234 CIRCULATORY SYSTEM. 



nerve. It goes downwards on the back of the thigh, between 

 the trochanter major and the tuberosity of the ischium, being 

 at the internal edge of the sciatic nerve, and on the posterior 

 face of the small rotator muscles of the thigh. It sends off in 

 the pelvis the internal Pudic Artery, and also some inconstant 

 branches, of small size, to the viscera within the pelvis; when 

 it has emerged from the latter, it detaches some considerable 

 branches to the origin and to the inferior margin of the glu* 

 teus magnus muscle, and to the small rotator muscles. The 

 branch which may be considered as the continued trunk of the 

 ischiatic, descending on the posterior face of the thigh, along 

 with the sciatic nerve, under the hamstring muscles, is lost in 

 ramifications to them, and by anastomoses with the perforating 

 arteries. 



The Internal Pudic Artery, (flrleria Pudica Internet,) though 

 a branch of the ischiatic, is only in a slight degree smaller. It 

 arises a little above the spinous process of the ischium, in the 

 pelvis, in front of the sciatic plexus, and gstting from the pelvis 

 between the anterior sacro-sciatic ligament and the inferior 

 margin of the pyriformis muscle, it passes over the posterior 

 face of the anterior sacro-sciatic ligament, at the spinous pro- 

 cess of the ischium. It immediately afterwards returns into 

 the cavity of the pelvis, between the two sacro-sciatic liga- 

 ments, at the place where the obturator internus muscle winds 

 over the ischium; it then goes along the internal face of the 

 latter bone and of its ascending ramus, at the inferior margin 

 of the obturator internus muscle; and continues on the internal 

 face of the ramus of the pubes, between the two Iamina3 of the 

 triangular ligament, above the crus of the penis to the symphy- 

 sis of the pubes. 



In this course the Internal Pudic Artery detaches several im- 

 portant branches, in the following order: 



a. A ramification along the inferior margin of the pyriformis, 

 to this muscle and to the parts on the posterior face of the neck 

 of the os femoris, where it anastomoses with the other arteries 

 of this region. 



b. The Lower Hasmorrhoidnl Artery (JUrt. H&morrhoidca I?i- 

 ferior Extern a) to the inferior part of the rectum, and to the 

 external sphincter ani muscle. This artery arises after the inter- 



