The obturator internus is innervated by which nerve?

• A. Anterior division of obturator nerve
• B. Nerve to obturator internus
• C. Posterior division of obturator nerve
• D. Sciatic nerve

Answer: (B)

The muscle known as obturator internus is supplied by a dedicated nerve called the nerve to obturator internus. This nerve arises from the sacral plexus (ventral rami L5–S2) and specifically innervates obturator internus, and also the superior gemellus. It’s distinct from the obturator nerve proper, whose anterior and posterior divisions mainly supply the medial thigh adductors, not the obturator internus. The sciatic nerve handles the posterior thigh and most of the leg, not this pelvic muscle. So, the nerve to obturator internus is the correct innervation.