THE UBINAKY BLADDER 1277 



of the distended bladder is spherical, or oval, with the larger end directed down- 

 wards and backwards. When the pelvic wall prevents further expansion of this 

 portion, the outline of the' organ may become an oval with the larger end directed 

 upwards and forwards into the abdominal cavity. The highest part of the dis- 

 tended bladder lies at some distance above the pelvic brim, and does not correspond 

 to the attachment of the urachus at the apex, but to a point farther back (Fig. 994). 

 As the superior wall of the bladder is raised up during distension it carries with it 

 the peritoneum, and thus the reflexion of that membrane, from the anterior 

 abdominal wall on to the apex of the bladder, comes to lie one and a half inches, or 

 even higher, above the upper margin of the symphysis pubis (Fig. 990). It is, 

 therefore, possible to puncture, or open into the distended bladder, through the 

 anterior abdominal wall above the symphysis pubis, without at the same time 

 opening into the peritoneal cavity. In a similar manner the line of reflexion of 

 the peritoneum, from the side wall of the pelvis on to the lateral aspect of the 

 bladder, is raised higher during distension, and may come to correspond, in part, to 

 the level of the ductus deferens, or to that of the obliterated part of the umbilical 

 artery. On the other hand, the level of the reflexion of the peritoneum from the 

 rectum towards the basal aspect of the bladder does not appear to vary much with 

 the distension, or contraction, of the organ (compare Figs. 989 and 990), and thus the 

 fossa between the bladder and rectum becomes relatively very deep when the bladder is 

 full. The bladder in normal distension may contain nearly one pint, but in most cases 

 the organ is emptied when its contents reach from six to ten ounces. Under abnormal 

 or pathological conditions the bladder capacity may be very much increased. 



Varying Relationships, according to the degree of Distension of the Bladder. 

 When the bladder is distended the obliterated part of the umbilical artery may 

 cross forwards against its side, but when it is empty the obliterated vessel at its 

 nearest point often lies as much as one and a quarter inches above the lateral 

 border of the organ. The ductus deferens, during a part of its course, is in contact 

 with the lateral wall of the distended bladder, but when the organ is empty it lies 

 above and parallel to the lateral border, only coming into relationship with the 

 basal surface of the bladder beyond the point where it crosses the ureter. The side 

 wall of the distended bladder is closely related to the obturator vessels and nerves. 



Interior of the Bladder. The mucous membrane lining the bladder is 

 loosely connected to the muscular coat, and when the bladder is contracted the 

 mucous lining of the upper wall is thrown into a number of prominent wrinkles 

 or folds (Fig. 995). At one place only the mucous membrane is firmly connected 

 to the subjacent muscular coat, and the inner surface of this part of the bladder 

 wall is smooth and free from wrinkles. This smooth area corresponds to a tri- 

 angular surface behind the urethral orifice, called the trigonum vesicse, and to the 

 part of the bladder wall which immediately surrounds the opening. The apex 

 of the triangle lies at the beginning of the urethra, and the base is formed by a 

 line drawn between the openings of the ureters into the bladder. Just behind 

 'the urethral opening the bladder wall sometimes bulges slightly into the cavity, 

 owing to the presence of the middle lobe of the prostate, which lies beneath the 

 mucous coat in this position. When well marked, as it often is in old people, 

 this bulging is termed the uvula vesicse. Stretching across between the openings 

 }f the ureters there is usually to be seen a smooth ridge, due to the presence of a 

 bundle of transversely disposed muscle fibres, which lies within this part of the 

 bladder wall, beneath the mucous membrane. This ridge has been called the 

 ' torus uretericus." It may be deficient near the median plane, and it is curved 

 .no as to be convex forwards. The lateral portions of the ridge which lie outside 

 jhe openings of the ureters are called the plicae uretericse, and are produced by the 

 terminal parts of the ureters as they traverse the bladder wall and lie beneath the 

 :nucous coat of the bladder (Fig. 995). In old people the region behind the 

 irigonum is usually distinctly depressed and forms a shallow fossa, sometimes 

 jailed the retro-ureteric fossa. A less distinct shallow depression may sometimes 

 3e observed on each side of the trigone. Eound the urethral orifice are a number 

 )f minute radially disposed folds which, disappearing into the urethra, become 

 i Continuous with the longitudinal folds of the mucous membrane of the first part 



