BLADDER, NORMAL ANATOMY. 



385 



in health the mucous surfaces of the intestinal 

 tube and of this organ form a strong contrast, 

 more particularly if the vessels of both have 

 been injected with coloured size; the former will 

 then assume the colour of the injection, the lat- 

 ter will continue pale, although numerous ves- 

 sels become apparent in the submucous tissue. 

 The mucous lining of the bladder in the healthy 

 state does not present any distinct follicles or 

 cryptae except near the cervix, which become 

 very distinct in chronic disease. A cuticular or 

 epiderrnoid covering cannot be detected in 

 health, although in certain states of disease a 

 substance very similar to cuticle is occasionally 

 discharged in shreds and flakes. When the blad- 

 der is empty and contracted, the mucous mem- 

 brane is thrown into numerous ruga?, existing 

 chiefly in a transverse direction, which are most 

 distinct if a very recently contracted bladder be 

 examined. When the organ is distended, these 

 ruga' disappear, so that their existence may be 

 considered as evincing a want of elasticity in 

 this tissue. This membrane presents some pecu- 

 liarities throughout the extent of a small region 

 named the ' trigone ' or the 'velum' of the 

 bladder : this term is applied to a small triangular 

 space, nearly equilateral, situated about the 

 middle of the inferior region, and leading to the 

 neck of the bladder. The base of this space is a 

 lunated line leading from the orifice of one 

 ureter to the other ; the sides are marked by 

 lines which converge forwards from these open- 

 ings to a slight projection at the neck of the blad- 

 der named the ' uvula,' which is immediately 

 behind or rather in the orifice of the urethra. 

 Throughout the area of this space the mucous 

 membrane is very smooth and free from rugre 

 or folds, as it adheres closely to the fibrous or 

 compact cellular substance beneath : it is also 

 more vascular, being generally of a delicate rose 

 colour, or variegated with fine vessels, and when 

 minutely examined with a magnifying lens 

 numerous fine villi can be discerned. On the 

 whole this surface appears to be delicately and 

 peculiarly organized, and no doubt possesses 

 Higher sensibility than the remainder of the in- 

 ternal surface of the organ. The posterior part 

 of the trigone is thinner than the anterior ; the 

 line which marks its base is a thickened band of 

 the circular or transverse muscular fibres,behind 

 which the inferior fundus of the bladder is fre- 

 quently dilated into a pouch which presses 

 against the rectum, and where a calculus some- 

 times rests, so as to elude the search of the 

 sound unless the finger be introduced into the 

 rectum : in old persons this pouch sometimes 

 remains constantly full of urine, the muscular 

 coat of the bladder not being able to contract 

 it. The lines which form the sides of the tri- 

 gone, and which extend from the orifices of 

 each ureter to the uvula, are composed of a 

 slight projection of the mucous membrane, be- 

 neath which is some cellular tissue, and in 

 some cases a few pale muscular fibres are dis- 

 tinctly seen. These lateral lines are not in 

 general very distinct, at least in the healthy 

 bladder; their distinctness is owing to little 

 more than being the borders of this space. In 



VOL. I. 



some cases, particularly when the prostate has 

 been enlarged or the urethra obstructed, they 

 are found very distinct, the muscular fibres 

 they contain being thickened even in a greater 

 degree than the other portions of the muscular 

 coat of the bladder. These lateral fasciculi 

 appear to be little more than some of the lon- 

 gitudinal muscular fibres of the bladder con- 

 verging towards its cervix. Sir C. Bell, 

 however, has attached a particular importance 

 to these muscles, which he denominates the 

 " muscles of the ureters :" his description of 

 their attachments and use is as follows, in his 

 own words : " The use of these muscles is to 

 assist in the contraction of the bladder, and at 

 the same time to close and support the mouths 

 of the ureters." " They guard the orifices of 

 the ureters by preserving the obliquity of the 

 passage, and by pulling down the extremities of 

 the ureters according to the degree of the con- 

 traction of the bladder generally."* 



It appears very questionable how far this 

 statement as to the structure of these lines is 

 generally correct, and it is still farther doubtful 

 whether the use assigned is correctly ascribed 

 or not ; for it may be remarked that these lines 

 are often very faintly traced, that the muscular 

 structure within them is sometimes very in- 

 distinct, that in females it is scarcely observable, 

 in very young children also of either sex it is 

 not well developed ; whereas if such an import- 

 ant office as that of guarding the ureters de- 

 pended on these muscular fibres, it is most 

 probable, and indeed is even certain that their 

 presence would be constant and their deve- 

 lopment more uniform. Again, the fact of the 

 dead bladder when fully distended with fluid, or 

 even with air when the urethra is tied, and the 

 contents not escaping through the ureters, is a 

 strong proof that the oblique or valvular direc- 

 tion of the latter is the true cause of the non- 

 regurgitation, and that it does not depend on 

 the contraction of any particular muscular 

 fibres. Again too, in animals this structure, as 

 described by Sir C. Bell, is not at all obvious 

 although the ureters have the same oblique 

 course as in man ; it would rather appear that 

 these muscular bands, which are occasionally 

 very distinct along the sides of the trigone, are 

 only portions of the longitudinal fibres, and 

 that their action will be to shorten the trigone, 

 to draw its base forward, and thus to assist in 

 emptying the bladder. They may doubtless assist 

 in fixing the orifice of the ureters and moving 

 these in proportion as the surrounding parts are 

 affected, but the opinion that the preservation 

 of the valvular or oblique course is depending 

 upon them appears to be invalidated by the fore- 

 going remarks, as well as by the following expe- 

 riment. The healthy bladder of an adult male, 

 recently dead, was opened to a small extent on 

 its fore-part, and the sides of the trigone were 

 cut by a sharp-pointed bistoury passed beneath 

 each of them; the urethra was then lif'd,and the 

 bladder carefully closed : its cavity was next 

 fully distended witii water, and the fluid was 



* Meclico-Chir. Trans, vol. iii. p. 178. 



2 c 



