Internal Abdominal Oblique

The Internal Abdominal Oblique fibers above the ASIS run a superomedial course from the inguinal ligament, crest of the ilium, and lower ribs to the posterior layer of the rectus sheath. Its fibers below the level of the ASIS run an inferomedial course. The inferior muscle fibers form the cremaster (middle spermatic fascia). Its aponeurosis continues to the pubic crest and contributes to the anterior and posterior layers of the rectus sheath.