786 PELYIC FASCIA. 



to the "brim of the pelvis for a short distance at the side of this cavity, and to the 

 inner surface of the bone round the attachment of the Obturator internus. At 

 the posterior border of this muscle, it is continued backwards as a very thin 

 membrane in front of the Pyriformis muscle and sacral nerves, behind the branches 

 of the internal iliac artery and vein which perforate it, to the front of the sacrum. 

 In front, it follows the attachment of the Obturator internus to the bone, arches 

 beneath the obturator vessels, completing the orifice of the obturator canal, and 

 at the front of the pelvis is attached to the lower part of the symphysis pubis ; 

 being continuous below the pubes with the fascia of the opposite side so as to 

 close the front part of the outlet of the pelvis, blending with the posterior layer 

 of the triangular ligament. At the level of a line extending from the lower 

 part of the symphysis pubis to the spine of the ischium, is a thickened whitish 

 band ; this marks the attachment of the Levator ani muscle to the pelvic fascia, 

 and corresponds to its point of division into two layers, the obturator and recto- 

 vesical. 



The obturator fascia descends and covers the Obturator internus muscle. It is 

 a direct continuation of the pelvic fascia below the white line above mentioned, 

 and is attached to the pubic arch and to the margin of the great sacro-sciatic 

 ligament. This fascia forms a canal for the pudic vessels and nerve in their 

 passage forwards to the perineum, and is continuous with a thin membrane which 

 covers the perinoal aspect of the Levator ani muscle, called the ischio-rectal or anal 

 fascia. 



The recto-vesical fascia (visceral layer of the pelvic fascia) descends into the 

 pelvis upon the upper surface of the Levator ani muscle, and invests the prostate, 

 bladder, and rectum. From the inner surface of the symphysis pubis a short 

 rounded band is continued to the upper surface of the prostate and neck of the 

 bladder, forming the pubo-prostatic or anterior true ligaments of the bladder. At 

 the side, this fascia is connected to the side of the prostate, inclosing this gland 

 and the vesical prostatic plexus, and is continued upwards on the surface of the 

 bladder, forming the lateral true ligaments of the organ. Another prolongation 

 invests the vesiculas seminales, and passes across between the bladder and rectum, 

 being continuous with the same fascia of the opposite side. Another thin pro- 

 longation is reflected round the surface of the lower end of the rectum. The 

 Levator ani muscle arises from the point of division of the pelvic fascia ; the 

 visceral layer descending upon and being intimately adherent to the upper surface 

 of this muscle, while the under surface is covered by a thin layer derived from 

 the obturator fascia, called the ischio-rectal or anal fascia. In the female, the 

 vagina perforates the recto-vesical fascia, and receives a prolongation from it. 



