PROSTATIC PORTION SIXUS POCULARIS. 961 



brane, supported by an outer layer of submucous tissue connecting it with 

 the several parts through which it passes. In the submucous tissue there 

 are, throughout the whole extent of the urethra, two layers of plain mus- 

 cular fibres, the innermost disposed longitudinally, and the other in a 

 circular direction. In accordance with the name or character of those 

 parts through which it passes, three divisions of the urethra are separately 

 described as the prostatic, membranous, and spongy portions. 



1. The first, or prostatic portion, is the part which passes through the 

 prostate gland. It is from 12 to 15 lines in length, is the widest part 

 of the canal, and is larger in the middle than at either end : at the 

 neck of the bladder its diameter is nearly 4 lines, then it widens a little, 

 so as to be rather more than 4 lines, arid in old persons 5 or 0, after which 

 it diminishes like a funnel, until, at its anterior extremity, it is smaller 

 than at its commencement. It passes through the upper part of the pro- 

 state, 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 immediately at the neck 

 of the bladder, it is, as elsewhere stated, much more resistant. The trans- 

 verse section of the urethra, as it lies in the prostate, is widened from side 

 to Bide and somewhat folded upwards in the middle, the upper and under 

 surface being in contact. 



The lining membrane of the prostatic portion of the urethra is thrown 

 into longitudinal folds, when no fluid is passing along it ; it forms no proper 

 valve at the neck of the bladder, unless the elevation named the uvula 

 vesicse is to be regarded as such. 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 &gain 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 urethrse), more 

 generally called c,aput gallinaginis and verumontanum. On each side of this 

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

 named the prostatic sinus, the floor of which is pierced by numerous fora- 

 mina, 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 open before it. 



Sinus pocularis. 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 ejacu- 

 latory ducts, one at each side. This median depression, named sinus 

 pocularis, vesica prostatica, or utricle, 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 uterus. 



The utricle 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 prominent walls of the narrow portion form 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 tolerably thick, are composed of fibrous tissue and mucous mem- 

 brane, together with a few muscular fibres, and enclose on each side the ejacu- 

 latory duct ; numerous small glands open on its inner surface. According to 

 Kobelt and others, the caput galliiiaginis contains some well-marked erectile 



