BLADDER, NORMAL ANATOMY. 385 



in health the mucous surfaces of the intestinal some cases, particularly when the prostate has 

 tube and of this organ form a strong contrast, been enlarged or the urethra obstructed, they 

 more particularly if the vessels of loth have are found very distinct, the muscular fibres 

 been injected with coloured size; the former will they contain being thickened even in a greater 

 then assume the colour of the injection, thelat- degree than the other portions of the muscular 

 ter will continue pale, although numerous ves- coat of the bladder. These lateral fasciculi 

 sels become apparent in the submucous tissue, appear to be little more than some of the lon- 

 The mucous lining of the bladder in the healthy gitudinal muscular fibres of the bladder con- 

 state does not present any distinct follicles or verging towards its cervix. Sir C. Bell, 

 cryptae except near the cervix, which become however, has attached a particular importance 

 very distinct in chronic disease. A cuticular or to these muscles, which he denominates the 

 epidermoid covering cannot be detected in " muscles of the ureters :" his description of 

 health, although in certain states of disease a their attachments and use is as follows, in his 

 substance very similar to cuticle is occasionally own words : " The use of these muscles is to 

 discharged in shreds and flakes. When the blad- assist in the contraction of the bladder, and at 

 der is empty and contracted, the mucous mem- the same time to close and support the mouths 

 brane is thrown into numerous rugae, existing of the ureters." " They guard the orifices of 

 chiefly in a transverse direction, which are most the ureters by preserving the obliquity of the 

 distinct if a very recently contracted bladder be passage, and by pulling down the extremities of 

 examined. When the organ is distended, these the ureters according to the degree of the con- 

 rugae disappear, so that their existence may be traction of the bladder generally."* 

 considered as evincing a want of elasticity in It appears very questionable how far this 

 this tissue. This membrane presents some pecu- statement as to the structure of these lines is 

 liarities throughout the extent of a small region generally correct, and it is still farther doubtful 

 named the ' trigone' or the ' velum' of the whether the use assigned is correctly ascribed 

 bladder : this term is applied to a small triangular or not ; for it may be remarked that these lines 

 space, nearly equilateral, situated about the ar e often very faintly traced, that the muscular 

 middle of the inferior region, and leading to the structure within them is sometimes very in- 

 neck of the bladder. The base of this space is a distinct, that in females it is scarcely observable, 

 lunated line 'leading from the orifice of one in very young children also of either sex it is 

 ureter to the other; the sides are marked by not well developed ; whereas if such an import- 

 lines which converge forwards from these open- ant office as that of guarding the ureters de- 

 ings to a slight projection at the neck of the blad- pended on these muscular fibres, it is most 

 der named the ' uvula,' which is immediately probable, and indeed is even certain that their 

 behind or rather in the orifice of the urethra, presence would be constant and their deve- 

 Throughout the area of this space the mucous lopment more uniform. Again, the fact of the 

 membrane is very smooth and free from rugae dead bladder when fully distended with fluid, or 

 or folds, as it adheres closely to the fibrous or even with air when the urethra is tied, and the 

 compact cellular substance beneath : it is also contents not escaping through the ureters, is a 

 more vascular, being generally of a delicate rose strong proof that the oblique or valvular direc- 

 colour, or variegated with fine vessels, and when tion of the latter is the true cause of the non- 

 minutely examined with a magnifying lens regurgitation, and that it does not depend on 

 numerous fine villi can be discerned. On the the contraction of any particular muscular 

 whole this surface appears to be delicately and fibres. Again too, in animals this structure, as 

 peculiarly organized, and no doubt possesses described by Sir C. Bell, is not at all obvious 

 higher sensibility than the remainder of the in- although the ureters have the same oblique 

 ternal surface of the organ. The posterior part course as in man ; it would rather appear that 

 of the trigone is thinner than the anterior ; the these muscular bands, which are occasionally 

 line which marks its base is a thickened band of very distinct along the sides of the trigone, are 

 the circular or transverse muscular fibres, behind only portions of the longitudinal fibres, and 

 which the inferior fundus of the bladder is fre- that their action will be to shorten the trigone, 

 quently dilated into a pouch which presses to draw its base forward, and thus to assist in 

 against the rectum, and where a calculus some- emptyingthe bladder. They may doubtless assist 

 times rests, so as to elude the search of the in fixing the orifice of the ureters and moving 

 sound unless the finger be introduced into the these in proportion as the surrounding parts ar 

 rectum : in old persons this pouch sometimes affected, but the opinion that the preservation 

 remains constantly full of urine, the muscular of the valvular or oblique course is depending 

 coat of the bladder not being able to contract upon them appears to be invalidated by the fore- 

 it. The lines which form the sides of the tri- going remarks, as well as by the following exps- 

 gone, and which extend from the orifices of riment. The healthy bladder of an adult male, 

 each ureter to the uvula, are composed of a recently dead, was opened to a small extent on 

 slight projection of the mucous membrane, be- its fore-part, and the sides of the trigone were 

 neath which is some cellular tissue, and in cut by a sharp-pointed bistoury passed beneath 

 some cases a few pale muscular fibres are dis- each of them ; the urethra was then tied, and the 

 tinctly seen. These lateral lines are not in bladder carefully closed : its cavity was next 

 general very distinct, at least in the healthy fully distended with water, and the fluid wa? 

 bladder; their distinctness is owing to little 



more than being the borders of this space. In * Medico-Chir. Trans, vol. iii. p. 178. 



VOL. i. 2 c 



