OIAN Thorax, Neck, Back

external intercostal origin

inferior border of rib above

external intercostal insertion

superior border of rib below, fibers run obliquely “down and in”

external intercostal action

inspiration (decreases intrapleural pressure), moves rib superiorly

external intercostal innervation

innervated by intercostal nerve of given level, originating from anterior rami of thoracic spinal nerves T1-T11

internal intercostal origin

costal groove of ribs

internal intercostal insertion

superior border of immediate rib below

internal intercostal action

expiration, move ribs inferiorly, support intercostal spaces and thoracic cage

internal intercostal innervation

intercostal nerves of given level

internal intercostal blood supply

anterior intercostal, posterior intercostal, internal thoracic and musculophrenic arteries, costocervical trunk

external intercostal blood supply

anterior and posterior intercostal arteries

transversus thoracis origin

inferior part of body of sternum and xiphoid (deep surface)

transversus thoracis insertion

inferior margins and deep surface of costal cartilages of ribs 2 to 6

transversus thoracis action

depress ribs

transversus thoracis innervation

intercostal nerves at the levels of the muscle

transversus thoracis blood supply

sternal branches and anterior intercostal branches of internal thoracic artery

levatores costorum origin

transverse process C7 to T11

levatores costorum insertion

insert rib below origin (brevis) or two below (longus)

levatores costorum action

elevate ribs

levatores costorum innervation

posterior rami at the levels of the muscle

levatores costorum blood supply

dorsal branches of the posterior intercostal arteries

serratus posterior superior origin

spinous process C7-T3

serratus posterior superior insertion

angle of rib 2-4

serratus posterior superior action

elevate ribs; mostly proprioceptive

serratus posterior superior innervation

intercostal nerves T2-T5

serratus posterior superior blood supply

posterior intercostal arteries

serratus posterior inferior origin

spinous process T11-L2

serratus posterior inferior insertion

angle of rib 8-12

serratus posterior inferior action

depress ribs; mostly proprioceptive

serratus posterior inferior innervation

intercostal nerves T9-T12

serratus posterior inferior blood supply

posterior intercostal arteries, the subcostal artery, and upper lumbar arteries

diaphragm origin

sternal part: posterior aspect of xiphoid process

costal part: internal surfaces of lower costal cartilages and ribs 7-12

lumbar part: medial and lateral arcuate ligaments (lumbocostal arches), bodies of vertebrae L1-L3 (+intervertebral discs), anterior longitudinal ligament

diaphragm insertion

central tendon of diaphragm

diaphragm action

depresses costal cartilages, primary muscle of inspiration (breathing)

diaphragm innervation

phrenic nerves (C3-C5), sensory innervation of peripheries via 6th-11th intercostal nerves

diaphragm blood supply

subcostal and lowest 5 intercostal arteries, inferior phrenic arteries, superior phrenic arteries

external oblique origin

ribs 5-12

external oblique insertion

linea alba, lateral lip of iliac crest

external oblique unilateral action

contralateral rotation, ipsilateral side bend

external oblique bilateral action

flex trunk, increase intra-abdominal pressure

external oblique innervation

anterior rami of T7-12

external oblique blood supply

lower posterior intercostals, subcostals, deep circumflex iliac artery

internal oblique origin

thoracolumbar fascia, iliac crest and inguinal igament

internal oblique insertion

linea alba, pubic crest, lower 3-4 ribs

internal oblique unilateral action

ipsilateral rotation, ipsilateral side bend

internal oblique bilateral action

flex trunk, increase intra-

internal oblique innervation

anterior rami of T7-12/L1

internal oblique blood supply

lower posterior intercostal and subcostal arteries, the superior and inferior epigastric arteries, the superficial and deep circumflex iliac arteries, posterior lumbar arteries

transversus abdominis origin

thoracolumbar fascia, iliac crest, inguinal ligament, lower 6 ribs

transversus abdominis insertion

linea alba, pubic crest, form the anterior rectus sheath (in lower abdominal region)

transversus abdominis bilateral action

increase intra-abdominal pressure

transversus abdominis innervation

anterior rami of T7-12, L1

transversus abdominis blood supply

lower posterior intercostal and subcostal arteries, superior and inferior epigastric arteries, deep and superficial circumflex arteries, posterior lumbar arteries

rectus abdominis origin

pubic crest, pubic tubercle, pubic symphysis

rectus abdominis insertion

xiphoid process, costal cartilage of ribs 5 to 7

rectus abdominis bilateral action

increase intra-abdominal pressure, flex spine, posterior pelvis rotation

rectus abdominis innervation

anterior rami of T7-12

rectus abdominis blood supply

superior epigastric artery, inferior epigastric artery

quadratus lumborum origin

iliac crest, iliolumbar ligament

quadratus lumborum insertion

inferior border of rib 12, transverse processes of vertebrae L1-L4

quadratus lumborum bilateral action

fixes rib 12 during inspiration, trunk extension

quadratus lumborum unilateral action

ipsilateral flexion of trunk

quadratus lumborum innervation

subcostal nerve T12, anterior rami of spinal nerves L1-L4

quadratus lumborum blood supply

lumbar, median sacral, iliolumbar and subcostal arteries

psoas major origin

vertebral bodies of T12-L4, intervertebral discs between T12-L4, transverse processes of L1-L5 vertebrae

psoas major insertion

lesser trochanter of femur as iliopsoas tendon

psoas major action

flexion of thigh/trunk, lateral rotation of the thigh, lateral flexion of the trunk

psoas major innervation

anterior rami of spinal nerves L1-L3

psoas major blood supply

lumbar branch of iliolumbar artery

iliacus origin

iliac fossa

iliacus insertion

lesser trochanter of femur

iliacus action

hip joint: thigh/trunk flexion

iliacus innervation

femoral nerve (L1-L3)

iliacus blood supply

iliolumbar, deep circumflex iliac, obturator, femoral artery

splenius capitis origin

ligamentum nuchae and spinous process of C7-T4

splenius capitis insertion

lateral third of superior nuchal line and mastoid process

splenius muscles unilateral action

ipsilateral lateral flexion and rotation of head (capitis) and neck (cervicis)

splenius muscles bilateral action

extend head (capitis) and neck (cervicis)

splenius capitis innervation

lateral branches of posterior rami of spinal nerves C2-C3

splenius capitis blood supply

muscular branches of occipital artery

splenius cervicis origin

spinous processes of T3-T6

splenius cervicis insertion

transverse process of C1-C3

splenius cervicis innervation

lateral branches of posterior rami of lower cervical spinal nerves

splenius cervicis blood supply

vertebral, occipital, superior intercostal, deep cervical, transverse cervical arteries

erector spinae: iliocostalis origin

iliac crest/lumbar fascia, posterior sacrum

erector spinae: iliocostalis insertion

angles of ribs (lumbar and thoracic), transverse processes C4-6

erector spinae: iliocostalis bilateral action

extension of spine

erector spinae: iliocostalis unilateral action

ipsilateral flexion of spine

erector spinae: iliocostalis innervation

lateral branches of posterior rami of spinal nerves

erector spinae: iliocostalis blood supply

cervicis: occipital, deep cervical and vertebral arteries

thoracis: dorsal branches of posterior intercostal and subcostal arteries

lumborum: dorsal branches of lumbar and lateral sacral arteries

erector spinae: longissimus origin

iliac crest, lumbar fascia, lumbar transverse processes (thoracis)

transverse processes upper thoracic (cervicis/capitis)

erector spinae: longissimus insertion

thoracic TPs/ribs (thoracis)

cervical TPs (cervicis)

mastoid (capitis)

erector spinae: longissimus action

bilateral: extension of spine

unilateral: ipsilateral flexion of spine

longissimus capitis only:

bilateral: extension of head and neck

unilateral: ipsilateral flexion and rotation of head

erector spinae: longissimus innervation

lateral branches of posterior rami of spinal nerves

erector spinae: longissimus blood supply

longissimus capitis and cervicis: vertebral artery, deep cervical artery, occipital artery, transverse cervical artery

longissimus thoracis: superior intercostal, posterior intercostal and subcostal arteries, lateral sacral and median sacral arteries

erector spinae: spinalis origin

spinous process upper lumbar and thoracic

erector spinae: spinalis insertion

spinous processes upper thoracic and cervical

erector spinae: spinalis innervation

lateral branches of posterior rami of the cervical, thoracic, and lumbar spinal nerves

erector spinae: spinalis blood supply

vertebral, deep cervical, occipital, intercostal, and lumbar arteries

erector spinae muscle group unilateral action

ipsilateral lateral flexion of vertebral column

• more lateral attachment, more oblique fiber direction, more contribution to SB

erector spinae muscle group bilateral action

extend head and vertebral column