246 



Dr. Pettigrew on the Muscular Fibres 



[June 21, 



come more and more oblique, both from without and from within, or in 

 proportion as the centre of the vesical parietes is reached, the deepest or 

 most oblique external and internal sets forming, by the blending of their ter- 

 minal or transverse portions, what is commonly known as the central layer. 



The most external or superficial fibres are connected directly and in- 

 directly with the slightly oblique external fibres, the shghtly oblique with 

 the oblique, and the oblique with the very oblique. The very oblique ex- 

 ternal fibres, on the other hand, are connected with the oblique internal, 

 these in their turn being connected with the slightly oblique internal, and 

 the slightly oblique internal with the longitudinal or vertical internal. In 

 some instances the longitudinal external are connected directly with the 

 longitudinal internal, and so of the slightly oblique, oblique, and very oblique 

 external and internal fibres. 



The apex and base of the bladder are similarly constructed, and resem- 

 ble in their general configuration the other portions of the vesical walls ; 

 i. e., they are composed of longitudinal or vertical, slightly oblique, oblique, 

 and very oblique or circular fibres which cross in given directions on the 

 external and internal surfaces. 



The four sets of longitudinal or vertical fibres have a crucial arrangement 

 at the apex and base, and the slightly oblique fibres are drawn together at the 

 urachus and cervix by the constrictions which in the embryo separate the 

 bladder from the allantois and urethra. The slightly oblique fibres conse- 

 quently converge towards the apex and base respectively ; and this arrange- 

 ment at the cervix greatly assists in closing the urethra, as the fibres naturally 

 come together to form an impervious funnel-shaped projection which is di- 

 rected downwards and forwards. The closure of the urethra is completed by 

 the contraction of the very oblique or circular fibres forming the sphincter, 

 and by the prominence of the uvula vesicae (luette vesicale) and median ridge 

 in the female, and the caput gallinaginis or verumontanum in the male. 



The longitudinal or vertical, shghtly oblique, oblique, and very oblique 

 external and internal fibres at the base are continued forward within the 

 prostate to the membranous portion of the urethra, and the external and 

 internal surfaces of the corpus spongiosum. 



The coats of the urethra are therefore to be regarded as the proper con- 

 tinuation of the walls of the bladder in an anterior direction. 



The longitudinal or vertical, slightly oblique, oblique, and very oblique 

 spiral fibres which form the tunics of the bladder and urethra are curiously 

 enough repeated in the prostate of the male, and the analogous structure 

 n the female, so that this gland would seem to be composed chiefly of 

 fibrous offsets from the fibres in question. 



The relations existing between the prostate, urethra, and cervix of the 

 bladder are best seen when vertical, horizontal, and antero-posterior or 

 transverse sections of the bladder and prostate are made. 



In such sections the external longitudinal or vertical anterior, posterior, 

 and lateral fibres are seen to pass forward on the external surface of the 



