Muscles of superificial back and pectoral region

external intercostals

Origin: inferior border of rib above insertion

Insertion: superior border of rib below origin

Function: contraction raises ribs during inhalation

Innervation: intercostal nerves

internal intercostals

Origin: superior border of rib below insertion

Insertion: inferior border of rib above origin

Function: draws ribs together during forced exhalation

Innervation: intercostal nerves

external oblique

Origin: inferior 8 ribs

Insertion: iliac crest and linea alba

Function: togeter; compress abdomen and flex vertebral column, alone; laterally flex same side and rotate opposite side

Innervation: intercostal nerves

internal oblique

Origin: iliac crest, inguinal ligament, thorocolumbar fascia

Insertion: cartilage of last 4 ribs and linea albe

Function: together; compress abdomen and flex vertebral column; alone; laterally flex and rotate same side

Innervation: intercostal nerves