534 PROSTATE GLAND. 



originating at the terminations of the ureters, and converging to the neck 

 of the bladder : the existence of these muscles is not well established 

 The fibres corresponding with the trigonum vesicse are transverse. 



It has been shown by Mr. Guthrie,* that there are no fibres at the neck 

 of the bladder capable of forming a sphincter vesicse ; but Mr. Lanef has 

 described a fasciculus of muscular fibres which surround the commence- 

 ment of the urethra, and perform such an office. These fibres form a 

 narrow bundle above the urethra, but spread out below behind the prostate 

 gland : they are brought into view by dissecting off the mucous mem- 

 brane from around the orifice of the urethra. 



Sir Astley Cooper has described around the urethra, within the prostate 

 gland, a ring of elastic tissue, or, rather, according to Mr. Lane, of mus- 

 cular fibres, which has for its object the closure of the urethra against the 

 involuntary passage of the urine. It is into this ring that the longitudinal 

 fibres of the detrusor urinse are inserted, so that the muscle, taking a fixed 

 point at the os pubis, will not only compress the bladder, and thereby 

 tend to force its contents along the urethra, but will at the same time, by 

 means of its attachment to the ring, dilate the entrance of the urethra, and 

 afford a free egress to the contents of the bladder. 



The Mucous coat is thin and smooth, and exactly moulded upon the 

 muscular coat, to which it is connected by a somewhat thick layer of sub- 

 mucous tissue, called by some anatomists the nervous coat ; its papilla 

 are very minute, and there is scarcely a trace of mucous follicles. This 

 mucous membrane is continuous, through the ureters, with the lining 

 membrane of the uriniferous ducts, and, through the urethra, with that of 

 the prostatic ducts, tubuli seminiferi, and Cowper's glands. 



Upon the internal surface of the base of the bladder is a triangular 

 smooth plane, of a paler colour than the rest of the mucous membrane, the 

 trigonum vesicse, or trigone vesicate, (fig. 237.) This is the most sensi- 

 tive part of the bladder, and the pressure of calculi upon it gives rise to 

 great suffering. It is bounded on each side by the raised ridge, corre- 

 sponding with the muscles of the ureters, at each posterior angle by the 

 openings of the ureters, and, in front, by a slight elevation of the mucous 

 membrane at the entrance of the urethra, called uvula vesicce. 



The external surface of the base of the bladder corresponding with the 

 trigonum, is also triangular, and is separated from the rectum merely by a 

 thin layer of fibrous membrane, the recto-vesical fascia. It is bounded 

 behind by the recto-vesical fold of peritoneum ; and on each side by the 

 vas deferens and vesicula seminalis, which converge almost to a point at 

 the base of the prostate gland. It is through this space that the opening 

 is made in the recto-vesical operation for puncture of the bladder. 



PROSTATE GLAND. 



The prostate gland (T^otrfrijfM prseponere) is situated in front of the neck 

 of the bladder, behind the deep perineal fascia, and upon the rectum, 

 through which latter it may be felt with the finger. It surrounds the com- 

 mencement of the urethra for a little more than an inch of its extent, and 

 resembles a Spanish chestnut both in size and form ; the base being 

 directed backwards towards the neck of the bladder, the apex forwards, 



* On the Anatomy and Diseases of the Neck of the Bladder and of the Urethra." 

 f Lancet, vd. i. 1842-43, p. 070. 



