week 2 - thoracic and abdominal wall muscles

sternocleidomastoid origin

sternal: upper part of anterior surface of manubrium of sternum

clavicular: superior surface of medial 1/3 of clavicle

sternocleidomastoid insertion

sternal: lateral 1/2 of superior nuchal line

clavicular: lateral surface of mastoid process

sternocleidomastoid action

individually: tilt head toward shoulder on same side, rotating head to turn face to opposite side

acting together: draw head forward

sternocleidomastoid innervation

Accessory nerve [XI] and branches from anterior rami of C2 to C3 (C4)

internal intercostal origin

lateral edge of costal groove of rib above

internal intercostal insertion

superior margin of rib below, deep to attachment of related external intercostal

internal intercostal action

most active during expiration, supports intercostal space, moves ribs inferiorly

internal intercostal innervation

intercostal nerves (T1-T11)

external intercostal origin

inferior margin of rib above

external intercostal insertion

superior margin of rib below

external intercostal action

Most active during inspiration; supports intercostal space; moves ribs superiorly

external intercostal innervation

intercostal nerves (T1-T11)

diaphragm origin

xiphoid process of sternum, internal surfaces of 7th-12th costal cartilages/adjacent ribs, medial and lateral arcuate ligaments, L1-L3

diaphragm insertion

central tendon

diaphragm action

primary muscle of inspiration

diaphragm innervation

motor: phrenic nerves (C3-C5)

sensory: phrenic nerves and lower intercostal nerves

external oblique origin

Muscular slips from the outer surfaces of the lower eight ribs (ribs 5-12)

external oblique insertion

lateral lip of iliac crest, aponeurosis ending in midline raphe (linea alba)

external oblique action

compress abdominal contents, flex trunk, each muscle bends trunk to same side, turning anterior part of abdomen to opposite side

internal oblique origin

thoracolumbar fascia, iliac crest between origins of external and transversus, lateral 2/3 of inguinal ligament

internal oblique insertion

inferior border of lower 3-4 ribs, aponeurosis ending in linea alba, pubic crest and pectineal line

internal oblique action

compress abdominal contents, both muscles flex trunk, each muscle bends trunk to same side, turning anterior part of abdomen to same side

transversus abdominis origin

Thoracolumbar fascia; medial lip of iliac crest, lateral 1/3 of inguinal ligament; costal cartilages of inferior six ribs (7-12)

transversus abdominis insertion

Aponeurosis ending in linea alba; pubic crest and pectineal line

transversus abdominis action

compress abdominal contents

rectus abdominis origin

Pubic crest, pubic tubercle, and pubic symphysis

rectus abdominis insertion

costal cartilages of ribs 5-7, xiphoid process of sternum

rectus abdominis action

compress abdominal contents, flex vertebral column, tense abdominal wall