OF THE BLADDER AND PROSTATE. 
39 
sphincter, the sphincter relaxing simultaneously and affording a clear channel for the 
escape of the fluid contents of the bladder *. 
The ureters enter the vesical parietes at a very obtuse angle, and the angle increases 
according to the degree of distention of the bladder. They receive accessions of fibres 
from the longitudinal, slightly oblique, oblique, and very oblique external and internal 
fibres in their vicinity, and are continued upon each other within the bladder in the form 
of a strong transverse band. The transverse band which connects the ureters together 
within the bladder, or between the uretral orifices, is equal in volume to the ureters 
themselves within the vesical parietes. It is best seen when the base of the bladder is 
detached and held against the light, and seems to be formed by a partial obliteration of 
the uretral tubes. 
The uretral canals seek the internal surface of the bladder even more obliquely than 
the ureters, and the inner surfaces of the ureters become so thin, particularly towards 
the uretral orifices, that they act mechanically as moveable partitions or valves, as in 
the smaller veins. The canals of the ureters are consequently closed, partly by the con- 
tractions of the muscular walls, and partly by the mechanical pressure exercised by the 
urine about to be expelled. 
From the foregoing resume it will be evident that the various sets of external and 
internal fibres forming the bladder, urethra, and prostate are arranged so as to coor- 
dinate each other, the loops formed by the anterior fibres crossing each other at 
more or less acute angles according to their depths, the anterior fibres, as a whole, 
crossing the posterior or homologous fibres as a whole. While, therefore, the fibres, in 
virtue of their twisted looped arrangement, coordinate each other individually, the 
aggregation of the fibres in any one region coordinate a similar aggregation of fibres at 
an opposite point, the anterior fibres, e. g., acting on the posterior, and the right lateral 
upon the left lateralf . This arrangement, which is productive of great strength, ensures 
that the external and internal fibres shall act in unison or together, and fully explains 
the views of the older anatomists, who described the bladder as consisting of fibres 
crossing in every direction, and forming an intricate network. It likewise accords with 
the more modern opinion, that the fibres of the bladder may be divided into strata 
or layers. 
It is difficult to estimate the precise effect which the twisted looped arrangement of 
the fibres may have on the contraction of the bladder ; but the fibres are disposed so 
* The structures which take part in the expulsion of the urine have been tabulated by Sir Charles Bell as 
follows : — “ The proper internal sphincter of the bladder, the compressor prostator, the levator ani, the levator 
or compressor urethrae of Mr. Wilsof, the ejaculator seminis, the internal and oblique perinal muscles. These, 
he says, are of the class of sphincter muscles, their opponents being the detrusor urinae or muscular coat of the 
bladder (and in consent with it), the abdominal muscles and diaphragm.” This author, it will be observed, 
makes no mention of the verumontanum. 
t The principle here foreshadowed seems to attain its full development in the voluntary system of muscles 
where the extensors coordinate the flexors, the abductors the adductors, the pronators the supinators, &c. 
