433 THE MALE URETHRA. 



farther ou it diminishes like a funnel, until, at its anterior limit, it 

 is smaller than at its commencement. It passes through the upper part 

 of the prostate, above the middle lobe, so that there is more of the gland 

 below it than above. Though enclosed in the firm glandular substance, 

 it is more dilatable than any other part of the urethra ; but imme- 

 diately at the neck of the bladder, it is, as elsev*'here stated, mucli 

 more resistant. The transverse section of the uretlira, as it lies in the 

 prostate, is widened from side to side and curved with the convexity 

 upwards, the upper and under mucous surfaces being in contact. 



The lining membrane of the prostatic portion of tlie urethra is 

 thrown into longitudinal folds, when not distended by fluid. Towards 

 the neck of the bladder, a slight elevation on the lower surface passes 

 back into the uvula vesicse. Somewhat in advance of this, and con- 

 tinued from it along the floor of the passage, projects a narrow 

 median ridge, about 8 or 9 lines in length, and 1-^ line in its greatest 

 height ; this ridge gradually rises into a peak, and sinks down again 

 at its anterior or lower end, and is formed by an elevation of the 

 mucous membrane and subjacent tissue. This is the crest of the 

 urethra (crista urethra3), which also receives the names of collicuhis 

 seminalis, caput gallinaginis and vcrumontanum. On each side of this 

 ridge the surface is slightly depressed, so as to form a longitudinal 

 groove, named the prostatic, sinas, the floor of which is pierced by nu- 

 merous foramina, the orifices of the prostatic ducts. Through these a 

 viscid fluid oozes out on pressure ; the ducts of the middle lobe open 

 behind the urethral crest, and some others o])en before it. The prostatic 

 urethral mucous membrane is covered by a flat laminated epithelium. 



Vesicnla j^rostafica. — At the fore part of the most elevated portion of 

 the crest, and exactly in the middle line, is a recess, upon or within 

 the margins of which are placed the slit-like openings of the common 

 seminal or ejaculatory ducts, one at each side. This median depression 

 leads into the prostatic vesicle, which has been named also sinns pocii- 

 laris, or iitrkle. It was first described by Morgagni, and has more 

 lately attracted renewed attention, as corresponding with the structure 

 which in the female is developed into the uterine passage. 



The vesicle forms a cul-de-sac running upwards or backwards, from 

 three to five lines deep, and usually about one line wide at its entrance 

 and for some distance up, but acquiring a width of at least two lines at 

 its upper end or fundus. The narrow portion runs in the urethral crest, 

 and its fundus appears to lie behind and beneath the middle lobe, and 

 between the two lateral lobes of the prostate. Its parietes, which are dis- 

 tinct, and of some thickness, are composed of fibrous tissue and mucous 

 membrane, together with a few muscular fibres, and enclose on each side 

 the ejaculatory duct ; numerous small ramified and convoluted glands 

 open on its inner surface. The epithelial lining is of the flat laminated 

 kind. According to Kobelt and others, the caput gallinaginis contains 

 some well-marked erectile and plain muscular tissue, and it has been 

 supposed that this eminence, when distended with blood, may offer an 

 obstacle to the passage of the semen backwards into the bladder. (E. 

 H. Weber, Zusatze zur Lehre vom Baue und Verrichtungeu der Gesch- 

 lechts-Organe, 1846; Huschke in Soemmerring's Anatomie, vol.v. ; 

 Leuckart, " Vesicnla Prostatica," in Cyclop, of Anat. & Phys.) 



2. The membranous portion of the urethra comprises the part 

 between the apex of the prostate and the bulb of the corpus spongio- 



