How does the piriformis exit the pelvis?

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

Answer: (B)

The piriformis leaves the pelvis through the greater sciatic foramen. This opening, formed by the pelvic bones and ligaments (notably the sacrospinous and sacrotuberous ligaments), provides the main passage from the pelvic cavity into the gluteal region. The piriformis originates on the anterior surface of the sacrum and courses laterally to insert on the greater trochanter, crossing the pelvic wall as it exits. The lesser sciatic foramen lies below it and carries other structures (like the tendon of obturator internus and the pudendal vessels and nerve) on their way to the perineum, while the obturator canal and inguinal canal transmit different structures entirely. So, the exit route is the greater sciatic foramen.