abdominal wall and back muscles

what are the muscles of the abdominal wall

external/internal oblique, transversus/rectus abdominis, pyramidalis

external oblique action with bilateral contraction

flex trunk, compress abdomen

external oblique action with unilateral contraction

ipsilateral side bending, contralateral rotation

external oblique origin

ribs 5-12

external oblique insertion

linea alba

external oblique innervation

T7-T12

internal oblique action with bilateral contraction

flex trunk, compress abdomen

internal oblique action with unilateral contraction

ipsilateral trunk rotation and lateral flexion

internal oblique origin

thoracolumbar fascia

internal oblique insertion

linea alba, lower ribs

internal oblique innervation

T7-T12

transversus abdominis action with bilateral contraction

compress viscera (brace, valsalva)

transversus abdominis action with unilateral contraction

ipsilateral rotation

transversus abdominis origin

thoracolumbar fascia

transversus abdominis insertion

linea alba

transversus abdominis innervation

T6-L1

rectus abdominis action

compress abdomen, flex trunk, control ant/post pelvic tilt

rectus abdominis origin

pubic symphysis, pubic crest

rectus abdominis insertion

xiphoid process, costal cartilage 5-7

rectus abdominis innervation

T6-T12

pyramidalis action

tense linea alba, flex trunk slightly

pyramidalis origin

pubic symphysis

pyramidalis insertion

linea alba

pyramidalis innervation

T12

what are the superficial extrinsic back muscles

trapezius, latissimus dorsi, levator scapulae, rhomboid major/minor

superior fibers of trapezius action

elevate scapula

middle fibers of trapezius action

retract scapula

inferior fibers of trapezius action

depress scapula

superior and inferior fibers of trapezius action

upwardly rotate scapula

trapezius origin

EOP, nuchal line, C7-T12 spinous process

trapezius insertion

clavicle, acromion, scapular spine

trapezius innervation

spinal accessory nerve (CN 11)

latissimus dorsi action

extend, adduct, IR humerus

latissimus dorsi origin

thoracolumbar fascia

latissimus dorsi insertion

intertubercular/bicipital groove of humerus

latissimus dorsi innervation

thoracodorsal nerve (C6-C8)

levator scapulae action with bilateral contraction

elevate and retract scapula, extend neck

levator scapulae action with unilateral contraction

ipsilateral neck sidebend

levator scapulae origin

C1-4 transverse processes

levator scapulae insertion

medial border of scapula

levator scapulae innervation

dorsal scapular nerve (C4-C5)

rhomboid major action

retract, stabilize, downward rotate scapula

rhomboid major origin

T2-5 spinous processes

rhomboid minor action

elevate, retract, stabilize, downward rotation of scapula

rhomboid minor origin

C7 and T1 spinous processes

rhomboid major/minor insertion

medial border of scapula

rhomboid major/minor innervation

dorsal scapular nerve (C4-C5)

what are the intermediate extrinsic back muscles

serratus posterior superior/inferior

serratus posterior superior action

elevate ribs to aid inspiration

serratus posterior superior origin

C7-T3 spinous processes

serratus posterior superior insertion

superior borders of ribs 2-5

serratus posterior superior innervation

T2-T5

serratus posterior inferior action

depress ribs to aid forceful expiration

serratus posterior inferior origin

T11-L2 spinous processes

serratus posterior inferior insertion

inferior border of ribs 9-12

serratus posterior inferior innervation

T9-T12

serratus anterior action

protract and upwardly rotate scapula

serratus anterior origin

ribs 1-8

serratus anterior insertion

anterior surface of medial border of scapula

serratus anterior innervation

long thoracic nerve (C5-C7)

what are the superficial intrinsic back muscles

splenius capitis/cervicis

splenius capitis/cervicis action with bilateral contraction

extend neck

splenius capitis/cervicis action with unilateral contraction

ipsilateral neck sidebend, head rotation

splenius capitis/cervicis origin

C7-T6 spinous process, nuchal ligament

splenius capitis insertion

mastoid process, nuchal line

splenius cervicis insertion

C1-C4 transverse processes

splenius capitis/cervicis innervation

C2-C3 dorsal rami

what are the intermediate intrinsic back muscles

erector spinae: iliocostalis, longissimus, spinalis

erector spinae action with bilateral contraction

extend vertebral column

erector spinae action with unilateral contraction

ipsilateral sidebend

iliocostalis origin

broad tendon at base of spinal column, iliac crest

3 regions of spinalis

spinalis capitis/cervicis/thoracis

longissimus/spinalis origin

broad tendon at base of spinal column

iliocostalis insertion

angle of lower ribs, C transverse processes

longissimus insertion

tubercles of ribs, transverse processes, mastoid processes

spinalis insertion

C and T spinous processes, EOP

iliocostalis/longissimus/spinalis innervation

dorsal rami

what are the deep intrinsic back muscles

transversospinalis, interspinales, intertransversarii, levatores costarum

what muscles are part of the transversospinalis group

semispinalis, multifidus, rotatores

what are the semispinalis regions

semispinalis capitalis/cervicis/thoracis

semispinalis action with bilateral contraction

extend head and C spine

semispinalis action with unilateral contraction

contralateral rotation of spine at insertion

semispinalis origin

C4-T12 transverse processes

semispinalis insertion

occiput, C and T spinous processes

semispinalis innervation

dorsal rami

multifidus action with bilateral contraction

stabilize vertebrae, extend spine

multifidus action with unilateral contraction

contralateral rotation of spine

multifidus origin

PSIS, transverse processes

multifidus insertion

spinous processes of 2-4 levels superior to origin

multifidus innervation

dorsal rami

rotatores action

proprioception, stabilize vertebrae, limited contralateral rotation

rotatores origin

transverse processes

rotatores insertion

spinous processes of above vertebrae

longus: 2

brevis: 1

rotatores innervation

dorsal rami

interspinales action

vertebrae extension and stabilization during rotation

interspinales origin

spinous processes

interspinales insertion

spinous processes superior to origin

interspinales innervation

dorsal rami

intertransversarii action with bilateral contraction

stabilize

intertransversarii action with unilateral contraction

lateral sidebend