Which muscles arise from the sacrum and pass through the greater sciatic notch?

• A. Piriformis
• B. Obturator internus
• C. Iliopsoas
• D. Psoas major

Answer: (A)

The greater sciatic notch/foramen serves as the passage from pelvis to the gluteal region for muscles and other structures. The piriformis arises from the anterior surface of the sacrum and travels through the greater sciatic foramen to insert on the greater trochanter of the femur, making it the muscle that both originates in the sacrum and passes through that opening. The other muscles don’t fit this path: obturator internus comes from the inner obturator membrane and goes through the lesser sciatic foramen, while the iliopsoas and psoas major originate higher in the lumbar region/iliac fossa and pass under the inguinal ligament into the thigh.