Complex sentence: It arises from the dorsal divisions of the fourth and fifth lumbar and first sacral nerves: it leaves the pelvis through the greater sciatic foramen above the piriformis, accompanied by the superior gluteal artery and the superior gluteal vein.
Split into simpler sentences: It arises from the dorsal divisions of the fourth and fifth lumbar and first sacral nerves. It leaves the pelvis through the greater sciatic foramen above the piriformis, accompanied by the superior gluteal artery and the superior gluteal vein.