Summary Obturator externus Origin Anterior 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 (L3, L4) Arterial supply Obturator and medial circumflex femoral arteries