2 – Anatomy of the obturator nerve

The obturator nerve origins from the spinal nerve roots L2-L4 of the lumbar plexus. It descends along the medial side of the psoas major in the lumbar paravertebral space, runs across the sacral ala and enters the lesser pelvis and the obturator canal along with the obturator artery and vein.

It innervates the external obturator and splits into an anterior and a posterior branch that run anterior and posterior to the adductor brevis respectively.

The anterior branch innervates the adductor longus, adductor brevis, gracilis and pectineus. And a variable small skin area on the medial side of thigh. The pectineus is also innervated by the femoral nerve. The medial part of the hip joint is innervated by the anterior branch or the common obturator nerve.

The posterior branch innervates the adductor magnus. The adductor magnus is also innervated by the sciatic nerve. The posterior branch descends through the adductor hiatus and innervates the posterior part of the knee capsule. The cruciate ligaments of the knee are innervated by the terminal posterior branch.