MUSCULAR LAYERS OF THE BLADDER. 127 



millimeters in thickness. This last is traversed in various 

 directions by numerous elastic fibres, and a not inconsiderable 

 number of smooth muscular fibres, which are partly isolated 

 and partly associated into fasciculi. 



Near the urethral orifice, solitary acinous glands are found 

 scattered here and there, similar to those met with in the pars 

 prostatica urethrse. They are by no means constant, and appear 

 to be especially infrequent during the earlier periods of life, 

 which is perhaps referable to their development taking place 

 long subsequent to birth. The relations of the vessels and 

 nerves will be discussed hereafter. 



III. THE MUSCULAR LAYERS. The fibres of the muscular 

 coat of the bladder are from 0*1 to 0'25 of a millimeter in 

 Jength, and possess a distinct elongated, rod-like nucleus. In 

 the urinary bladder of the Frog the muscular fibres are of 

 remarkable length, amounting to as much as 0'4 of a millimeter 

 or more. 



The fibres of the bladder in Man unite to form rounded 

 fasciculi and cords, having a diameter of 0'03 to 0' 15 of a milli- 

 meter, and being separated by septa of connective tissue, in 

 which run bloodvessels and nerves. These sheaths vary in 

 size, both locally and individually, but in general are much 

 thicker in children than in adults, and in the former may 

 equal or even exceed the muscles themselves. In the vicinity 

 of the sphincter vesicse the muscular fasciculi are completely 

 separated from one another, and enclosed by the interstitial 

 connective tissue, which so interpenetrates the fibres as either 

 to isolate them entirely, or to allow only a few to be combined 

 together. 



The course of these muscular fibres is by no means regular, 

 and differs in many particulars from any schematic repre- 

 sentation. 



If, however, such a representation be desired, the simplest, 

 and that most in accordance with facts, would be the following. 

 Most internally is a plexus of circular muscular fasciculi, 

 decussating at acute angles, and forming transverse meshes. 

 These fibres are particularly strongly developed at the ostium 

 internum urethrse ; here the course of the fasciculi is more 



