648 URINARY BLADDER. 



appearance and the various directions they run, are called 

 the reticular. Some of these fasciculi are found to he quite 

 large, and from their projections and resemblance to the 

 columnas carneas, have heen called the columnar bladder- 

 This arrangement produces pouches or depressions for the 

 lodgment of calculi. 



The cellular or fibrous coat is between the muscular and 

 the mucous, and consists of fibres very compact, dense, 

 strong, elastic, extensible, difficult to tear, forming a 

 strong bond of union between the muscular and mucous 

 coats, and impervious to water. 



The fourth coat of the bladder is the inner or mucous, 

 called also the villous coat. Its color is rather pale, or of 

 a reddish white, and, in the contracted state, presents 

 many folds or wrinkles, which are effaced when distended. 

 It abounds with small mucous follicles, and is smoother 

 than the same membrane in the stomach. 



Several points are noticed on the inner surface of this 

 coat. First, is a small triangular space, below and behind 

 the neck of the bladder, known as the vesical triangle, (tri- 

 gone vesical.) This space forms an equilateral triangle, 

 about an inch in length, included between the orifice of 

 the urethra and those of the ureters. The openings for the 

 ureters form the posterior angles, while that of the urethra 

 forms the anterior. Mr. Bell traces a muscular bundle of 

 fibres, forming the lateral margins of the triangle, and 

 proceeding from the ureters to the mouth of the urethra, 

 designed he thinks to open the ureters and allow the free 

 entrance of the urine. This triangular space is smooth, 

 destitute of the wrinkles common to other parts of the 

 bladder, and is very vascular and sensitive. By the aid of 

 the lens numerous villi are detected. 



At the mouth of the urethra, or anterior angle of the 

 trigone, an eminence is observed, called the uvula vesicce. 

 This is situated about opposite the third lobe of the pros- 

 tate, and is formed by a projection of the mucous mem- 

 brane, which occasionally becomes an obstacle to the intro- 

 duction of the catheter. 



