1904 



HUMAN ANATOMY. 



Fig. 1620. 



without rupture of the dead vesical wall is much less than that of the living organ. 

 The bladder in the female has a smaller capacity than in the male. 



The interior of the bladder varies in appearance according to the condition 

 of the mucous membrane. The latter is loosely attached to the muscular tunic 

 by submucous areolar tissue, and hence in the contracted state of the organ is thrown 

 into conspicuous, mostly longitudinal plications ; when the bladder is nlled these 

 folds are effaced and the inner surface appears smooth. With excessive distention, 

 the interlacing bundles of the muscular wall may be stretched so far apart that the 

 submucous tissue and the mucosa may occupy the interstices so formed, an irregular 

 pitting or pouching of the mucous lining resulting. A triangular area, the tj-igonum 

 vesicas, included between the urethral orifice in front and the ureteral openings behind, 

 is distinguished by its smoothness under all degrees of contraction, even in the 

 empty bladder being only indistinctly wrinkled. Over the trigone (Fig. 1620) 

 the submucosa is absent and the mucous membrane rests directly upon a compact 

 muscular stratum in which the closely placed transverse bundles of the vesical wall are 

 reinforced by radiating fibres continued from the ureteral sheath (page 1897). The 

 slightly curved posterior border or base of the trigonum is marked by a band-like 

 elevation, \.\\q plica ziretericce, or iorus uretericus of Waldeyer, that unites the open- 

 ings of the renal ducts. This ridge, best marked at its outer ends, is less evident 

 and often interrupted near the mid-line, and is subject to much individual variation. 



Its production depends upon the eleva- 

 tion of the mucosa and muscular tissue 

 in consequence of the oblique path of 

 the ureters through the vesical wall. 

 The margins of the trigonum — lateral 

 as well as posterior — are raised and its 

 central area is somewhat depressed 

 towards the zwethi-al opening . The lat- 

 ter (orificium urethrae internum) occu- 

 pies the apex of the trigonum, and is 

 usually not circular, but crescentic, 

 owing to the projection of its posterior 

 border as a small median elevation, the 

 vesical crest (uvula vesicae), that ex- 

 tends from the apical end of the trigone 

 into the urethra to become continuous 

 with the urethral crest in the prostatic 

 part of the canal. The vesical crest 

 consists of a thickening of the mucous membrane enclosing bundles of muscular 

 tissue. When hypertrophied, as it not infrequently is in aged subjects, this fold 

 may form a valvular mass that occludes the urethral orifice. The anterior wall of 

 the latter is commonly marked by low converging folds continuous with the longi- 

 tudinal plications of the urethral mucous membrane. 



The ureteral orifices are usually slit-like in form (4-5 mm. long), obliquely trans- 

 verse in direction, but may be oval, round, or punctiform (Disse). The lateral bor- 

 der of the opening is guarded by a valve-like projection (valvula ureteris) that forms 

 part of the nodular elevation that is produced by the wall of the ureter. The median 

 margin of the opening is embedded in the interureteral plica. The urethral and the 

 two ureteral openings mark the angles of an approximately equilateral triangle, the 

 sides of which, in the contracted condition of the bladder, measure from 2-2.5 cm.; 

 when the organ is expanded, this distance increases to from 3.5-5 cm. or even more. 

 The urethral orifice lies from 1.75-2. 2 cm. in front of the base of the trigone when the 

 latter is contracted. Immediately behind the vesical triangle the posterior bladder- 

 wall presents a slight depression, the retrotrigonal fossa or fovea retroureterica 

 (Waldeyer), that corresponds to the "bas-fond" of the French writers. When 

 abnormally enlarged and pouch-like, as it often is in advanced life when associated 

 with an enlarged prostate, this fossa becomes of practical importance (page 1981). 



Peritoneal Relations. — The superior surface of the empty or but slightly 

 filled bladder is completely covered by peritoneum as far as the lateral and posterior' 



Interior of lower segment of partly distended and hardened 

 bladder, viewed from above and behind. 



