Til r. MM.I: < ; i: \ i 1 i /. ORQA* 8. 863 



transverse fibres thrown over the membranous portion of the urethra, and 



united at their e\tn niitics, which uro attached by means of apoueurotic 



<-iili, to the luteriil walls of the pelvis. Behind, the superior fibres 



i Cowper's glands, and, like the inferior, are mixed with the accelerator 



nrii 



b. Aci-f'h'ratnf Uriniv. Composed of transverse fibres encircling tho 



urethra from the ischial arch to tho free extremity of the penis, this will also 



mlied as a single organ, separated into two lateral portions by a median 



raphe passing along the whole posterior face of the urethra. The fibres pass 



from this raphe to the right and left, enter the furrow of the corpora 



; nosa, and reach the upper surface of tho urethra, where they advance 



rds each other ; they do not join ; so that tho circle formed by this 



muscle is necessarily incomplete. 



a l^-hin-Hfftltral muscle (compressor urdhrce). This is a thin fleshy 

 baud, pair, situated below and at the side of the membranous portion of the 

 urethra. Attached by some aponeurotic fibres to the ischial arch, this 

 muscle passes forward on Cowper's gland, whoso lower face it covers. At 

 the periphery of that organ, it is confounded with tho portion of Wilson's 

 muscle tli;tt envelops its upper surface. 



<1. Transeersus pertnei. This is a very thin ribbon-like fasciculus, often 



ly distinguishable from the ischio-anal muscle (lecalor ani). It 



Is transversely from the ischial tuberosity to which it is attached 



through the medium of the sacro-sciatic ligament, to the mesial line of the 



perineum, where its fibres, confounded with those of its homologue on the 



opposite side, appear to be inserted in the accelerator urinaa at its origin. 



e. Act ii in if the urethral muscles. 1. Wilson's muscle, when it contracts, 

 compresses between its two layers the membranous portion of the urethra. 

 It is a veritable sphincter, and opposes the escape of the urine ; when the 

 u is thrown from the vesiculro seminales into the urethra, it also 

 prevents that fluid entering the bladder, by permitting the accelerator to 

 empty, from before to behind, the initial dilatation of that canal. 2. The 

 is correctly named from tho part it plays in ejecting the semen 

 from the urethra, it being the chief agent in this act. 3. The ischio-urethral 

 muscle pulls back the membranous portion of the urethra, with Cowper's 

 j_'l;iiids. and, like Wilson's muscle, acts as a compressor to these. 4. The 

 trunxKeraiis perint-i dilutes the bulbous portion of the urethra, by drawing it 

 out hit' rally. 



4. VESSELS AND NI.KVKS. The urethra is supplied with blood by the 

 bullxi-urellirul arteries and the two pairs of arteries tho dorsal of the JH -ni.-: 

 Voluminous tv/Hx, frequently varicose, and satellites of the arteries, carry it 

 away. The liiwjilmlir* form a very rich plexus beneath the mucous 

 membrane; their trunks pass to the inguinal, and some to the sublumbar 

 glands. The ncrcous filaments are from the internal pudic and great 

 sympathetic. 



5. Ai OM.I-KOSES OP THE PERINEUM. In the porhie;.! r. _'i..n, the urethra 

 is covered by two superposed fibrous layers. The xnj>< r/i il njtnnfiir' .* 

 fibro-elastic, and appears to arise from tho inner surface of the thighs, 

 where it is mixed with the dartos; it covers the perineum, and its iiln..-, 



linii disassociated, disappear on the sides of the sphinet' r ani. This 



membrane is in relation, externally, with the skin, and, internally, with the 



d |> apoiieurosis. On the middle of its external face, it receives the 



ins.-rtioii of a muscular i'uM-inilus, which is detached from the sphincter. 



Tli. ./. . j, .i!..,,,,,!,-"*!*. formed of \\liitr in.-la>tie fibrous tissue, adheres to 



