Posterior branch of obturator nerve
The posterior branch of the obturator nerve pierces the anterior part of the Obturator externus, and supplies this muscle; it then passes behind the Adductor brevis on the front of the Adductor magnus, where it divides into numerous muscular branches which are distributed to the Adductor magnus and the Adductor brevis [Chung and Chung BRS Gross anatomy 7th edition].