The internal abdominal oblique muscle lies deep to the external oblique abdominal muscle. Its fibers run superomedially - perpendicular to the fibers of the external oblique, and its fibers are smaller and thinner in structure. Like the external abdominal oblique muscle, the internal abdominal oblique muscle also forms an aponeurosis in the medial direction towards the linea alba. It is called internal oblique aponeurosis.