Which nerve innervates the quadratus femoris muscle?

• A. Nerve to Quadratus Femoris
• B. Superior Gluteal Nerve
• C. Sciatic Nerve
• D. Obturator Nerve

Answer: (A)

Quadratus femoris is one of the deep external rotators of the hip, located in the posterior hip region. It is innervated by the nerve to quadratus femoris, a branch of the sacral plexus that specifically supplies this muscle and the inferior gemellus. This nerve is dedicated to this small group of rotators, helping with external rotation and stabilization of the femoral head.

The other nerves have different targets: the superior gluteal nerve goes to gluteus medius and minimus (and tensor fasciae latae), the sciatic nerve supplies the posterior thigh muscles (and most leg muscles), and the obturator nerve innervates the medial thigh adductors. Hence, the nerve to quadratus femoris is the correct innervation for this muscle.