Foramen through which the obturator internus exits the pelvis?

• A. Lesser sciatic foramen
• B. Greater sciatic foramen
• C. Obturator canal
• D. Pelvic brim

Answer: (A)

The obturator internus exits the pelvis through the lesser sciatic foramen. After arising from the inner surface of the obturator membrane and nearby bones, the tendon passes laterally and leaves the pelvic cavity via this opening, then wraps around the ischial spine to insert on the greater trochanter of the femur. This route places it into the gluteal region where it acts to laterally rotate the thigh.

The greater sciatic foramen is the pathway for structures like the piriformis and several gluteal nerves and vessels, not the obturator internus tendon. The obturator canal transmits the obturator nerve and vessels into the medial thigh, not the exit of the obturator internus. The pelvic brim is simply the boundary of the pelvic inlet.