chap, xviii.] THE PELVIS. 341 



The floor of the pelvis and the pelvic fascia. 



The outlet of the bony pelvis is occupied in the 

 recent state with the following structures from behind 

 forwards : the pyriformis, the sacro-sciatic ligaments, 

 the coccygeus, the levator ani, and the triangular 

 ligament of the urethra. These form the floor of the 

 pelvis. The three structures last named serve to 

 separate the pelvic cavity from the perineum. 



The walls and floor of the pelvis are lined by a 

 fascia, the pelvic fascia, of which a brief general 

 description may be given. This fascia is divided into 

 two distinct parts, a parietal layer and a visceral 

 layer. (1) The parietal layer begins at the brim of 

 the true pelvis, to which it is attached. From this 

 attachment it passes down along the pelvic wall, forming 

 a lining for that part, covering in the obturator internus 

 muscle, and becoming adherent below to the rami of 

 the pubes and ischium, and to the tuber ischii. More 

 posteriorly it gives a thin covering to the pyriformis 

 muscle. (2) The visceral layer comes off from 'the 

 parietal along a line running from the lower 

 part of the symphysis pubis to the ischial spine. 

 This line is known as the white line, and corre- 

 sponds to the origin of the levator ani from the pelvic 

 fascia. 



Starting from this line the visceral layer passes 

 down into the pelvis on the abdominal surface of the 

 levator am, and attaches itself to all the pelvic viscera 

 with which it comes in contact, forming fibrous expan- 

 sions or "ligaments," that serve to hold the viscera in 

 place. Were there no pelvic viscera, this layer of 

 the fascia would be continued evenly across the pelvic 

 floor from one side to the other, just as the subperi- 

 toneal fascia is continued over the under surface of 

 the diaphragm. Having given "reflections" to the 

 pelvic organs the visceral layer passes on, and, covering 

 the opposite levator muscle, ends at the opposite white 



