THE SACRAL AND COCCYGEAL NERVES 



959 



The Nerve to the Piriformis arises from the dorsal division of the second sacral 

 nerve, or the dorsal divisions of the first and second sacral nerves, and enters 

 the anterior surface of the muscle; this nerve may be double. 



Sympathetic 

 trunk 



FIG. 829. Dissection of side wall of pelvis showing sacral and pudendal plexuses. (Testut.) 



The Superior Gluteal Nerve (n. glutcaus superior) 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 vessels, and divides into a superior and an inferior branch. The superior 

 branch accompanies the upper branch of the deep division of the superior gluteal 

 artery and ends in the Glutseus minimus. The inferior branch runs with the lower 

 branch of the deep division of the superior gluteal artery across the Glutseus 

 minimus; it gives filaments to the Glutaei medius and minimus, and ends in the 

 Tensor fasciae latte. 



The Inferior Gluteal Nerve (n. glutceus inferior} arises from the dorsal divisions 

 of the fifth lumbar and first and second sacral nerves : it leaves the pelvis through 

 the greater sciatic foramen, below the Piriformis, and divides into branches which 

 enter the deep surface of the Glutaeus maximus. 



The Posterior Femoral Cutaneous Nerve (n. cuto.neus femoralis posterior; small 

 sciatic nerve) is distributed to the skin of the perineum and posterior surface of 

 the thigh and leg. It arises partly from the dorsal divisions of the first and second, 

 and from the ventral divisions of the second and third sacral nerves, and issues from 



