1866.] 



of the Bladder and Prostate. 



247 



urethra; a certain proportion passing outwards to be inserted into the 

 anterior, posterior, and lateral surfaces of the capsule of the prostate, others 

 passing inwards or through the gland in a vertical or longitudinal and like- 

 wise in a horizontal or transverse direction. The crucial arrangement of the 

 four sets of external fibres at the apex and base is thus clearly traceable in 

 the prostate. Such of the external fibres as are not inserted into the capsule 

 of the prostate are attached to the posterior surface of the pubis, the internal 

 border of the aponeurosis of the levator ani, and the fascia covering Guthrie's 

 muscle. The external fibres investing the dorsal, ventral, and lateral 

 aspects of the urethra and prostate are separated by a considerable interval, 

 thus showing that, although the relations existing between the urethra and 

 prostate are of the most intimate description, they may nevertheless be 

 regarded as independent. "What has been said of the external longitudinal 

 fibres applies equally to the slightly oblique, oblique, and very oblique 

 external and internal ones, these bifurcating and distributing themselves 

 with considerable regularity to the walls of the urethra, and the substance 

 of the prostate respectively. The urethra and prostate are thus com- 

 posed of fibres crossing in every direction as in the bladder itself. 



The very oblique external and internal fibres are interesting because of 

 the very obtuse angles at which they intersect, and because they are prin- 

 cipally concerned in forming the sphincter of the bladder, and the so-called 

 circular layer of the prostate. The very oblique fibres, like the other fibres 

 described, are arranged in an anterior and a posterior set, which are largely 

 developed, and a right and left lateral set, which are developed less feebly. 

 The anterior fibres, which are directed posteriorly, form the posterior half 

 of the sphincter vesicae, and the posterior fibres, which have an opposite 

 direction, the anterior. The sphincter is thus bilaterally symmetrical, and 

 is somewhat oval in shape, the long axis being directed transversely, or 

 from side to side. The two sets of lateral fibres, which also enter into the 

 formation of the sphincter, intersect the angles formed by the crossing of 

 the anterior and posterior fibres, and render its aperture more circular than 

 it would otherwise be. This circumstance, taken in connexion with the 

 fact that the fibres pursue a very oblique direction, has given rise to the 

 belief that the fibres of the sphincter and neck of the bladder generally are 

 circular fibres, which, as the author shows, is not the case. The fibres of 

 the sphincter are best seen by inverting the bladder and dissecting from 

 within, or by making transverse sections of the prostatic portion of the 

 urethra in the direction of the fundus. They are most strongly pro- 

 nounced at the cervix, but are continued forward on the urethra and 

 backwards into the bladder. In the female they extend even to the 

 meatus urinarius. The very oblique or circular fibres of the urethra are 

 separated from the corresponding fibres of the prostate by the longitudinal, 

 slightly oblique, and oblique fibres forming the outer half of the urethral 

 wall and the inner portion of the prostate. The interval is particularly 

 evident at the cervix, where the sphincter is most distinctly pronounced ; 



