130 MUSCULAR COAT OF THE BLADDER. 



— The diameter of the bas fond or lower fundus Is rather 

 greater laterally than in the antero-posterior direction. Its 

 lateral portions in both sexes are in contact with the levator aiii 

 muscles, and correspond to the spaces between the anus and 

 the tuberosities of the ischium. In the female, its middle por- 

 tion is in contact with the walls of the vagina ; in the male 

 with the rectum in the middle line, and with the vesiculae semi- 

 nales and the vasa deferentia upon the side. — 



The bladder is composed of a coat consisting of muscular 

 fibres, of a stratum of cellular substance immediately within 

 this, and of an internal lining membrane, which has been called 

 villous ; but, as there are no villi perceptible on it, it may 

 be more properly denominated mucous. 



It should be observed, that, in addition to these coats, the 

 bladder has a peculiar investment of the peritoneum, as has- 

 been already described ; and also of the common cellular mem- 

 brane, which is placed between it and every part to which it is 

 contiguous. 



The Muscular Coat of the Bladder consists of fibres which 

 are not spread over it of a uniform thickness, but are thin in 

 some places, and in others are collected in fasciculi. They run 

 in every direction : some appear longitudinal, others circular, 

 and some oblique ; and there are interstices between them 

 which are occupied by cellular membrane. The longitudinal 

 fibres originate from the lower part of the bladder ; and as this 

 is the fixed part of that viscus, it is the place from which these 

 fibres must necessarily act. These fibres are generally exte- 

 rior. There is no arrangement of the muscular fibres to which 

 the term of sphincter can properly be applied ; but many ana- 

 tomists have thought that the fibres near the neck of the bladder, 

 by their separate contraction, might prevent the escape of 

 urine ; this sentiment, however, is contrary to that of several 

 very respectable writers. 



The direction of the fibres, taken collectively, is such that, 

 when they all contract, the cavity of the bladder is completely 

 obliterated. 



— The longitudinal fibres form the detrusor urince muscle of 

 some anatomists. They commence at the front and inferior part 



