The posterior femoral cutaneous nerve (small sciatic nerve) is distributed to the skin of the perineum and the back surface of the thigh and leg. It stems from the sacrum and leaves the pelvis through the greater sciatic foramen (opening in the bone). It accompanies the inferior gluteal artery to the gluteus maximus (large muscle in the buttocks) and runs down the outer thigh and deep into the tissuemycontentbreak at the back of the knee. It accompanies the small saphenous vein to the middle of the back of the leg.