BLADDER. Ool 



bands of oblique fibres are described by Sir Charles Bell, as origi- 

 ginating at the terminations of the ureters, and converging to the 

 neck of the bladder ; the existence of these muscles is not well es- 

 tablished. 



It has been well shown by Mr. Guthrie,* that there are no fibres 

 at the neck of the bladder capable of forming a sphincter vesicre. 

 The fibres corresponding with the trigonum vesicas are transverse. 



Sir Astley Cooper has demonstrated around the neck of the bladder 

 within the prostate gland, a ring of elastic tissue, which has for its 

 object the mechanical closure of the urethra against the involuntary 

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

 fibres of the detrusor urina? are inserted, so that this 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 this ring dilate the en- 

 trance of the urethra, and afford a free egress to the contents of the 

 bladder.f 



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



t In Horner's Special Anatomy, vol. ii. p. 82, we find a different account of the 

 sphincter apparatus at the neck of the bladder, which I subjoin because I have found 

 it correct in every case which I have examined. On one point I beg leave to differ 

 from Prof. Horner's description, viz. : in place of considering the transverse band con- 

 necting- the two lobes of the prostate, and the triangular lamina underlying the vcsical 

 triangle as muscular, I believe them to belong to the proper elastic tissue such as forms 

 the ligamentum nuchse in the mammiferse and the middle coat of the arterial system. 

 I annex a cut to the description of Horner, taken by his permission from a drawing 

 by Peale. G. 



" The internal orifice of the neck of 

 the bladder resembles strongly that of a 

 Florence flask, modified, however, by 

 the projection of the uvula vesicoe, which 

 makes it somewhat crescentic below. 

 The neck of the bladder penetrates the 

 prostate gland, but, at its commence- 

 ment, is surrounded by loose cellular 

 tissue containing a very large and abun- 

 dant plexus of veins. The internal layer 

 of muscular fibres is here transverse ; 

 and they cross and intermix with each 

 other in different directions, forming a 

 close compact tissue, which has the 

 effect of a particular apparatus for re- 

 taining the urine, and is called muscu- 

 lus sphincter vesicee urfnariae. Gene- 

 rally, anatomists have not considered 

 this structure as distinct from the mus- 

 cular coat at large ; but Sir Charles Bell, 

 now a professor in the University of 

 Edinburgh, whose reputation as an ana- 

 tomist is well established, gives the fol- 

 lowing account of it : 



" ' Begin the dissection by taking oft" 

 the inner membrane of the bladder from 

 around the orifice of the urethra. A set 

 of fibres will be discovered, on the lower 



t Represents the neck of the bladder with the sphincter apparatus as described by 

 Horner. 1, 1. Orifice of the neck of the bladder. '2, 2, 2, 2. Orifices of the ureters. 

 3, 3. The triangular tissue, supposed to be muscular under the mucous membrane of 

 the vcsical triangle. 4, 4. Part of the detrusor urina muscle. 5. The elastic band 

 which acts as a constant sphincter to the neck of the bladder. G. 



Fig. 1584 





