INTERIOK OF THE BLADDER. 411 



closed by a small elongated prominence behind, uvula vesicce, occa- with the 

 sioned by a thickening of the submucous muscular and fibrous m 

 layers. This eminence is placed over the middle lobe of the pro- 

 state ; and from its anterior end a slight ridge is continued on the 

 floor of the urethra. 



About an inch and a half from the orifice of the urethra, and Openings of 

 rather more than that distance apart, are the two narrow openings 

 of the ureters (fig. 154). The tubes perforate the wall of the 

 bladder obliquely, lying in it for the distance of three-quarters 

 of an inch, so that the reflux of fluid through them towards the 

 kidney is prevented as the bladder is distended. Each terminates 

 by a slit-like opening in a prominence of the subjacent muscular 

 fibres. 



TRIGONE. 



Triangular surface. Immediately behind the orifice of the Trigone of 

 urethra is a smooth triangular surface, which is named trigone tb 

 (trigonum vesicse ; fig. 154, a). Its apex reaches the prostate, and 

 its base the ureters. Its boundaries may be marked out by a line how 

 on each side from the urethra to the ureter, and by a transverse *" 

 one, behind, between the openings of the ureters. This surface part cprre- 

 corresponds with the triangular space externally at the base of the JSSrnaify. 

 bladder, between the vesiculaB seminales and vasa deferentia. Over 

 it the mucous coat is more closely united to the muscular, so as to 

 prevent the accidental folds occurring as in the other parts of the 

 empty bladder. 



Dissection. The arrangement of the fleshy fibres of the ureters To expose 

 will come into view on the removal of the mucous membrane from ureters? Oi 

 the lower third of the bladder. 



Ending of the fibres of the ureter. As soon as the ureter pierces Muscular 

 the outer and middle coats of the bladder, its longitudinal fibres are ureters, 

 thus disposed : the more internal and strongest are directed trans- 

 versely, and join the corresponding fibres of the other urine tube ; 

 while the remainder are continued down over the triangular surface, 

 and blend with the submucous layer of the bladder fibres. 



Blood-ves&l* and nerves. The source of the vesical arteries, and Arteries; 

 the termination of the veins, have been detailed. The vessels are veins ; 

 disposed in greatest number about the base and neck of the bladder. 

 Most of the nerves distributed to the bladder, though supplied from nerves of 

 the pelvic plexus of the sympathetic, are derived directly from the * 

 spinal nerves. The lymphatics enter the glands by the side of the Lymphatics, 

 internal iliac vessels. 



THE URETHRA AND PENIS. 



URETHRA (fig. 154). The tube of the urethra extends Urethra^ 

 from the neck of the bladder to the end of the penis, and has length; 

 an average length of about eight inches ; but it is shorter by one 

 inch during life. It is supported by the prostate, the triangular 

 ligament, and the spongy structure of the penis. The tube is 



