THE PERINEUM, MALE. 397 



THE PERINEUM, Male. 



The perineum is a diamond-shaped space corresponding 

 to the boundaries of the pelvic outlet. 



The pelvic outlet is formed by the lower borders of the 

 ossa innominata joined in front at the symphysis and be- 

 hind by the wedge-shaped sacrum. 



LANDMARKS. 



The borders of the perineal space can be felt, and are 

 formed by the under surface of the pubic arch, in front ; 

 the rami of the pubes and ischium, and the tuberosities of 

 the latter, at the side anteriorly ; the lower border of the 

 gluteus maximus, beneath which can be outlined the great 

 sacrosciatic ligaments, at the side posteriorly ; and the tip 

 of the coccyx in the posterior median line. 



In the median line, in front of the coccyx, is the anus, 

 and in front of the anus reaching up to the base of the 

 scrotum is the bulb of the penis. 



Laterally, in the anterior part of the perineum, the crura 

 of the penis will be felt covering the ischiopubic rami ; 

 and posteriorly, at the side of the anus, is a depression 

 filled with fat the ischiorectal fossa. 



The perineum is divided by a transverse line from the 

 tuberosities of the ischium into the anterior compartment, 

 or the perineum proper, and the posterior division, or the 

 ischiorectal fossae. 



In order to understand the construction of the pelvic 

 floor it will be well to first study the arrangement of the 

 fasciae which assist in closing the pelvic outlet and support 

 the pelvic viscera in position. Start from the interior of 

 the pelvis. Attached to the inner surface of the obturator 

 membrane and the margin of the bone adjacent thereto, 



