398 SURGICAL APPLIED ANATOMY. [Chap. xvin. 



are very apt to irritate that part of the interior. The 

 same remark applies to foreign bodies in the viscus. 

 The mucous membrane about the trigone and neck is 

 very sensitive, whereas the interior of the remainder 

 of the bladder appears to be singularly defective in 

 common sensation. This can be well noted in using 

 sounds and catheters. 



In the muscular coat of the viscus the fibres 

 are collected into bundles which interlace in all direc- 

 tions. When the bladder becomes hypertrophied 

 these bundles are rendered very distinct, and produce 

 the appearance known as "fasciculated bladder." 

 This simply means that the muscle of the bladder, 

 having been unduly exercised to overcome some 

 obstruction to the escape of urine, increases in size, 

 as do other much exercised muscles, and that increase 

 serves to demonstrate the arrangement of the indi- 

 vidual bundles. In a fasciculated bladder the muscular 

 bundles present much the appearance of some of the 

 columnse carnese in the heart. It will be understood 

 that the bladder wall between the muscular bundles 

 is comparatively thin, and may yield when the viscus 

 is distended. By such distension the mucous mem- 

 brane becomes bulged out between the unyielding 

 muscle bundles, so that sacculi are formed, and the 

 appearance known as " sacculated bladder " is pro- 

 duced. In these sacculi urine may lodge and decompose, 

 phosphatic deposits may collect, and calculi may 

 develop (encysted calculi). In some cases the parietes 

 yield, especially at one part, and one large saccule is 

 produced. In this way a sacculus may be formed 

 which in time may become almost as large as the 

 bladder itself, and give rise to the erroneous descrip- 

 tions of " double bladder," etc. 



The anterior wall of the bladder is thicker and 

 stronger than the posterior, and in cases of hypertrophy 

 the increase appears to mainly involve the anterior 



