RECTO-VESICAL FASCIA. 383 



anterior fibres, few in number, join with the muscle of the opposite 



side in the central point of the perineum ; the succeeding fibres, 



which arise from the pubis, are the longest, and pass backwards 



over the prostate to the side of the rectum, where they mix to a rectum, 



small extent with the fibres of the sphincter muscles, but most of 



them are continued to the tip of the coccyx (pubo-coccygem) ; and 



the posterior fibres meet the opposite muscle in a narrow apoueurosis a median 



behind the gut, and are attached in part to the side of the coccyx apon 



. . 7 . and coccyx ; 



( i sen i o - coccygeus) . 



The anterior fibres of the levator are in contact with the trian- relations of 

 gular ligament ; and there is an interval between the two muscles 

 which allows the urethra, with the vagina in the female, to pass 

 from the pelvis. The posterior border is adjacent to the coccygeus 

 muscle. The upper surface is in contact with the recto- vesical and 

 fascia ; and the under surface looks to the ischio-rectal fossa, and is 

 covered by the thiu anal fascia. 



Action. The levatores ani acting together support and raise the use, 

 floor of the pelvis, and compress the pelvic viscera. They are used fl"orf " C 

 in expelling the contents of the organs, and, in forcible expiratory on cavity of 

 efforts, they act in conjunction with the muscles of the abdominal abd 

 wall. At the end of defsecation, they empty the lower part of the or 

 rectum, compressing it from behind forwards ; and the lower fibres 

 assist in closing the anal passage. The levatores ani and coccygei 

 muscles form a fleshy layer or pelvic diaphragm across the outlet of Pelvic 

 the pelvis, similar to that which separates the abdomen from the iap ragm ' 

 chest : this partition is convex below and concave above, and gives 

 passage to the rectum. 



Dissection. The recto-vesical fascia will now be seen by Dissection 

 detaching the fibres of the levator ani and the coccygeus at their ^ r s S to " 

 origin, and throwing both downwards. The thin membrane fascia. 

 descends above the levator ani to the side of the bladder and the 

 rectum, and sends downwards sheaths round the prostate and the 

 gut. To demonstrate those sheaths, one incision is to be made 

 along the prostate, and another along the lower end of the rectum, 

 below the attachment of the fascia ; and the sheaths are to be 

 separated from the viscera. 



The RECTO-VESICAL FASCIA supports and partly invests the viscera Recto-vesi- 

 of the pelvis. Covering the pelvic surface of the levator ani, it is ^ 



fixed above, like that muscle, to the pubis in front, and to the 



obturator fascia at the side ; while behind, it is continued over the 



coccygeus muscle into the fascia of the pyriformis. Below, it meets 



the fascia of the opposite side in the centre of the pelvis, and forms forms the 



a partition across the cavity, like that of the levator ani, which is 



perforated by the bladder and the rectum. The partition is 



strengthened on each side by a thicker band (the so-called white line 



of the pelvic fascia) stretching from the pubis to the ischial spine. 



It is concave above and convex below, and divides the cavity supports 



of the pelvis from the perineal space. This septum is attached to 



the viscera which pierce it, forming ligaments for them : and from the 



under surface sheaths are prolonged on the rectum and the prostate, prolonga- 



tions are, 



