Origin External surface of obturator membrane and anterior bony margins of obturator foramen Insertion Trochanteric fossa on the medial surface of the greater trochanter Action Rotates the thigh laterally; also helps adduct thigh Innervation Posterior division of obturator nerve innervates most of the obturator externus; (L3, L4) Arterial Supply Obturator and medial circumflex femoral arteries