URINARY BLADDER. 525 



the bladder ; but around the cervix they are collected into a thick bundle, 

 the sphincter vesicce, and are continuous before with the fibres of the pros- 

 tate. When the fibres are hypertrophied, they project into the interior of 

 the organ, forming the fasciculated bladder] ami in some bodies the mucous 

 coat may be forced outwards here and there between them, in the form of 

 sacs, producing the sacculated bladder. 



The submucous stratum (fig. 179, 3 ) forms a continuous layer over the 

 lower half of the bladder, but its fibres are scattered above. In the lower 

 third of the viscus the fibres are longitudinal, and are continued around 

 the urethra, but they become oblique above that point. At the back of 

 the bladder the layer is increased in strength by the longitudinal fibres of 

 the ureters blending with it. The projection of the uvula vesicce is due 

 to this submucous stratum. 



The muscular strata communicate freely, so that one cannot be sepa- 

 rated from another without division of the connecting bundles of fibres. 

 In both sexes the disposition of the fibres is similar (Med. Chir. Trans., 

 185G). 



Fibrous coat. A fibrous layer is placed between the muscular and 

 mucous strata, and is enumerated as one of the coats of the bladder ; it is 

 composed of areolar and elastic tissues as in other hollow viscera, in which 

 the vessels and nerves ramify. 



Dissection. The bladder is now to be opened by an incision down the 

 front ; and the cut is to be continued along the upper part of the prostate 

 gland. 



The mucous membrane of the bladder is continuous posteriorly with the 

 lining of the ureters, and anteriorly with that of the urethra. It is very 

 slightly united to the muscular layer ; and it is thrown into numerous folds 

 in the flaccid state of the viscus, except over a small triangular surface 

 behind the urethral opening. 



The membrane is of a pale rose color in the healthy state soon after 

 death. Its surface is studded with mucous follicles and branched glands, 

 particularly towards the neck of the bladder. In the epithelium covering 

 the surface are three kinds of cells : the superficial are roundish and flat- 

 tened ; the middle are pyriform ; and the deeper are conical and cylindrical. 



Objects inside the bladder. Within the bladder are the following named 

 parts, viz., the orifices of the ureters and uretlira, with the triangular sur- 

 face (fig. 179). 



Orifices. At the anterior part of the bladder is the orifice of the urethra, 

 surrounded by the prostate gland. The mucous membrane presents here 

 some longitudinal folds ; and the aperture is partly closed by a small pro- 

 minence below, uvula vesicce, occasioned by a thickening of the submucous 

 muscular and fibrous layer. This eminence is placed in front of the middle 

 lobe of the prostate ; and from its anterior part a slight ridge is continued 

 on the floor of the uretlira. 



About an inch and a half behind the orifice of the urethra, and rather 

 more than that distance apart, are the two narrow openings of the ureters 

 (fig. 181). These excretory tubes for the urine perforate the wall of the 

 bladder obliquely, lying in it for the distance of one-third of an inch, so 

 that the reflux of fluid through them towards the kidney is prevented MS 

 the bladder is distended. Each terminates by a slit-like opening in a 

 prominence formed by subjacent muscular fibres. 



Triangular surface. Immediately behind the orifice of the urethra is a 

 smooth triangular surface, which is named trigone (trigonum vesicie). Its 



