The obturator nerve is the largest nerve from the anterior divisions of the lumbar plexus, receiving contributions from L2-4. The nerve courses through the psoas major, exiting on its medial aspect and running along the lateral wall of the lesser pelvis until it enters the obturator foramen. It then divides into an anterior and posterior division, supplying branches to the hip joint, adductor longus, adductor brevis, gracilis, adductor magnus and sensory innervation the medial thigh. While in the middle window of the ilioingunal approach, the lateral femoral cutaneous nerve (sensory innervation to lateral thigh) and femoral nerve (sensory innveration to anterior thigh and motor innervation for knee extension) will also be encountered and may be injured. Illustrations A and B demonstrate the course and sensory innervation of the aforementioned nerves, respectively.
Rohen JW, Yokochi C, Lütjen-Drecoll E. Color Atlas of Anatomy, 3rd ed. New York, NY: Ogaku Shoin Publishers; 2002:205-208.
Smith WR, Ziran BH, Morgan SJ, eds. Fractures of the Pelvis and Acetabulum, 2nd ed. New York, NY: Informa Healthcare Publishers; 2007:169-282.