356 THE ABDOMEN AND PELVIS 



The obturator internus arises from the posterior part of the 

 ilio-pectineal line, and over this area the parietal pelvic fascia 

 is directly continuous with the abdominal fascia covering the 

 psoas major (p. 271). More anteriorly, the upper border of 

 the obturator internus gradually sinks to a lower level and 

 carries the parietal pelvic fascia with it ; so that the inner 

 surface of the superior ramus of the pubis is left uncovered by 

 fascia or muscle. Opposite the obturator foramen, the fascia 

 is carried over the upper border of the obturator internus 

 and blends with the upper margin of the obturator membrane. 

 In the region of the pubic arch it forms the superior fascia of 

 the urogenital diaphragm (deep layer of triangular ligament] 

 (Fig. 115), and its upper border blends with the upper border of 

 the inferior fascia of the urogenital diaphragm (p. 378), leaving 

 a small interval below the pubic symphysis for the passage of 

 the dorsal vein of the penis. 



The lower margin of the parietal pelvic fascia blends, in 

 front, with the free edge of the inferior fascia of the urogenital 

 diaphragm and the fascia of Colles (p. 376) ; posteriorly, it 

 is attached to the sacro-tuberous ligament and the ischial 

 tuberosity. 



The Pelvic Diaphragm stretches across the cavity of the 

 pelvis, dividing it into an upper part, the pelvis proper, and a 

 lower part, which is dealt with under the Perineum (p. 373). 

 It is formed by the two levatores ani and coccygei, with the fascia 

 covering them, but it is incomplete, as gaps are left for the 

 passage of the anal canal and the urethra and, in the female, 

 for the vagina also. 



The Levator Ani has a linear origin from the side wall of the 

 pelvis. Its posterior fibres are attached to the ischial spine ; 

 the intermediate fibres arise from the parietal pelvic fascia 

 along a line extending from the ischial spine to the anterior 

 border of the obturator foramen. The anterior fibres arise 

 from the pelvic surface of the body of the pubis above the level 

 of the parietal pelvic fascia, but they do not extend as far as 

 the symphysis. 



The posterior fibres pass medially and are inserted into the 

 coccyx. In front of that point the muscles of the two sides 

 meet in a median raphe and form a muscular sling, which 

 supports the lower end of the rectum. The anterior fibres pass 

 backwards lateral to the prostate, which separates them from 

 the muscle of the opposite side, and they extend downwards 



