MUSCLES OF THE PELVIS. 493 



ichannel. The fascial fold is composed of two layers, posterior and superior, 

 ! between which is a large plexus of veins. They have separate attachments 

 laterally to the general pelvic fascia. The posterior (recto-vesical) layer passes 

 across the pelvis between the prostate gland and the rectum. Its inferior edge 

 is attached to the perineal body between the base of the fascia of the urogenital 

 diaphragm and the beginning of the anal canal. It forms a sheath for the 

 vesiculse seminales and ductus deferentes. This is rather in the form of a septum 

 | than a complete sheath ; it effectually separates the vesiculse seminales and the 

 bladder from the rectum, forming the anterior wall of the rectal channel, but it 

 allows the vesiculse seminales to rest directly against the bladder. The superior 

 layer extends forwards to the symphysis pubis. It has a lateral origin from the 

 arcus tendineus in its whole length, and sweeping over the prostate gland, it is 

 inserted along its line of junction with the bladder, and constitutes the so-called 

 lig. puboprostaticum laterale (lateral true ligament of the bladder). It contains 

 numerous bundles of muscular fibres in its anterior part, and forms a sheath 

 for the passage of the inferior vesical vein along the lateral surface of the 

 prostate gland. In front the fascia stretches from the back of the symphysis 

 pubis, the arcuate ligament of the pelvis, and the superior fascia of the uro- 

 genital diaphragm to the neck of the bladder and the prostate gland, forming the 

 lig. puboprostaticum medium. It is continuous across the median plane with the 

 ligament of the opposite side. In the median line, where the two ligaments 

 unite, a hollow occurs behind the symphysis pubis, known as the cavum Betzii. 

 This ligament is composed of several layers separated by large veins (the pudendal 

 plexus), which connect the inferior vesical vein with the dorsal vein of the penis 

 and the hypogastric vein. 



The sheath of the prostate gland (fascia prostatae) is formed by (1) the superior 

 fascia of the urogenital diaphragm on which it lies, (2) by the general pelvic fascia 

 covering the intra-pelvic surfaces of the levatores aid on each side, and (3) it is 

 completed above and behind by the two special layers of pelvic fascia just 

 described. By these means the prostate gland and prostatic urethra are given a 

 firm attachment to the anterior part of the pelvic walls and floor. 



In the female an essentially similar arrangement of the pelvic fascia occurs in 

 relation to the vagina and urethra. A crescentic fold of the fascia springs from 

 the pelvic wall in the neighbourhood of the spina ischiadica, and sweeping medially 

 to the lateral fornix of the vagina and in front of the rectum, separates into two 

 | layers, posterior and superior. Between the layers are numerous vessels, which, 

 I along with the visceral nerves, pierce 'its free edge. The posterior (recto-vaginal) 

 layer passes medially behind the vagina, and gaining the median plane between 

 the vagina and rectum, gives rise to the anterior wall of the rectal channel, and 

 is attached below to the perineal body in the floor of the pelvis. The superior 

 layer, taking origin from the arcus tendineus, is attached medially to the neck of 

 the bladder, and constitutes the lateral pubo-vesical ligament. It is continuous in 

 front with the anterior pubo-vesical ligament, which, as in the male, is divisible into 

 several layers separated by veins. An intermediate (urethro-vaginal) layer of the 

 , fascia passes between and separates the urethra and vagina. 



The urethra and vagina are by means of these layers of fascia firmly bound to 

 the pelvic walls and floor, while the uterus and bladder are free to distend in the 

 pelvic cavity. 



MUSCLES OF THE PELVIS. 



Diaphragma Pelvis. The pelvic diaphragm is formed by the levator ani 

 and coccygeus muscles, which serve to uphold the pelvic floor, and are related to 

 the rectum and the prostate gland or vagina. 



M. Levator Ani. The levator ani arises from (1) the inferior part of the 

 >sterior surface of the body of the pubis, (2) the general pelvic fascia above or 

 -ong the arcus tendineus, and (3) the pelvic surface of the spine of the ischium. 

 Us fibres are directed downwards and backwards, to be inserted into (1) the 

 tral point of the perineum (perineal body), (2) the external sphincter around 





