THE BLADDER. 81 



of the mucous membrane depending upon the subjacent third 

 lobe of the prostate; which, at this point, is not unfrequently 

 much enlarged in the aged, and then presents a great difficulty 

 in the introduction of a catheter. *^ 



3. The Orifices of the ureters form the posterior angles of the 

 triangle, and are contracted somewhat below the size of the ca- 

 nals themselves. They are said, by Sir Charles Bell,* to be 

 furnished, each one, with a small fasciculus of muscular fibres, 

 which runs backwards from the orifice of the urethra, just be- 

 neath the lateral margins of the triangle, and, in its contraction, 

 will stretch the orifice of the ureter so as to permit an easy 

 passage of the urine into the bladder. The retrogradation of 

 the urine is prevented by the ureter passing obliquely, for six or 

 eight lines, between the muscular and the mucous coat; there is 

 something also in the obliquity of the orifice itself which assists 

 in this effect ; as I have ascertained by removing the muscular 

 coat entirely, at this point, and dissecting up the ureter, not- 

 withstanding which, the bladder, when inflated, still retained its 

 contents. Where* the ureter penetrates the muscular coat, there 

 is often found a layer of longitudinal muscular fibres enveloping 

 it for half an inch, or an inch. 



4. The Inferior Fundus of the bladder (bas-fond of the French) 

 is a depression of the general concavity of the bladder, of about 

 six lines in depth, placed between the base of the triangle and 

 the posterior side of the bladder. In the erect position, calcu- 

 lus, when one has it, lodges there. 



5. The Internal Orifice of the neck of the bladder resembles 

 strongly that of a Florence flask, modified, however, by the 

 projection of the uvula vesicae, which makes it somewhat cres- 

 centic below. The neck of the bladder penetrates the prostate 

 gland, but, at its commencement, is surrounded by loose cellu- 

 lar tissue containing a very large and abundant plexus of veins.t 

 The internal layer of muscular fibres is here transverse; and 

 they cross and intermix with each other in different directions, 



* Med. Chir. Trans. Vol. iii. 

 * f Mascagni, Anat. Univ. Str. Prim. Tab. Spec. Fig. V. 



