120 



DISSECTION OF THE BUTTOCK. 



Great sciatic 

 nerve : 



outline of ; 



ischial tuberosity, and perforates the fascia lata at the inner side 

 of the thigh to end in the scrotum. 



The GREAT SCIATIC (fig. 48, 6 ) is the largest nerve in the body. 

 It is the source of all the muscular, and most of the cutaneous 



Fia. 49. DIAGRAM OF THE SACRAL PLEXUS FROM BEHIND. 



LSC. Lumbo-sacral cord formed 

 by the fifth lumbar nerve and a 

 small branch from the fourth. 



SI to S 5. First to fifth sacral 

 nerves. 



g s. Great sciatic nerve. 



s s. Small sciatic. 



s g. Superior gluteal. 



i g. Inferior gluteal. 



p. Pudic. 



p c. Perforating cutaneous. 



py. Branch to pyriformis. 



o i. Nerve to obturator intern us. 



q. Nerve to quadratus femoris. 



course in 

 the buttock 



no bran chin 

 this region. 



The remaining references are explained in the dissection of the plexus in 

 the pelvis. 



branches to the limb beyond the knee, as well as of the muscular 

 branches at the back of the thigh. 



At its origin it appears to be a prolongation of the sacral plexus 

 (fig. 49, g s). It is directed through the buttock to the back of 

 the thigh, and rests, in succession, on the superior gemellus, the 

 tendon of the obturator interims, the inferior gemellus and the 

 quadratus fenioris muscles below the pyriformis. Commonly it 

 does not supply any branch to the buttock, but it may give origin 



