156 SPECIAL ANATOMY. 



portio spongiosa of the urethra, which it surrounds like a kind 

 of sheath, below covered by the skin of the perinaeum. The in- 

 ternal borders of the two muscles meet together. Or. : lig. perin. 

 triangular., sides of bulbus and corp. cavern, urethras, and penis. 

 Ins.: Corp. cavernosum urethras; pubo-cavernosus s. levator 

 penis, anterior portion of bulb o- caver -no sus ; sometimes appears, 

 isolated, between the lig. suspensor penis and the perinaeal mus- 

 cles. 



[The fibres of the larger portion of this muscle form a canal throiigh which 

 the bulbus corp. spong. and a portion of corp. spongiosum urethrsR pass. The 

 origin of this portion of the muscle is the tendinous layer between Corp. 

 spongiosum arid the under surface of corpora cavernosa, whence the fibres de- 

 scend, embracing the sides of the spongy body and bulb, and unite below in 

 the central line or raphe, which posteriorly consists of very condensed tissue. 

 The fibres of the smaller portion arise from the pubes by the sides of the lig. 

 suspensor penis, and, descending upon the outer borders of the crura penis, 

 from which likewise a few fibres arise, they unite in the middle line of, and 

 beneath, the corp. spongiosum urethra anterior to the fibres of the larger por- 

 tion. The posterior extremity of the muscular tube is applied to the anterior 

 surface of the deep perinseal fascia. 



Use: to compress the bulb, urethras and corp. cavernosum 

 urethras, to contract the canal of the urethra, urging forward the 

 urine or semen by jerks, or restraining their passage. 



278. 9. Constrictor cunni s. vaginas. 



Pos. : circular around the entrance into the Vagina. Or. : M. 

 sphincter ani and transv. perinsei. Ins. : Crura clitoridis (in- 

 ferior surface). Use: to contract the Vagina. [Or.: from the 

 under surface of crura clitoridis meeting below, after having em- 

 braced the sides of the vagina and nymphas.^\ 



279. 10. Constrictor urethras. 



Pos.: below lig. perinasale about the pars memb. urethras. 

 Between it and transv. perin. (profund.}, the glands of Cowper. 

 Or.: os Ischii (ram. ascendens}. Ins.: isthmus urethrse (sides). 

 Use : to compress, and shorten the membranous portion of the 

 urethra. 



280. 11. Vesicalis s. depressor vesicas. 



Pos.: at the inferior part of the urinary bladder. Or.: a. lig. 

 pubo-vesicale ; b. lig. ischio-prostaticum. Ins. : close above the 

 Prostate on the anterior and lateral surfaces of the bladder. Use : 

 to draw the bladder downwards (for example, while making water 

 in recumbent position). 



Nerves of anal and perinaeal muscles : pudend. common, and hcemorrhoid. 



