846 SURGICAL ANATOMY OF THE PERINEUM. 



with the prostate gland, descending by its side and surrounding it as in a sling, 

 it has been described by Santorini and others as a distinct muscle, under the 

 name of the Levator Prostatse. In the female, the anterior fibres of the Levator 

 Ani descend upon the sides of the vagina. 



Relations. By its upper or pelvic surface with the recto- vesical fascia, which 

 separates it from the viscera of the pelvis and from the peritoneum. By its 

 outer ^ or perineal surface, it forms the inner boundary of the ischio-rectal fossa, 

 and is covered by & quantity of fat, and by a thin layer of fascia continued from 

 the obturator fascia. Its posterior border is continuous with the Coccygeus mus- 

 cle. Its anterior border is separated from the muscle of the opposite side by a 

 triangular space, through which the urethra and, in the female, the vagina 

 pass from the pelvis. 



Actions. This muscle supports the lower end of the rectum and vagina, and 

 also the bladder during the efforts of expulsion. 



The Coccygeus is situated behind and parallel with the preceding. It is a 

 triangular plane of muscular and tendinous fibres, arising, by its apex, from 

 the spine of the ischium and lesser sacro-sciatic ligament, and inserted, by its 

 base, into the margin of the coccyx and into the side of the lower piece of the 

 sacrum. This muscle is continuous with the posterior border of the Levator 

 Ani, and closes in the back part of the outlet of the pelvis. 



Relations. By its inner or pelvic surface, with the rectum. By its external 

 surface, with the lesser sacro-sciatic ligament. By its posterior border, with the 

 Pyriformis. 



Action. The Coccygei muscles raise .and support the coccyx, after it has been 

 pressed backwards during defecation or parturition. 



Position of the Viscera at the Outlet of the Pelvis. Divide the central tendinous point of the 

 perineum, separate the rectum from its connections by dividing the fibres of the Levator Ani, 

 which descend upon the sides of the prostate gland, and draw the gut backwards towards the 

 coccyx, when the under surface of the prostate gland, the neck and base of the bladder, the 

 vesiculae seminales, and vasa deferentia will be exposed. 



The Prostate Gland is placed immediately in front of the neck of the bladder, 

 around the prostatic portion of the urethra, its base being turned backwards, 

 and its under surface towards the rectum. It is retained in its position by the 

 Levator Prostatas and by the pubo-prostatic ligaments, and is invested by a dense 

 fibrous covering, continued from the posterior layer of the deep perineal fascia. 

 The longest diameters of this gland are in the antero-posterior direction, and 

 transversely at its base; and hence the greatest extent of incision that can be 

 made in it without dividing its substance completely across, is obliquely out- 

 wards and backwards. This is the direction in which the incision is inade 

 through it in the operation of lithotomy, the extent of which should seldom 

 exceed an inch in length. The relations of the prostate to the rectum should 

 be noticed ; by means of the finger introduced into the gut, the surgeon detects 

 enlargement or other disease of this organ ; he is enabled also, by the same means, 

 to direct the point of a catheter when its introduction is attended wtth much 

 difficulty, either from injury or disease of the membranous or prostatic portions 

 of the urethra. 



Behind the prostate is the posterior surface of the neck and base of the blad- 

 der ; a small triangular portion of this organ is seen, bounded, in front by the 

 prostate gland ; behind, by the recto-vesical fold of the peritoneum ; on either 

 side, by the vesiculae seminales and vasa deferentia ; and separated from direct 

 contact with the rectum by the recto-vesical fascia. The relation of this por- 

 tion of the bladder to the rectum is of extreme interest to the surgeon. In 

 cases of retention of urine, this portion of the organ is found projecting into 

 the rectum, between three and four inches from the margin of the anus, and 

 may be easily perforated during life without injury to any important parts; this 

 portion of the bladder is, consequently, frequently selected for the performance 

 of the operation of tapping the bladder. If the finger is introduced into the 

 bowel, the surgeon may, in some cases, learn the position, as well as the size 



