PELVIS MINOR 421 



and carried from side to side. In that way it is possible to 

 demonstrate that the visceral layer of the pelvic fascia, as it 

 descends on the levator ani, divides into a lower layer, which 

 passes behind the rectum, and a layer which passes between the 

 rectum and the prostate the recto-vesical layer (Fig. 195). 



The right levator ani must now be divided, from before 

 backwards, about midway between its origin from the parietal 

 fascia and its insertion into the wall of the anal passage, care 

 being taken to avoid injury to the fascia on its upper surface. 

 The lower part of the muscle should be followed to its insertion 

 into the wall of the anal canal, and the mode of insertion between 

 the internal and the external sphincters noted. The upper part 

 should be turned laterally and the fingers of the left hand passed 

 along its upper surface till its origin from the fascia is reached. 

 When that is done the dissector will find that the only structure / 

 which separates his fingers from the cavity of the pelvis is the / 

 upper layer of the fascia of the pelvic diaphragm (visceral layer 

 of the pelvic fascia) , which extends from the parietal fascia, at 

 the level of the origin of the levator ani, and passes medially / 

 to the walls of the viscera, which it ensheathes. If the dissector 

 will now place the fingers of one hand on the upper surface of 

 the visceral fascia and those of the other hand on the lower 

 surface, and then carry both hands medially, he will find that the 

 one hand passes on to the upper surface of the bladder and the 

 other behind the rectum. He will thus demonstrate that as the 

 visceral fascia crosses the pelvis from side to side it separates into 

 an upper or vesical layer and a lower or rectal layer. The 

 third or recto-vesical layer, which covers the posterior surface 

 of the prostate, and separates the gland from the rectum, has 

 already been demonstrated. The recto-vesical layer must now be 

 incised, in the median plane, on the posterior surface of the 

 prostate and each half must be turned laterally. As the borders 

 of the prostate are approached a plexus of veins will be exposed 

 on each side, and immediately beyond the plexus the recto- 

 vesical layer of the fascia will be found to blend with the vesical 

 layer, which passes over the upper surface of the prostate. The 

 ductus deferentes and the seminal vesicles will be exposed when 

 the reflection of the recto-vesical layer is carried backwards 

 beyond the prostate (Fig. 196). 



The True Ligaments of the Bladder. There are five so- 

 called true ligaments of the bladder : two lateral, the lateral 

 pubo-vesical ligaments ; two anterior, the medial pubo-vesical 

 ligaments (pubo-prostatic in the male) ; and one superior. 

 The lateral are the lateral parts of the vesical layer of pelvic 

 fascia. The anterior are two thickenings of the same layer, 

 one on each side of the median plane, in front of the bladder ; 

 they contain smooth muscle fibres which pass from the 

 bladder to the back of the pubic bones at the margins of the 

 symphysis. The superior, the lig. umbilicale medium, is the 

 urachus. 



During the various stages of this dissection the student 

 n27 b 



