LEVATOR AN1. COCCYGEUS. 225 



Part of the levator ani may be seen during the dissection of the 

 anal portion of the perineum by removing the fat which surrounds the 

 termination of the rectum in the ischio-rectal fossa. But, to study the 

 entire muscle, a lateral section of the pelvis must be made by sawing 

 through the pubes a little to one side of the syrnphysis, separating the 

 bones behind at the sacro-iliac symphysis, and turning down the blad- 

 der and rectum. The pelvic fascia is then to be carefully raised, be- 

 ginning at the base of the bladder and proceeding upwards, until the 

 whole extent of the muscle is exposed. 



The LEVATOR ANI is a thin plane of muscular fibres, situated on 

 each side of the pelvis. The muscle arises from the inner surface of 

 the os pubis, from the spine of the ischium, and between those points 

 from the angle of division between the obturator and the pelvic fascia. 

 Its fibres descend to be inserted into the extremity of the coccyx into 

 a fibrous raphe in front of that bone, into the lower part of the rectum, 

 base of the bladder, and prostate gland. 



In the female this muscle is inserted into the coccyx and fibrous 

 raphe, lower part of the rectum and vagina. 



Relations. By its external or perineal surface, with a thin layer of 

 fascia, by which, and by the obturator fascia, it is separated from the 

 obturator internus muscle ; with the fat in the ischio-rectal fossa, the 

 deep perineal fascia, the levator ani, and posteriorly with the gluteus 

 maximus. By its internal or pelvic surface with the pelvic fascia, 

 which separates it from the viscera of the pelvis and peritoneum. 



The COCCYGEUS MUSCLE is a tendino-muscular layer of a triangular 

 form. It arises from the spine of the ischium, and is inserted into 

 the side of the coccyx and lower part of the sacrum. 



Relations. By its internal OT pelvic surface, with the rectum ; by its 

 external surface with the lesser and greater sacro-ischiatic ligaments. 



The muscles of the perineum in the female are the same as in the 

 male, and have received analogous names. They are smaller in size, 

 and are modified to suit the different form of the organs ; they are 



Constrictor vaginae, 

 Erector clitoridis, 

 Transversus perinei, 

 Compressor urethra, 

 Sphincter ani, 

 Levator ani, 

 Coccygeus. 



The Constrictor vagina is analogous to the acceleratores urinse ; it is 

 continuous posteriorly with the sphincter ani, interlacing with its fibres, 

 and is inserted anteriorly into the sides of the corpora cavernosa, and 

 fascia of the clitoris. 



The Transversus perinei is inserted into the side of the constrictor 

 vaginas, and the levator ani into the side of the vagina. 



The other muscles are precisely similar in their attachments to those 

 in the male. 



