superior mesenteric artery (SMA), 245f, 403f, 419f, 423f, 436f, 438f, 439f, 440f, 441f, 442f, 444f, 453f, 462f, 464f, 468f, 469f, 471f, 472f, 473f, 474f, 475f, 480f, 481f, 482–484, 483f, 484f, 485f, 486f, 487f, 488f, 490f, 555f, 561f, 563f Superior mesenteric nodes, 491f Superior mesenteric vein (SMV), 419f, 423f, 424f, 426f, 427f, 436f, 438f, 439f, 440f, 441f, 453f, 462f, 468f, 469f, 474f, 481f, 483f, 484f, 490f, 564f ileal branches of, 427f jejunal branches of, 427f Superior nasal conchae, 21–22, 22f, 56f, 67f, 157f Superior nasal meatus, 56f, 67, 67f, 68f Superior nuchal line, 202f, 204f

Superior oblique capitis, 207f Superior oblique muscle, 79f, 81, 82f, 83f, 84f, 160f Superior ophthalmic vein, 79, 79f, 80f, 82f, 83f, 150f Superior orbital fissure, 14f, 15f, 23f, 24f, 25f, 49f, 70f, 73, 74f, 75f, 76f Superior pancreaticoduodenal artery, 428f, 480f Superior petrosal sinus, 146f Superior process, 175f Superior pubic ramus, 454f, 498f, 499f, 502f, 503f, 505f, 514f, 524f, 665f, 666f Superior recess, of lesser sac, 407f Superior rectal artery, 486f, 487f, 556f Superior rectal vein, 564f Superior rectus muscle, 81, 81f, 82f, 83f, 159f, 160f Superior sagittal sinus, 88f, 95f, 146, 146f, 147f, 148f, 149f, 153f, 155f Superior semicircular canal, 35f, 38f, 42f, 167f Superior semicircular duct, 37f Superior suprarenal artery, 444f, 473f Superior temporal gyrus, 100–105, 101f, 103f, 105f Superior thoracic aperture, 310 Superior thoracic artery, 650–651f Superior thyroid artery, 263f, 304f Superior thyroid notch, 261f Superior thyroid vein, 303f, 308f Superior ulnar collateral artery, 600f Superior vena cava (SVC), 277f, 303f, 317f, 318f, 319f, 320f, 321f, 325f, 326f, 328f, 330f, 331f, 337f, 338f, 339f, 340f, 348f, 350f, 351f, 352f, 354f, 355f, 356f, 357– 360, 357f, 359f, 360f, 361f, 362f, 365f, 368, 369f, 370f, 371f, 372f, 374f, 379f, 385f, 387f, 388f, 389f, 394f Superior vertebral notch, 175f, 188–189f, 189f Supinator muscle, 605f, 608f, 616t, 617f, 618f, 619f, 620f, 622f, 625f, 626 Supraciliary arch, 14f, 15f Supraclavicular (transverse cervical) nodes, 280f, 282t, 328b Supracolic compartment, 408, 408f, 411t Supraglenoid notch, 589f, 591f Supraglenoid tubercle, 570–572, 571f, 573f Suprahyoid muscle, 274f, 298 Supraoptic nuclei, 111f Supraorbital foramen, 14f, 18, 19f, 74f Supraorbital notch, 18 Suprapatellar bursa, 694f, 709 Suprarenal artery, 473, 474f, 488f, 563f Suprarenal vein, 488f, 491, 563f Suprascapular artery, 581f, 589f, 591f, 592f, 594f, 650–651f Suprascapular nerve, 232f, 581f, 589f, 591f, 592f, 594f, 597f, 657f Suprascapular vessels, 597f Suprasellar cistern, 93f, 95f, 96–97, 97f, 98f, 103f, 106f, 112f, 113f, 116f, 117f, 136f, 144f Supraspinatus muscle, 236f, 571f, 575f, 576f, 578f, 579f, 580f, 582f, 584f, 585f, 587f, 588f, 591f, 593f, 594f, 595f, 590, 595t, 596f, 597f Supraspinatus tendon, 575f, 576f, 577f, 579f, 582f, 585f, 595f, 604f Supraspinous fossa, 570–572, 571f, 572f, 596f Supraspinous ligament, 191f, 194, 195f, 198f, 199f, 200f, 226f Sural artery, 753, 756f

779

Sural nerve, 760f Surgical neck, 573, 574f, 575f, 606f Suspensory ligament, 533f of breast, 397, 397f of ovary, 530f, 532f, 535f Sustentaculum tali, 719–721 Sutures, 44–46, 46b SVC. see Superior vena cava Sylvian fissure. see Lateral (Sylvian) fissure Sympathetic fibers, 150f, 161f Symphysis, mandible, 57f Synovial membrane, 610f of joint capsule, 694f Synovial sheath, 583f, 585f, 586f

T T3, 202f T4, 202f T5, 202f T6, 202f T7, 202f T10, 187f, 188–189f T11, 187f, 188–189f T12, 187f, 188–189f, 215f, 245f, 450f Taenia coli, 464–465, 464f Tail of pancreas, 419f, 421f, 433f, 437f, 439f, 441f, 442f, 447f, 481f of Spence, 397, 397f Talocalcaneal ligament, 734–735 Talocalcaneonavicular joint, 727 Talocrural joint, 692f, 725f, 727 Talus, 692f, 719, 727, 730f, 733f Tarsal canal, 719–721 Tarsal tunnel, 734 Tarsal tunnel syndrome, 734b Tarsals, 719–726 Tarsometatarsal joint, 727 Tectorial membrane, 194, 194f, 195f Tectum, 96–97, 97f, 98f, 119f, 120–123, 120f, 121f, 122f, 125f, 126f, 127f, 128f, 136f, 137f, 154f, 162f Tegmen tympani, 37, 43f Tegmentum, 119, 120f, 121f Temporal bone, 14f, 15f, 16f, 17f, 18f, 20f, 24f, 26t, 27f, 28f, 30–32, 30f, 31f, 32f, 33f, 34f, 35f, 38f, 42f, 44f, 45f, 46f, 49f, 50f, 51f, 53f, 59f, 63f, 166f, 171f, 258f petrous portion of, 93f Temporal horn, of lateral ventricle, 87–91, 90f, 91f, 93f, 94f, 118f, 123f Temporal lobe, 93f, 97f, 100–105, 100f, 101f, 104f, 105f, 106f, 107f, 113f, 114f, 132f, 149f, 165f Temporal process, 49f, 50f, 53, 54f Temporalis muscle, 63, 63f, 64f, 65f, 284f, 286f, 299f, 301f Temporomandibular joint (TMJ), 57, 60–63, 60f, 61f, 62f, 63f, 65f bony anatomy of, 60 Temporomandibular ligament, 61 Tendinous intersections, 495f Tendons, 644–646 Tensor fasciae latae muscle, 208f, 509f, 512f, 661f, 666f, 674f, 675f, 676f, 677f, 679–682, 755f Tensor tympani muscle, 40f Tensor veli palatini muscle, 284f, 295f Tentorial notch, 87, 88f Tentorium cerebelli, 87, 88f, 89f, 94f, 95f, 96f, 125f, 128f, 150f, 161f Teres major muscle, 301f, 578f, 579f, 587f, 589f, 595f, 590, 595t, 596f, 602f, 604f

780

INDEX

Teres minor muscle, 301f, 572f, 577f, 578f, 581f, 583f, 587f, 589f, 592f, 593f, 595f, 590, 595t, 596f, 597f, 602f, 604f Teres minor tendon, 581f, 583f, 584f Terminal bronchiole, 323f Terminology, 2–4, 3t, 4f Tertiary bronchi, 320 Testes, 541f, 542, 542f, 543f Testicular artery, 488f, 541f, 563f Testicular lymph vessels, 331f Testicular vein, 541f, 563f Testis, 522f, 540f, 541f Thalamostriate vein, 146f, 153, 153f, 154f, 155f Thalamus, 92f, 93f, 101f, 102f, 103f, 104f, 105f, 107f, 108f, 109f, 110–112, 111f, 112f, 118f, 119f, 124f, 125f, 128f, 139f, 153f, 157f, 159f, 160f lateral geniculate body of, 159f Thecal sac, 186f, 191f, 194f, 199f, 201f, 210–212, 210f, 211f, 212f, 214f, 217f, 222f, 223f, 224f, 234f, 238f, 239f, 247f, 248f Thenar, 3t Thigh muscles, 683–686 Third lumbar vein, 489f Third metatarsal, 746f Third ventricle, 87–91, 88f, 90f, 91f, 92f, 94f, 101f, 102f, 103f, 104f, 111f, 114f, 115f, 118f, 122f, 124f, 153f, 154f, 218f Thoracic aorta, 316f, 351–352 Thoracic apertures, 310, 310f, 312f, 313f Thoracic cage, 310 Thoracic cavity, 4, 5f, 6t Thoracic duct, 331, 331f, 332f, 491f Thoracic inlet, 310 Thoracic nerves, 210f, 223f Thoracic outlet, 310 Thoracic outlet syndrome (TOS), 310b Thoracic pedicle, 186f Thoracic spinal cord, 200f, 226f Thoracic spine, 316f Thoracic vertebrae, 173f, 175f, 184f, 185, 185f, 186f, 200f, 205f, 210f, 242f, 310, 310f, 312f, 331f, 332f, 341f, 354f, 355f, 389f, 395f, 570f Thoracoacromial artery, 650–651f Thoracodorsal nerve, 232f, 657f Thoracolumbar fascia, 208f Thorax, 309–398, 309f muscles of, 391t, 392f, 396f Thymic vein, 379f Thymus, 324f Thymus gland, 325, 325b, 325f, 326f Thyrocervical trunk, 303f Thyroepiglottic ligament, 261–264, 261f, 265f Thyrohyoid ligament, 261f Thyrohyoid membrane, 261f, 295f Thyrohyoid muscle, 258f, 260f, 263f, 266f, 267f, 285f, 290f, 291f, 298, 299f, 300t Thyroid cartilage, 4f, 251f, 253f, 257f, 258f, 259f, 260f, 261–264, 261f, 262f, 263f, 266f, 267f, 268f, 274f, 277f, 278f, 285f, 290f, 291f, 292f, 295f, 297f, 328f Thyroid gland, 234f, 235f, 252f, 253f, 258f, 259f, 261f, 262f, 267f, 270f, 274f, 277, 277f, 278f, 279f, 285f, 292f, 293f, 297f, 325f Thyroid nodules, 277b Tibia, 687–689, 690f, 691f, 692f, 694f, 696f, 713f, 714f Tibial arteries, 753, 757f Tibial collateral ligament, 694f Tibial nerve, 237f, 691f, 758f, 760f

Tibial plateaus, 687–689, 690f Tibial shaft, 692f Tibial tuberosity, 687–689, 687f, 690f, 691f, 692f Tibialis anterior muscle, 690f, 691f, 696f, 711 Tibialis anterior tendon, 692f, 745f, 747–748 Tibialis posterior muscle, 716–717 Tibialis posterior tendon, 692f, 748 Tibiocalcaneal ligament, 734–735 Tibiofibular articulation, 691f Tic douloureux, 165b TMJ. see Temporomandibular joint Tongue, 64f, 251f, 252f, 253f, 258f, 262f, 268f, 271f, 274f, 275f, 294, 294t, 295f, 297f, 298f muscles of, 170f Torcular herophili, 146 TOS. see Thoracic outlet syndrome Trachea, 231f, 234f, 235f, 251f, 252f, 253f, 257f, 258f, 259f, 261f, 262f, 269, 269f, 270f, 278f, 279f, 285f, 292f, 293f, 303f, 314f, 315f, 322f, 324f, 327, 327f, 328f, 330f, 354f, 356f, 362f, 364f, 367f, 392f Tracheal cartilage, 252f, 261f, 277f, 279f Tracheostomy, 269b Tragus, 31f Transition zone, 549 Transtentorial herniation, 87b Transversalis fascia, 493f Transverse abdominis muscle, 493f, 494f Transverse acetabular ligament, 665, 665f, 666f, 667f, 668f, 670f, 671f Transverse colon, 402f, 408f, 415f, 435f, 436f, 460f, 461f, 462f, 464–465, 464f, 465f, 466f, 467f, 468f, 469f, 485f, 486f Transverse fissure, 415f Transverse foramen, 179f, 182f, 183f Transverse humeral ligament, 576–577, 577f, 581f, 583f, 592f Transverse ligament, 194f, 195f, 196f, 197f, 225f, 695, 695f, 698f Transverse mesocolon, 485f, 486f Transverse process, 174f, 175f, 179f, 180f, 181f, 182f, 183f, 185f, 187f, 188–189f, 189f, 190f, 198f, 207f, 222f, 230f of atlas, 295f Transverse rectal fold, 527 Transverse reticular ligament, 642f Transverse sinus, 146, 146f, 149f, 150f, 153f, 335, 337f, 337t Transversospinal muscles, 205–207, 207f, 208f, 209f, 393f, 494f Transversus abdominis muscle, 204f, 208f, 492–494, 495f, 496f, 496t Transversus thoracis muscle, 391f Trapezium bone, 626, 627f, 628f, 629f, 630f, 634f, 640f, 649f Trapezius muscle, 170f, 202f, 203f, 205f, 234f, 236f, 255f, 256f, 260f, 263f, 267f, 270f, 275f, 284f, 285f, 288f, 289f, 290f, 291f, 292f, 293f, 299f, 300–301, 300t, 301f, 393f, 396f, 571f, 576f, 579f, 582f, 587, 587f, 588f, 589f, 590t, 593f, 594f, 597f Trapezoid bone, 626, 627f, 628f, 629f, 630f, 631f, 634f, 640f, 649f Triangular fibrocartilage complex, 631f, 633, 634f, 640f Triangular ligaments, 406f, 408t Triceps brachii muscle, 301f, 600f, 601f, 602f, 603f, 604f, 605, 605f, 605t, 608f, 609f, 610f, 613f, 623f Triceps brachii tendon, 572f, 597f, 602f, 623f Triceps muscle, 578f, 595f

Tricuspid valve, 333f, 336f, 338f, 341f, 343f, 348f, 349f Trigeminal ganglion, 163–165, 163f Trigeminal nerve, 119f, 124f, 150f, 152f, 156f, 156t, 161f, 162f, 163–165, 163f, 164f, 167f, 218f Trigeminal neuralgia, 165b Trigone, 87–91, 90f, 517f, 520–521 Triquetral bone, 626, 627f, 628f, 629f, 630f, 631f, 632f, 633f, 634f, 639f Triquetrohamate ligament, 635f Trochanteric bursae, 672 Trochlea, 84f, 574f, 606f, 607f, 609f, 610f, 719 Trochlear nerve, 119f, 150f, 152f, 156f, 156t, 160f, 161f, 162f, 163 Trochlear notch, 607f, 609, 609f True pelvis, 506f, 507f True vocal cords, 261f, 263f, 264, 266f, 268f True vocal folds, 251f Tuberculum sellae, 23–25, 23f Tunica albuginea, 542, 542f Tympanic annulus, 42f Tympanic cavity, 32f, 35–37, 35f Tympanic membrane, 31f, 35–37, 35f, 41f, 42f, 43f, 166f

U Ulna, 232f, 599f, 605f, 607f, 609, 609f, 610, 610f, 611f, 640f, 649f, 652f, 654f, 655f Ulnar artery, 619f, 620f, 621f, 645f, 650–651f, 651, 652f, 653f, 654f, 655f, 658f Ulnar collateral ligament, 611f, 612, 612f, 622f, 635–636 Ulnar nerve, 232f, 600f, 601f, 602f, 603f, 611f, 614f, 620f, 621f, 657f, 658f Ulnar notch, 607f, 609 Ulnar styloid process, 607f Ulnar tuberosity, 599f, 607f, 609 Ulnar vein, 654f, 655f Ulnohumeral articulation, 606, 606f Ulnolunate ligament, 635f Ulnotriquetral ligament, 635f Umbilical artery, 555f, 556f Umbilical vein, 564f Umbilicus, 523f Uncinate process, 21–22, 22f, 51f, 72–73, 72f, 73f, 180f, 181f, 182f of pancreas, 439, 439f, 440f, 442f, 481f Upper extremity, 568–658, 568f Upper internal jugular vein lymph node, 288f Upper lobe, 322f Upper pole, of left kidney, 448f, 449f Upper segmental artery, 474f, 475f Upper subscapular nerve, 232f, 657f Ureter, 448f, 449f, 451, 451f, 473f, 476f, 484f, 488f, 517f, 522f, 525f, 530f, 532f, 533f, 540f Ureteral openings, 517f Urethra, 513f, 515f, 517f, 520f, 521, 521f, 526f, 528f, 529f, 535f, 539f female, 521 male, 521 Urinary bladder, 402f, 415f, 516f, 517f, 519f, 520–521, 520f, 521f, 522f, 523f, 524f, 525f, 527f, 528f, 529f, 531f, 532f, 533f, 534f, 535f, 536f, 537f, 538f, 539f, 540f, 541f, 560f, 564f neck of, 520–521, 520f Urinary system, 448–451, 448f, 449f, 450f, 451f, 452f, 453f, 454f Urogenital triangle, 518f Uterine artery, 556f

INDEX Uterine cavity, 516f, 529f, 530f, 531f, 535f, 536f Uterine tube, 529f, 530f, 532f, 533f, 535 Uterine vein, 564f Uterine venous plexus, 564f Uterosacral ligament, 532, 532f, 533f, 539f Uterus, 402f, 404f, 520f, 523f, 525f, 529–530, 529f, 530f, 532f, 533f, 534f, 536f, 537f, 539f, 564f, 566f suspensory ligaments of, 531f, 532, 533f Utricle, 37f Utricular duct, 37f Uvula, 251, 251f, 252f, 253f, 254f, 262f, 288f, 297f

V Vagina, 513f, 515f, 516f, 519f, 520f, 521f, 528f, 529f, 530f, 531f, 535, 537f, 538f, 539f, 564f Vaginal artery, 556f Vaginal venous plexus, 564f Vagus nerve, 119f, 156f, 156t, 168–170, 168f, 169f, 170b, 170f, 231f, 284f, 285f activation of, 170b Valleculae, 251–256, 252f, 253f, 256f, 257f, 262f, 265f, 289f Vas deferens, 522f, 540f, 541f, 544, 544f Vasculature, of pelvis, 555–565 arteries, 555 venous drainage, 563–565 Vastus intermedius muscle, 241f, 678f, 679f, 680f, 682f Vastus lateralis muscle, 675f, 678f, 679f, 680f, 681f, 682f, 755f, 758f Vastus medialis muscle, 678f, 679f, 681f, 682f, 697f Vein of Galen, 146, 146f, 147f, 148f, 150f, 153f, 154f, 155f, 159f Vein of Rosenthal, 153 Venous plexus, 563–565, 564f Ventral, 3t Ventral cavity, 4, 5f, 6t Ventral horn, 213f, 214, 223f Ventral ramus, 213f, 221f, 222f, 228f, 229 Ventral root, 213f, 214, 216f, 218f, 219f, 221f, 226f, 227f, 228f Ventricle, 87–91, 90f, 91f, 338 fourth, 87–91, 90f, 91f, 93f, 94f, 95f, 96f, 98f, 99f, 102f, 111f, 112f, 120f, 123f, 124f, 125f, 126f, 127f, 128f, 129f, 162f, 163f, 165f, 167f, 169f lateral, 87–91, 88f, 93f, 96f, 101f, 106f, 111f, 125f, 148f, 154f third, 87–91, 88f, 90f, 91f, 92f, 94f, 101f, 102f, 103f, 104f, 111f, 114f, 122f, 124f, 153f, 154f Ventricular system, of brain. see also Ventricle, 95, 87–97, 90f, 93f Ventromedial nucleus, 111f Vermiform appendix, 460f, 464–465, 464f, 466f

Vermis, 97f, 114f, 116f, 117f, 125f, 127, 127f, 128f, 129f, 162f Vertebra prominens, 204f Vertebrae, 273f, 447f cervical, 179–180, 180f, 181f, 182f, 184f, 196f, 199f, 210f, 213f, 242f, 248f lumbar, 173f, 174f, 175f, 185, 187f, 189f, 190f, 191f, 199f, 200f, 201f, 206f, 209f, 210f, 219f, 220f, 222f, 238f, 242f, 245f, 248f, 249f pedicle of, 174f, 175f, 182f, 185f, 188–189f, 189f, 190f, 198f, 215f, 219f, 221f, 238f superior view of, 174f thoracic, 173f, 175f, 184f, 185, 185f, 186f, 200f, 205f, 210f, 242f, 310, 310f, 312f Vertebral arch, 174f Vertebral artery, 131f, 134f, 135f, 138, 139f, 140f, 141f, 142f, 143f, 144f, 145f, 160f, 167f, 169f, 170f, 180f, 233f, 242f, 243f, 246f, 248f, 257f, 265f, 266f, 273f, 279f, 285f, 286f, 287f, 288f, 289f, 290f, 291f, 292f, 293f, 295f, 302, 302t, 303f, 304f, 305f, 306f, 307f branches of, 145t segments of, 138t Vertebral body, 174f, 175f, 180f, 182f, 183f, 185f, 188–189f, 189f, 192f, 193f, 198f, 200f, 213f, 219f, 221f, 226f, 234f, 247f, 249f, 270f, 385f Vertebral column, 173–191 veins of, 246, 246f Vertebral end plates, 175f, 178f, 198f Vertebral foramen, 174f, 182f, 188–189f Vertebral prominens, 4f, 183f, 184f Vertebral vein, 246f, 248f, 285f, 302t, 308 Vertebral venous plexuses, 246b Vertebrobasilar arterial system, 139f Vertex, 15f, 17f, 18, 18f, 44f Vertical body, 203f Vertical long axis (VLA) view, 380–382, 380f, 381f Verumontanum, 549 Vesical fascia, 539f Vesical vein, 564f Vesical venous plexus, 564f Vesicouterine pouch, 529f, 533f, 534f, 539, 539f Vestibular aqueduct, 37f, 38–44 Vestibular cochlear nerve, 35f Vestibular complex, 35f, 166f Vestibular folds, 251f, 261f, 262f, 264, 297f Vestibular ganglion, 31f Vestibular nerve, 31f Vestibule, 33f, 35f, 36f, 37f, 38–44, 39f, 42f, 167f, 168f Vestibulocochlear nerve, 119f, 156f, 156t, 166f, 167f, 168 Viscera, pelvic, 520–552 bladder, 520–521 rectum, 527 reproductive organs female, 529–539 male, 540–552

781

Visceral nodes, 282t, 292f, 293f Visceral pericardium, 335f Visceral peritoneum, 400f Visceral pleura, 314, 314f Visceral space, 283f, 285f, 291f, 292f, 293t Visual cortex, 159f Visual system, damage to, 160b Vitreous humor, 77, 77f, 78f Vocal cords, 261f, 263f, 264, 266f, 268f, 291f Vocal folds, 251f Vocalis muscle, 268f Volar, 3t Volume rendering (VR), 11, 12f Vomer, 15f, 17f, 22f, 49f, 52f, 56, 85f Voxel, 7f VR. see Volume rendering

W Wernicke’s area, 100–105, 105f Wharton’s duct, 271, 276f White matter, 101f, 213f, 214, 223f organization of, 99–100 White pulp, of spleen, 443, 444f Window width, 7 Windowing, 7, 8f Wrist. see also Hand, 639 arteries of, 650–651f, 651–655 bony anatomy of, 626, 627f, 628f, 629f, 630f, 631f extensor tendons of, 639f fascia of, 635–641 joints of, 633, 633f ligaments of, 635–641, 635f, 636f venous drainage of, 656, 656f

X Xiphoid process, 310, 310f, 311f

Z Zona orbicularis, 665f, 667f, 668f, 669f, 670f, 671f Zygapophyseal joint, 176f, 177f, 188–189f, 200f, 230f Zygoma, 15f, 21f, 24f, 28f, 31f, 49f, 50f, 51f, 52f, 53f, 54f, 55f, 57f, 58f, 59f, 67f, 69f, 72f, 74f, 75f, 76f, 171f Zygomatic arch, 15f, 26f, 27f, 28f, 30–32, 31f, 33f, 50f, 51f, 53, 53f, 54f, 57f, 58f, 70f Zygomatic bones, 53 Zygomatic process, 28f, 30–32, 30f, 31f, 49f, 50–53, 50f, 51f, 52f, 54f, 59f, 63f Zygomaticus muscle, 301f

This page intentionally left blank