Trunk / Thorax Muscles

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Cheat Sheet (English Terminology)

Trunk Wall: Muscle Charts

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Superficial (Extrinsic) muscles of back

Suboccipital muscles

Origin

Insertion

Rectus capitis

Posterior tubercle of

Medial part of inferior

Atlantooccipital joint: Head

posterior minor

atlas

nuchal line

extension

Lateral part of inferior

Bilateral contraction -

nuchal line

Atlantooccipital joint: Head extension

Transverse process of atlas

Unilateral contraction Atlantoaxial joint: Head

Rectus capitis posterior major

Obliquus capitis inferior

Obliquus capitis superior

Spinous process of axis

Spinous process of axis

Transverse process of atlas

Occipital bone (between superior and inferior nuchal lines)

Innervation

Posterior ramus of spinal nerve C1 (suboccipital nerve)

Function

rotation (ipsilateral) Bilateral contraction Atlantooccipital joint: Head extension Unilateral contraction Atlantoaxial joint: Head rotation (contralateral), Head lateral flexion (ipsilateral)

Superficial layer

Origin

Descending part: Medial third of superior nuchal line, External occipital protuberance, Spinous processes of cervical vertebrae/Nuchal ligament Trapezius

Transverse part: Broad aponeurosis at spinous processes of vertebrae T1-T4 (or C7-T3)

Insertion

Descending part: Lateral third of clavicle Transverse part: Medial aspect of acromion, Superior crest of spine of scapula Ascending part: Medial end of spine of scapula

Innervation

Descending part: Scapulothoracic joint: Draws scapula superomedially; Atlantooccipital joint/ upper cervical vertebrae: Motor: Accessory nerve (CN XI) Sensory: Anterior rami of spinal nerves C3-C4 (via cervical plexus)

Ascending part: Spinous processes of vertebrae T5-T12 (or T2-T12)

Levator scapulae

Transverse processes of vertebrae C1-C4

Rhomboid major

Spinous process of vertebrae T2-T5

Rhomboid minor

Nuchal ligament, Spinous processes of vertebrae C7-T1

Function

Extension of head and neck, Lateral flexion of head and neck (ipsilateral); Altantoaxial joint: Rotation of head (contralateral) Transverse part: Scapulothoracic joint: Draws scapula medially Ascending part: Scapulothoracic joint: Draws scapula inferomedially (All parts support scapula)

Anterior rami of spinal nerves C3-C4, Dorsal scapular nerve (C5)

Scapulothoracic joint: Draws scapula superomedially, Rotates glenoid cavity inferiorly; Cervical joints: Lateral flexion of neck (ipsilateral)

Dorsal scapular nerve (C5)

Scapulothoracic joint: Draws scapula superomedially, Rotates glenoid cavity inferiorly; Supports position of scapula

Intertubercular sulcus of humerus

Thoracodorsal nerve (C6C8)

Shoulder joint: Arm internal rotation, Arm adduction, Arm extension; Assists in respiration

Insertion

Innervation

Function

Superior borders of ribs 2-5

2nd-5th Intercostal nerves

Elevates ribs

Medial border of scapula (from superior angle to root of spine of scapula)

Medial border of scapula (from inferior angle to root of spine of scapula) Root (medial end) of spine of scapula

Vertebral part: Spinous

Latissimus dorsi

processes of vertebrae T7-T12, Thoracolumbar fascia Iliac part: Posterior third of crest of ilium Costal part: Ribs 9-12 Scapular part: Inferior angle of scapula

Intermediate layer

Origin

Serratus

Nuchal ligament, spinous

posterior superior

processes of vertebrae C7-T3

Serratus posterior inferior

Anterior rami of spinal Spinous processes of vertebrae T11-L2

Inferior borders of ribs 9-12

nerves T9-T12 (a.k.a. 9th-11th Intercostal nerves + subcostal nerve)

Depresses ribs/ Draws ribs inferoposteriorly

Deep (Intrinsic) muscles of back

Superficial layer

Splenius capitis

Origin

Insertion

Innervation

Spinous processes of vertebrae C7-T3, nuchal ligament

Lateral superior nuchal line of occipital bone, Mastoid process of temporal bone

Lateral branches of posterior rami of spinal nerves C2-C3

Transverse processes of vertebrae C1-C3

Lateral branches of posterior rami of lower cervical spinal nerves

Function Bilateral contraction Extends head/neck Unilateral contraction Lateral flexion and rotation of head (ipsilateral) Bilateral contraction -

Splenius cervicis

Spinous processes of vertebrae T3-T6

Extends neck Unilateral contraction Lateral flexion and rotation of neck (ipsilateral)

Intermediate layer

Origin

Insertion

Iliocostalis cervicis: Angle of ribs 3-6

Iliocostalis cervicis: Transverse processes of vertebrae C4-C6

Iliocostalis thoracis: Angle of ribs 7-12

Iliocostalis thoracis: Angles of ribs 1-6,

Erector spinae group Spinalis

Function

Bilateral contraction Extension of spine

Transverse process of vertebra C7

Iliocostalis

Longissimus

Innervation

Unilateral contraction Lateral flexion of spine (ipsilateral)

Iliocostalis lumborum: Lateral crest of sacrum, Medial end of iliac crest, Thoracolumbar fascia

Iliocostalis lumborum: Angle of ribs 5-12, Transverse processes of vertebrae L1-L4 (+ Adjacent thoracolumbar fascia)

Longissimus capitis: Transverse processes of vertebrae C4-T5

Longissimus capitis: Mastoid process of temporal bone

Longissimus cervicis: Transverse processes of

Longissimus cervicis: Transverse processes of

vertebrae T1-T5

vertebrae C2-C6

Longissimus thoracis: Lumbar part: Lumbar intermuscular aponeurosis, anteromedial aspect of ilium, Posterior sacroiliac ligament

Longissimus thoracis: Lumbar part: Accessory and transverse processes of vertebrae L1-L5

Thoracic part:  Spinous and transverse processes of vertebrae L1-L5, Median sacral crest, Posterior surface of sacrum , Posterior iliac crest

Thoracic part: Transverse process of vertebrae T1-T12, Angles of ribs 7-12

Spinalis cervicis: Spinous

Spinalis cervicis: Spinous

Bilateral contraction -

processes of vertebrae C7-T1, Nuchal ligament

processes of vertebrae C2-C4

Extension of cervical and thoracic spine

Spinalis thoracis: Spinous processes of vertebrae T11-L2

Spinalis thoracis: Spinous processes of vertebrae

Unilateral contraction Lateral flexion of

T2-T8

cervical and thoracic spine (ipsilateral)

Lateral branches of posterior rami of spinal nerves

Entire muscle: Bilateral contraction Extension of spine Unilateral contraction Lateral flexion of spine (ipsilateral) Longissimus capitis only: Bilateral contraction Extension of head and neck Unilateral contraction Lateral flexion and rotation of head (ipsilateral)

Deep layer

Origin

Semispinalis capitis: Articular processes of vertebrae C4-C7, Transverse processes of vertebrae T1-T6

Transversospinales group

Semispinalis

Insertion Semispinalis capitis: Between superior and inferior nuchal lines of occipital bone Semispinalis cervicis:

Semispinalis cervicis: Transverse processes of vertebrae T1-T6

Spinous processes of vertebrae C2-C5

Semispinalis thoracis: Transverse processes of vertebrae T6-T10

Semispinalis thoracis: Spinous processes of vertebrae C6-T4

Innervation

Semispinalis capitis: Descending branches of greater occipital nerve (C2) and spinal nerve C3 Semispinalis cervicis/ thoracis: Medial branches of posterior rami of spinal nerves

Function Bilateral contraction Extension of head, cervical and thoracic spine Unilateral contraction Lateral flexion of head, cervical and thoracic spine (ipsilateral), Rotation of head, cervical and thoracic spine (contralateral)

Multifidus cervicis: Superior articular processes of vertebrae C4-C7 Multifidus thoracis: Transverse process of thoracic vertebrae Multifidus Multifidus lumborum: Mammillary processes of lumbar vertebrae, Posterior aspect of sacrum, Posterior superior iliac spine (PSIS) of ilium, Posterior sacroiliac ligament

Bilateral contraction Extension of spine

Lateral aspect and tips of spinous processes of vertebrae 2-5 levels above origin

Unilateral contraction Lateral flexion of spine (ipsilateral), Rotation of spine (contralateral) Medial branches of posterior rami of spinal nerves

Rotatores breves:

Rotatores breves and longi

Rotatores breves: Transverse processes of vertebrae T2-T12

Laminae/Spinous process of vertebra (1 level above origin)

Bilateral contraction Extension of thoracic spine

Rotatores longi: Transverse

Rotatores longi:

Unilateral contraction -

processes of thoracic vertebrae

Laminae/Spinous process of vertebra (2 levels above origin)

Rotation of thoracic spine (contralateral)

Deepest layer

Interspinales

Intertransversarii

Origin

Insertion

Interspinales cervicis: Superior aspect of spinous processes of vertebrae C2-C7

Interspinales cervicis: Inferior aspect of spinous processes of vertebrae C1-C6

Interspinales thoracis:

Interspinales thoracis: Inferior aspect of spinous processes of vertebrae T1, T10 & T11

Superior aspect of spinous process of vertebrae T2, T11 & T12 (variable) Interspinales lumborum: Superior aspects of spinous processes of vertebrae L2-L5

Interspinales lumborum: Inferior aspects of spinous processes of vertebrae L1-L4

Anterior/posterior cervical intertransversarii: Superior border of transverse processes of vertebrae C2-T1

Anterior/posterior cervical intertransversarii: Inferior border of transverse process of superior adjacent cervical vertebra

Medial lumbar intertransversarii: Accessory processes of vertebrae L1-L4 Lateral lumbar intertransversarii: Transverse and accessory processes of vertebrae L1-L4

Levatores costarum

Transverse process of vertebrae C7-T11

Medial lumbar intertransversarii: Mammillary process of succeeding vertebra Lateral lumbar intertransversarii: Transverse process of succeeding vertebra Superior border/external surface of rib (one level below origin)

Innervation

Function

Posterior rami of spinal nerves

Extension of cervical and lumbar spine

Anterior cervical intertransversarii: Anterior and posterior rami of cervical spinal nerves

Lumbar intertransversarii: Anterior rami of lumbar spinal nerves

Posterior rami of spinal nerves T1-T12

Assists in lateral flexion of the spine; Stabilises spine

Elevation of ribs; Rotation of thoracic spine

Anterolateral muscles of trunk

Muscles of thoracic cage

Origin

Insertion

Innervation

Function

Clavicular head: anterior surface of clavicle (medial half)

Pectoralis major

Sternocostal head: Anterior surface of sternum, Costal cartilages of ribs 1-6

Crest of greater tubercle

Lateral and medial

of humerus (all heads)

pectoral nerves (C5-T1)

Abdominal (Rectus) head: Anterior layer of rectus sheath

Pectoralis minor

Anterior surface, Costal cartilages of ribs 3-5

Medial border and coracoid process of scapula

Shoulder joint: Arm adduction, Arm internal rotation, Arm flexion (clavicular head), arm extension (sternocostal head); Scapulothoracic joint: Draws scapula anteroinferiorly

Scapulothoracic joint: Medial pectoral nerve (C8-T1)

Draws scapula anteroinferiorly, stabilizes scapula on thoracic wall

Muscles of thoracic cage

Origin

Superior part: Ribs 1-2, Intercostal fascia Serratus anterior

Middle part: Ribs-3-6 Inferior part: Ribs 7-8/9/10 (+ external oblique muscle)

Subclavius

External intercostals

Costal cartilage, Sternal end of rib 1

Insertion

Innervation

Function

Long thoracic nerve (C5-C7)

Scapulothoracic joint: Draws scapula anterolaterally, Suspends scapula on thoracic wall,

Superior part: Anterior and posterior surface of superior angle of scapula Middle part: Anterior surface of entire medial border of scapula

Rotates scapula (draws inferiorly angle laterally)

Inferior part: Anterior and posterior surface of inferior angle of scapula Anteroinferior surface of middle third of clavicle

Nerve to subclavius (C5-C6)

Elevate ribs during forced inspiration; Supports intercostal spaces and thoracic cage

Inferior border of ribs Superior border of immediate rib below

Internal intercostals Costal groove of ribs Innermost intercostals

Intercostal nerves

Subcostal

Internal surface of ribs

Internal surface of rib

muscles

(near angle of rib)

(2-3 levels below origin)

Transversus thoracis

Inferoposterior surface of body of sternum and xiphoid process

Sternoclavicular joint: Anchors and depresses clavicle

Internal surface of costal cartilages of ribs 2-6

Depresses ribs during forced expiration; Supports intercostal spaces and thoracic cage

Depresses costal cartilages

Sternal part: Posterior aspect of xiphoid process Costal part: Internal surfaces of lower costal cartilages and ribs 7-12 Respiratory diaphragm

Lumbar part: Medial and lateral arcuate ligaments (lumbocostal arches), Bodies of vertebrae L1-L3 (+ intervertebral discs), Anterior longitudinal ligament

Phrenic nerves (C3-C5) Central tendon of diaphragm

(Sensory innervation of peripheries via 6th-11th intercostal nerves)

Depresses costal cartilages, Primary muscle of breathing (inspiration)

Muscles of abdominal wall

External abdominal oblique

Internal abdominal oblique

Cremaster

Origin

External surfaces of ribs 5-12

Anterior two-thirds of iliac crest, Iliopectineal arch, Thoracolumbar fascia

Lateral part: Lower edge of internal abdominal oblique and transversus abdominis muscles, Middle of inguinal ligament

Insertion

Linea alba, Pubic tubercle, Anterior half of iliac crest

Inferior borders of ribs 10-12, Linea alba, Pubic crest, Pecten pubis (via conjoint tendon)

Innervation

Intercostal nerves (T7T11), Subcostal nerve (T12), Iliohypogastric nerve (L1)

Intercostal nerves (T7T11), Subcostal nerve (T12), Iliohypogastric nerve (L1), Ilioinguinal nerve (L1)

Tunica vaginalis of testis

Genital branch of genitofemoral nerve (L1, L2)

Linea alba, Aponeurosis of internal abdominal oblique muscle; Pubic crest, Pectinal line of pubis

Intercostal nerves (T7T11), Subcostal nerve (T12), Iliohypogastric nerve (L1), Ilioinguinal nerve (L1)

Xiphoid process, Costal cartilages of ribs 5-7

Intercostal nerves (T7-T11), Subcostal nerve (T12)

Linea alba

Subcostal nerve (T12)

Function Bilateral contraction Trunk flexion, Compresses abdominal viscera, Expiration Unilateral contraction Trunk lateral flexion (ipsilateral), Trunk rotation (contralateral) Bilateral contraction Trunk flexion, Compresses abdominal viscera, Expiration Unilateral contraction Trunk lateral flexion (ipsilateral), Trunk rotation (ipsilateral)

Retraction of testis

Medial part: Pubic tubercle, Lateral part of pubic crest Internal surfaces of Transversus abdominis

Rectus abdominis

Pyramidalis

costal cartilages of ribs 7-12, Thoracolumbar fascia, Anterior two thirds of iliac crest, Iliopectineal arch Pubic symphysis, Pubic crest Pubic crest, Pubic symphysis

Bilateral contraction Compresses abdominal viscera, Expiration Unilateral contraction Trunk rotation (ipsilateral) Trunk flexion, Compresses abdominal viscera, Expiration Tenses linea alba Bilateral contraction -

Quadratus lumborum

Iliac crest, Iliolumbar ligament

Inferior border of rib 12, Transverse processes of vertebrae L1-L4

Subcostal nerve (T12), Anterior rami of spinal nerves L1-L4

Fixes Ribs 12 during inspiration, Trunk extension Unilateral contraction Lateral flexion of trunk (ipsilateral)

Muscles of pelvic floor

Pelvic diaphragm

Levator ani

Puborectalis

Pubococcygeus

Origin

Insertion

Posterior surface of

None (forms 'puborectal

bodies of pubic bones

sling' posterior to rectum)

Posterior surface of bodies of pubic bones (lateral to puborectalis) Tendinous arch of interal

Iliococcygeus

Coccygeus

obturator fascia, Ischial spine Ischial spine Ischiopubic ramus,

Obturator internus

Posterior surface of obturator membrane

Innervation

Nerve to levator ani (S4)

Anococcygeal ligament, Coccyx, Perineal body and musculature of prostate/ vagina

(Pubococcygeus also receives branches via

Piriformis

Supports pelvic viscera, Increases intraabdominal pressure, Assists with fecal and urinary continence

Anococcygeal ligament, Coccyx

inferior rectal/ perineal branches of pudendal nerve (S2-S4))

Inferior end of sacrum,

Anterior rami of spinal

Supports pelvic viscera,

Coccyx

nerves S4 & S5

Flexes coccyx

Greater trochanter of femur

Nerve to obturator internus (L5-S2)

Greater trochanter of femur

Nerve to piriformis (S1, S2)

Anterior surface of S2-S4 segments of sacrum, Superior margin of greater sciatic notch, Sacrotuberous ligament

Function

Hip joint: Thigh external rotation, Thigh abduction (from flexed hip); Stabilises head of femur in acetabulum

Perineal muscles

Origin

Insertion

Innervation

Function

External anal sphincter

Skin/fascia surrounding anal canal/anus

Perineal body, Anococcygeal ligament (encircles anus)

Inferior anal/rectal branch of pudendal nerve (S2-S4)

Constricts anal canal, Supports pelvic floor

Bulbospongiosus

Male: Perineal body, Median penile raphe Female: Perineal body

Male: Compresses bulb of penis during urination/ ejaculation, Assists in erection of penis, Supports perineal body

Male: Perineal membrane, Dorsal aspect of corpus spongiosum and corpora cavernosa, Fascia of bulb of penis

Female: Assists in erection of clitoris/bulb of vestibule, Supports perineal body

Female: Pubic arch, Fascia of corpora cavernosa and clitoris

Pushes blood from root Ischiocavernosus

Deep transverse perineal muscle

Ischial tuberosity & ramus

Inferior pubic rami, Ischial rami

Crus of clitrois or penis

Walls of vagina (female)/ Prostate (male) Perineal body

Superficial transverse perineal muscle

Ischial tuberosities

Deep branch of perineal nerve (of pudendal nerve) (S2-S4)

of clitoris/penis to body i.e. maintains erection of penis/clitoris

Strengthens pelvic floor/ perineal body to support abdominopelvic viscera

Perineal body

Male: encircles membranous urethra, extends to anterior

External urethral sphincter

aspect prostatic urethra/neck of urinary bladder and to ischial rami (compressor urethrae) Female: encircles urethra/neck of bladder, extends to ischial rami (compressor urethrae), encircles urethra/ vagina (urethrovaginal sphincter)

Maintains urinary continence (compresses urethra) (Female: Constricts vaginal canal)

Complete your muscle charts collection Congratulations - you’ve conquered the origins, insertions, innervations and functions of the muscles of the trunk! But there’s still a lot of muscles to learn, so don’t stop here. The next step is to master the lower limb, upper limb and head & neck muscles. Luckily, we have muscle charts on every region of the body. Click below to learn more.

Cheat Sheet (English Terminology)

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