THE FASCIAE OF THE PERINEUM AND PELVIS. 339 



constrictor muscle of the urethra, and Cowper's glands, together with the pudic 

 vessels and their offsets to the bulb, and the dorsal nerves of the penis. The 

 superior or deep layer consists of right and left lateral halves, which are separated 

 in the middle line by the urethra close to the neck of the prostate, where they are 

 continued into the sheath of that gland derived from the recto-vesical portion of 

 the pelvic fascia, whilst laterally they join on each side the obturator portion of the 

 pelvic fascia close to its attachment to the pubic and ischial rami. This layer of 

 fascia is superficial to the anterior fibres of the levator ani muscle, which lie between 

 it and the recto-vesical fascia, and it is connected with a thin web of areolar tissue 

 which extends backwards on the surface of the levator ani muscle, and is dis- 

 tinguished as the anal fascia. 



In the female the deep perineal fascia is divided in the middle by the vagina. 



FASCIA OF THE PELVIS. The pelvic fascia is a complicated structure lining 

 the muscles within the cavity of the pelvis and supporting the pelvic viscera. It 

 consists of two principal parts, which are known as the obturator fascia and the 

 recto-vesical fascia. 



The obturator fascia, a distinct piece on each side of the pelvis, may be 

 regarded as the special fascia of the obturator internus muscle, the inner surface of 

 which it covers, and around which it is fixed to the bone. It is attached above for 

 a short distance to the iliac portion of the ilio-pectineal line ; in front, to the body 

 of the pubis along an oblique line extending from the upper and inner part of the 

 thyroid foramen to a little below the symphysis ; behind, to the anterior margin of 

 the ilio-sciatic notch, as well as to the great sacro-sciatic ligament ; and below, it 

 joins the falciform process of that ligament, by means of which it is connected to 

 the ischial and pubic rami. At the upper end of the thyroid foramen its attach- 

 ment to the bone is interrupted, and the fascia joins the upper edge of the obturator 

 membrane, forming an arch over the border of the muscle, and bounding below the 

 short canal by which the obturator vessels and nerve issue. The inner surface of 

 this fascia in its upper part looks into the pelvic cavity and is lined by peritoneum ; 

 in its lower part it looks into the perineal space, forming the outer boundary of the 

 ischio-rectal fossa, and in this part of the fascia the internal pudic vessels with 

 their accompanying nerves are embedded in a sheath as they course to the front of 

 the perineum. 



The fascia of the pyriformis is a thin and unimportant layer, which is continued 

 backwards from the obturator fascia to the sacrum, passing in front of the pyriformis 

 muscle and the nerves of the sacral plexus, and being perforated by the branches of 

 the internal iliac vessels which leave the pelvis by the great sacro-sciatic foramen. 



The recto-vesical fascia is attached anteriorly to the back of the pubis above 

 the obturator fascia, from which it is here separated by the origin of the levator 

 ani, the three being, however, generally closely adherent near the bone ; laterally it 

 springs from the obturator fascia along a curved line passing from the upper part of 

 the obturator foramen to the ischial spine ; and posteriorly it becomes continuous 

 with the lower part of the fascia of the pyriformis. From these attachments the 

 fascia is directed downwards and inwards, in contact with the upper surface of the 

 levator ani muscle, to the prostate gland, to the bladder, and to the rectum, and 

 being farther continuous from side to side across the middle line in front of the 

 bladder and between the bladder and the rectum, it thus forms a fibrous partition 

 which completely separates the pelvic cavity above from the perineal space below. 

 Certain parts of this fascia, generally not very well defined, however, are referred to 

 as ligaments of the viscera with which they are connected. The best marked of 

 these are the anterior true ligaments of the bladder or pubo-prostatic ligaments, a narrow 

 but strong band on each side, consisting in great part of involuntary muscular fibres, 

 and passing from the lower part of the pubis to the anterior surface of the prostate 



VOL. II. Z 



