terior fibers unite with the under surface of the triangular 

 ligament. 



The above three muscles and enclosed triangular space are 

 between the superficial and the deep perineal fasciae, i. e., 

 below the lower layer of the triangular ligament. 



The constrictor, or compressor urince, rises from the ischio- 

 pubic rami, from the two layers of the triangular ligament, 

 between which it is placed, and surrounds the membranous 

 portion of the urethra, forming a kind of sphincter. A median 

 raphe sometimes divides the muscle. Its hindermost fibers 

 have been described as the transversus perinei profundus. 



Most of the fibers pass transversely, others obliquely, others 

 circularly around the urethra, and on the inferior surface is 

 a longitudinal slip from the base to the apex of the triangular 

 ligament. 



Nerves. External sphincter by the fourth sacral and inferior 

 hemorrhoidal of the pudic, levator ani by the fourth sacral 

 and perineal branch of the pudic; coccygeus by the fourth 

 sacral; the three superficial genitourinary muscles by the 

 perineal branch of the pudic; constrictor urethrse by the dorsal 

 nerve of the penis. 



Actions. Internal sphincter wholly involuntary, external 

 usually involuntary, but made firmer by act of the will; the 

 levator ani and coccygeus support and raise the floor of the 

 pelvis, and thus have to do with forced expiration; the levator 

 also assists in emptying the lower rectum, raising and expand- 

 ing its aperture, but some of its fibers act with the external 

 sphincter in closing the anus; the transversi fix the "central 

 point" and give support to the ejaculator muscles; the ischio- 

 cavernosi compress the crus and help produce and maintain 

 erection of the penis; the bulbocavernosi forcibly eject fluid 

 mostly voluntarily at the end of micturition, involuntarily in 

 the emission of semen; they also are supposed to aid erection 

 of the penis; the constrictor urethra; assists the bulbocavernosi 

 in clearing the urethra and erects penis. (Henle). 



In the female, the //v///,v/r/vw,v perinei, external sphincter, 

 levator ani, erector clitoridis (ischiocavernosus) correspond 

 13 



