INTERIOR OF THE PELVIS. 211 



to the side of the bladder and rectum. Between these two 

 la}'ers is the levator ani muscle. 



The LEVATOR ANI MUSCLE, a broad, thin plane of mus- 

 cular fibres, forming, with its fellow, the floor of the pelvis, 

 is compared by Bell to a pair of hands which dip down to 

 hold up and support the viscera, the simile being suggested 

 by the funnel-shaped manner in which they embrace the 

 pelvic contents. The muscle arises from the inner surface 

 of the os pubis, from the tendinous line constituting the 

 >int of separation between the obturator and recto-vesical 

 iscia, and from the spine of the ischium ; it is inserted 

 ito the lower part of the rectum, where its fibres become 

 mnected and continuous with those of the internal 

 )hincter, and into the base of the bladder and the pros- 

 ite. In the female, the levator ani is inserted into the 

 ide of the vagina as well as the rectum. 



The two following muscles are very difficult of demonstration, 

 hey are to be sought for between the two layers of the triangular 

 igament, where they lie connected with the membranous urethra and 

 ibic bones. 



The COMPRESSOR URETHRA, or GUTHRIE'S MUSCLE, con- 

 sists of two transverse layers of muscular fibres, attached 



y a narrow origin on each side to the ramus of the pubes; 



icy expand at their central portion, one above and the 

 >ther below the urethra, and are inserted into a fibrous 



iphe on the median line, extending the whole length of the 



lembranous urethra. 



WILSON'S MUSCLE is considered, when present, as a part 

 >f the preceding, and as being merely another attachment 

 )f its fibres. It arises, tendinous, from the under part of 

 the symphysis of the pubes, and descends, fan-shaped, to 

 be inserted into the upper layer of the compressor urethne 

 on the median line. 



The pelvic viscera should now be removed, and in such a way as 

 to leave the internal muscles and nerves of the pelvis uninjured ; the 

 arterial connections must be divided, and the rectum dissected up 

 from the concavity of the sacrum. The penis should be removed 

 with the viscera, detaching it from the arch of the pubes, by carrying 

 the knife close to the bone. In the female, the vulva and anus should 

 be included in an elliptical incision, and carefully dissected away 

 from the raini of the ischia and pubes. These parts should be laid 

 aside for further examination. 



Within the pelvis will be noticed the bellies and origins 



