Muscle: internal abdominal obliques (next deep layer to the external of the 3 anterolateral abdominal wall muscles)
fibers: run perpendicular to thos of the external oblique, they vary along the length of the muscle.
origin: spine via thoracocolumbar fascia, ant. 2/3 of iliac crest, connective tissue dep to the inguinal ligament
insertion: inferior borders of 10-12 ribs, linea alba, and pubis via conjoint tendon
innervation: thoraco-abdominal nerves (ant. rami T7-T11) and first lumbar nerve
action: compress and support abdominal viscera; flex and rotate trunk