THE PELVIS. 



435 



prostate. The anterior edge of the levator ani muscle reaches to the central tendon 

 of the perineum (Fig. 442). 



Pelvic Herniae. Hernial protrusions of the pelvic contents may occur through 

 the upper portion of the obturator membrane, following the vessels and nerve. This 

 is called an obturator hernia. The sac is usually to the medial or inner side of the 

 vessels and nerve. It makes its appearance in Scarpa's triangle and is covered by 

 the pectineus muscle. Death has frequently occurred in these cases from strangula- 

 tion. Sciatic hernia is the name given to those forms in which the intestine escapes 

 through the great sciatic notch, passing just above or just below the pyriformis 

 muscle. Perineal hernia are those which work their way downward in other places. 

 Thus the sac may push down between the rectum and bladder and bulge in the 

 perineum. It may pass between the coccygeus and levator ani muscles or between 

 the fibres of the latter and bulge into the ischiorectal fossa, or forward into the labium 

 of the female. 



Prolapse. The rectum and vagina as they pierce the pelvic floor may pro- 

 lapse or protrude through the anus or vulva. Prolapse of the rectum is a common 



Pvriformis~, 



Coccygeus muscle -H 



Spine of ischium 



Cut edge of levatpr ani in 

 middle line 



Levator ani muscle 



Iliopectineal line 

 Obturator internus 

 Obturator foramen 



White line 



Bladder 

 Uterus 



Vagina -""^ * Sa*! 



FIG. 442. Levator ani muscle and interior of pelvis; the bladder, uterus and vagina, and rectum have been 



loosened and turned down. 



affection and if marked may drag down the peritoneum so that some coils of small 

 intestine may be around the prolapsed part. In childbirth the pelvic outlet is fre- 

 quently torn and the vagina prolapses and may drag the uterus down with it, or, the 

 support being lost, the uterus descends and drags the vagina with it and everts it. 

 The vaginal outlet, if much relaxed, allows the rectum to bulge downward and for- 

 ward, forming a rectocele, or the bladder may bulge downward and backward, forming 

 a cystocele (see Fig. 466, page 463). 



The Pelvic Fasciae. As the iliac fascia passes over the brim of the pelvis it 

 covers the internal obturator muscle on the walls of the pelvis, hence it is called 

 the obturator fascia. From the upper posterior surface of the arch of the pubes 

 anteriorly to the spine of the ischium posteriorly this obturator fascia is thickened, 

 forming the " white line" to give origin to the levator ani muscle. At the white 

 line the obturator fascia gives off a visceral layer the rectovesical fascia which 

 covers the inner or upper surface of the levator ani, then a second layer, the anal 

 fascia, covering the under or outer surface of the levator ani muscle, while the 

 obturator fascia itself is continued down on the obturator internus muscle to form 



