Muscles of the Body Wall/Back

external intercostal

external intercostal: origin

lower margin of upper rib

external intercostal: insertion

upper margin of lower rib

external intercostal: principle action(s)

raise ribs during inspiration

internal intercostal

internal intercostal: origin

upper margin of lower rib

internal intercostal: insertion

lower margin of upper rib

internal intercostal: principle action(s)

lower ribs during forced expiration

rectus abdominis

rectus abdominis: origin

pubis

rectus abdominis: insertion

costal cartilage of ribs 5-7, xiphoid process

rectus abdominis: principle action(s)

flex trunk, compress abdomen, stabilize pelvis

external oblique

external oblique: origin

ribs

external oblique: insertion

iliac crest, linea alba

external oblique: principle action(s)

flex trunk, compress abdomen, stabilize pelvis

internal oblique

internal oblique: origin

iliac crest

internal oblique: insertion

ribs

internal oblique: principle action(s)

flex trunk, compress abdomen, stabilize pelvis

transversus abdominis

transversus abdominis: principle action(s)

compress abdomen

quadratus lumborum (QL)

quadratus lumborum (QL): origin

iliac crest

quadratus lumborum (QL): insertion

transverse process L1-L4, 12th rib

quadratus lumborum (QL): principle action(s)

bearing down, expiration, stabilize 12th rib

diaphragm

diaphragm: origin

ribs 7-12, xiphoid process, body of vertebrae L1-L3

diaphragm: insertion

central tendon of diaphragm

diaphragm: principle action(s)

principle muscle of respiration

splenius capitis

splenius capitis

splenius capitis: principle action(s)

lateral flexion of neck, rotate head to same side

semispinalis capitis

semispinalis capitis

semispinalis capitis: principle action(s)

lateral flexion of neck, rotate head to same side

spinalis

spinalis: principle action(s)

extend vertebral column

longissimus

longissimus: principle action(s)

extend vertebral column

iliocostalis

iliocostalis: principle action(s)

extend vertebral column