552 A MANUAL OF ANATOMY. 



branches, one from the lumbosacral cord and the other from 

 the first sacral nerve. It passes out of the pelvis with the 

 gluteal artery, through the great sacrosciatic foramen and 

 above the pyriformis muscle, supplies the gluteus medius 

 and minimus, between which it runs forward to terminate 

 in the tensor vaginae femoris. () The inferior gluteal, 

 formed by filaments from the lumbosacral cord, the first and 

 second sacral nerves, leaves by the same foramen as the 

 above, only below the pyriformis muscle (where it is usually 

 contained in the same sheath with the small sciatic nerve, giv- 

 ing rise to the statement that it is a branch of the small sci- 

 atic), and terminates in the gluteus maximus muscle, (c) 

 The branch to the pyriformis muscle is from the second and 

 third sacral nerves, (d} The nerve to the quadratus femoris 

 arises from the third sacral nerve, passes through the great 

 sacrosciatic foramen below the pyriformis muscle, descends 

 in front (anterior to) the obturator internus and gemelli 

 muscles to be distributed to the anterior surface of the 

 quadratus femoris muscle. In its passage over the hip- 

 joint it sends a branch to it. (e) The small sciatic nerve 

 comes from the posterior surface of the second and third 

 sacral nerves, makes its exit from the pelvis through the 

 great sacrosciatic foramen below the pyriformis muscle. 

 For the rest of its course, see page 604. (/) The nerve 

 to the obturator internus arises from the second and third 

 sacral nerves, goes out through the great sacrosciatic fora- 

 men under the pyriformis, re-enters the pelvis through the 

 smaller sacrosciatic foramen, and is distributed to the mus- 

 cle from which it is named, (g) The internal pudic arises 

 by three roots from the second, third, and fourth sacral 

 nerves, takes the same course as the nerve above until the 

 pelvis is re-entered, it then follows along with the internal 

 pudic artery through the canal (Alcock's) beneath the 



