THE UKINAKY BLADDER 



1275 



before its removal from the body, it is possible to map out on its inferior aspect three 

 convex triangular areas, which may be distinguished from one another by the 

 directions in which they 'look. The three areas approach one another in the 

 region of the urethral orifice, where, in the male, a portion of the inferior aspect of 

 the bladder wall is structurally continuous with the upper part of the prostate. 

 Posterior to the urethral orifice is a triangular district, directed downwards and back- 

 wards, and related, in the male, to the seminal vesicles and the terminal portions 

 of the ductus deferentes, which, together with the recto- vesical layer of the pelvic 

 fascia, intervene in this position between the bladder and the rectum. This 

 triangular area is known as the fundus, base, or postero-inferior surface of the 

 bladder, and in the female it is directed against the anterior wall of the vagina. 

 The rest of the inferior aspect of the bladder is formed by two infero-lateral 

 areas, or surfaces, which meet in the median plane in front of the urethral orifice, 

 and are directed for the most part downwards and laterally (see Fig. 993). Each of 

 these areas extends backwards to join the fundus or postero-inferior surface, along 

 a rounded border which lies between the point where the ureter reaches the bladder 

 and the urethral orifice. The infero-lateral part of the bladder wall rests on the 

 areolar tissue covering the fascia of the leva tor ani and the obturator internus muscles, 

 and, nearer the median plane, upon the os pubis and the retro-pubic pad of fat. 



Superior surface 

 of bladder 



-Ureter 



Seminal 

 vesicle 



Lateral aspect 

 of prostate 



Urethra 



Lig. ura- Seminal 

 bilicale vesicle 

 medium 



Infero-lateral 

 area of bladder 



Lateral 

 aspect of 

 prostate 



Infero-lateral 

 area of bladder 



Urethra 



FIG. 993. THE URINARY BLADDER, PROSTATE, AND VESICULA SEMINALIS, VIEWED FROM THE LATERAL ASPECT. 



Drawn from specimens in which the viscera were hardened before removal from the body. In A the bladder 

 contained but a very small quantity of fluid ; in B the quantity was somewhat greater. In A the 

 peritoneum is shown covering the superior surface of the bladder, and its cut edge is seen where it is 

 reflected along the lateral border of the organ. In B the level of the peritoneal reflexion is indicated by 

 a dotted line. 



The three rounded borders which mark off the three triangular areas on the 

 inferior aspect of the bladder, just described, extend from the region of the urethral 

 orifice to the bladder apex, and to the points where the ureters reach the bladder 

 wall (see Figs. 991, 992). 



Shape and Relations, of the Empty Bladder. When the bladder is empty, or 

 nearly so, it has, roughly speaking, the shape of an inverted tetrahedron, whose 

 apex corresponds to the point where the urethra leaves the organ, while the base 

 of the tetrahedron is formed by the superior surface of the bladder. The three 

 basal angles of the tetrahedron correspond to the bladder apex and to the two 

 posterior angles of the bladder, or points where the ureters join the organ. The three 

 surfaces, which meet inferiorly at the urethral orifice, are only marked off from one 

 another by rounded borders, but as long as the organ is empty, or nearly so, they 

 are separated by distinct borders from the superior surface. These three areas 

 have been already described as the infero-lateral surfaces and the base of the 

 bladder (Figs. 991 and 992). Their relations have also been indicated. The 

 superior surface of the empty bladder looks upwards into the pelvic cavity ; it is 

 sonvex when the organ is contracted, concave when relaxed. This surface is covered 

 with peritoneum, and its outline, which is approximately triangular, is determined 

 by lateral and posterior borders (Fig. 993). The lateral borders of the empty 

 bladder are sharply marked, and extend from the bladder apex to the posterior angles 



