Internal obturator muscle it surrounds the greater part of the obturator foramen, being attached to the inferior pubic ramus and ischium, and at the side to the inner surface of the hip bone below and behind the pelvic brim, reaching from the upper part of the greater sciatic foramen above and behind to the obturator foramen below and in front. It also arises from the pelvic surface of the obturator membrane except in the posterior part, from the tendinous arch which completes the canal for the passage of the obturator vessels and nerve, and to a slight extent from the obturator fascia, which
Aphanosauria "Marasuchus" (other avemetatarsalians) have their ischia only slightly contact at the middle portion of each bone. The tip of the ischium is also rounded and semi-triangular in cross-section, with the lateral (outer) face of each ischium thinning towards the lower edge of the bone while the medial (inner) face is flat and contacts the other ischium. Poposauroids and dinosaurs also have rounded ischia, but lack the semi-triangular shape, which is also known in "Asilisaurus". The ischium also has a groove on the upper part of the shaft. Unlike dinosaurs, aphanosaurs have an acetabulum (hip socket) which is closed up by