1922 HUMAN ANATOMY. 



(there is no distinct linea alba at this point), and prevesical fatty connective tissue 

 in the space of Retzius. Sometimes this fat can be gently pushed or sponged 

 upward and carries the peritoneum with it. The method of securing a non-peritoneal 

 area of bladder and abdominal wall for this operation (as for others involving a 

 suprapubic cystotomy) has been sufficiently described. 



T\\Q feviale bladder is less capacious than the male bladder. Its longest diame- 

 ter is transverse, as posteriorly the pelvic space is occupied by the uterus and 

 vagina, and as the female pelvis is relatively wider than that of the male. 



The lesser depth of the pubic symphysis in the female and the absence of the 

 prostate result in a relatively lower vesical outlet and a short, direct, distensible 

 urethra, the dilatability of which (also on account of the absence of the prostate) 

 extends to and includes the vesical neck. 



As these conditions favor easy and full evacuation of the bladder, cystitis and 

 stone are comparatively uncommon ; and as they facilitate intravesical exploration 

 or operation per urethram, cystotomy in the female is rarely called for. Foreign 

 bodies introduced by the urethra are relatively common in the female bladder. 



The utero-vesical pouch of peritoneum does not descend so low as the recto- 

 vesical pouch in the male. Below it the close relations between the bladder and the 

 cervix uteri and the upper half of the vagina lead to the involvement of the bladder 

 in many of the diseases originating in these structures. The latter relation permits 

 of the recognition by vaginal touch of calculi impacted in the lower ends of the 

 ureters, the orifices of which are about opposite the middle of the vagina. 



THE URETHRA. 



The urethra — the canal conveying the urine from the bladder to the exterior of 

 the body — differs in the two sexes, since in the male, in addition to its primary com- 

 mon function of conducting the urine, it serves for the escape of the secretions of the 

 testicles, seminal vesicles, prostate, Cowper's glands, and urethral glands. It is of 

 interest to note that in the lowest mammals, the monotremes, in which the urethra and 

 intestine open into a common space, the cloaca, the seminal duct is prolonged to the 

 end of the penis as a separate canal. Embryologically the male urethra consists of 

 two parts, 3. posterior segment — homologous with the canal in the female — beginning 

 at the bladder and ending at the openings of the ejaculatory ducts, and an anterior 

 segment including the remainder of the canal. With regard to the regions of the 

 body in which they lie, the urethra may be considered as being composed of a pel- 

 vic^ a perineal, and a penile portion. It is more usual, however, to describe the 

 male urethra as consisting of the prostatic, membranous, and spongy portions, — a 

 division based upon more or less definite anatomical relations of structures through 

 which it passes. 



The prostatic portion (pars prostatica), from 2-3 cm. (^-i^ in.) in length, 

 descends with a slight curve, but almost vertically, from the internal urethral orifice 

 of the urethra to the superior layer of the triangular ligament. Beyond the vesical 

 wall, which embraces its commencement {pars intramuralis of Waldeyer), it is en- 

 tirely surrounded by the prostate, \yhich it pierces from base to apex (Fig. 1619). 

 Notwithstanding, this part of the urethra admits of considerable dilatation, although 

 ordinarily its lumen is more or less obliterated by the apposition of the anterior and 

 posterior walls. At the two ends of this division the lumen is narrower than in the 

 intervening part, although this spindle-form dilatation is reduced by the encroach- 

 ment of a fusiform elevation, the urethral crest (crista urethralis) or verumontanum, 

 that extends along the dorsal w^all from the ridge (iizmla) on the vesical trigone above 

 to the membranous urethra below, into the folds of w^hich it fades, usually by diverging 

 ridges (frenula cristae urethralis). On transverse section (Fig. 1681), the lumen of 

 this part of the urethra appears crescentic in outline in consequence of the projection 

 of the crest. The most prominent and expanded part of the latter rcolliculus semi- 

 nalis) is occupied by the slit-like opening of ihe prostatic utricle (utriculus prostaticus) 

 or sinus pocularis, a tubular diverticulum, usually from 6-8 mm. in length, but some- 

 times much longer, that leads upward and backward into the substance of the pros- 

 tate and represents the fused lower ends of the Miillerian ducts of the embryo ; the 



