THE BLADDER. 447 



in folds. These folds and vessels diminish or disappear when the bladder is distended. 

 The membrane at the trigone is more firmly connected to the muscle beneath than 

 elsewhere in the bladder, hence its smoothness and increased color. The muscular 

 coat is composed of two longitudinal layers with one more or less transverse layer 

 between. The external layer is continuous with the ureters, and over the prostate 

 to be attached to the lower posterior part of the pubes under the name of pubo- 

 vesical muscle. The circular fibres are continued around the opening of the urethra, 

 forming the internal sphincter. The openings of the ureters are not closed by mus- 

 cular action, but by the interior pressure. When the bladder is distended, if the 

 ends of the ureters are thickened they do not close as the urine accumulates, but 

 allow it to back up and distend the ureters and pelvis and even cause the kidney itself 

 to become enlarged. Thus infection ascends from the bladder to the kidney and 

 the ureters become distended until they may equal in size the small intestine. 



The fibres of the muscular coat pass in various directions, more or less in the 

 form of bundles. When these bundles become hypertrophied they can be seen as 

 distinct ridges on the interior of the bladder. In sounding they can be felt and 

 recognized by the tip of the sound. Such a condition is called a ribbed bladder. If 

 the bladder becomes hyperdistended the fibres become separated and the mucous, 

 membrane bulges out, forming a sac. It is then called a sacculated bladder. These 

 sacs are favorite lodging places for vesical calculi. From diseases of the prostate 

 and urethra the muscular coat becomes thickened. It is then called a hypertrophied 

 bladder ; such a one is usually contracted. 



The bladder walls ordinarily are quite thin, about 3 mm. (^ in.) thick. When 

 hypertrophied they are three or four times as thick. When the bladder is viewed in 

 life in abdominal operations it usually appears as a somewhat flaccid sac. It does not 

 assume the globular form until considerably distended and must contain a moderately 

 large amount of urine before showing above the symphysis. The commonly flaccid 

 condition of the bladder leads one to think that its emptying is largely favored by 

 the pressure of the intestines compressing it against the floor of the pelvis, and that it 

 is mainly in case of considerable distention or the pressure of irritation or disease that 

 its own muscular coat is utilized for the purpose. This view is strengthened by the 

 increase in flow when coughing and by the occurrence of bladder troubles (prolapse, 

 etc. ) so soon as the integrity of the pelvic floor is injured, as occurs in rupture of the 

 perineum from childbirth. The laxity of the bladder walls allows it to spread side- 

 wise to the neighborhood of the inguinal rings, and it has frequently been found in 

 the inguinal canal and has been wounded in operating for hernia. The urethral ori- 

 fice in the male is about 6.25 cm. (2)^ in.) from the surface at the upper margin of 

 the symphysis in a downward and backward direction; with the body in a vertical 

 position it might be said to lie on a level with the middle of the symphysis if the 

 bladder is empty, lower if the bladder is distended, and slightly higher if the rectum 

 is distended. It is therefore within easy reach of the finger inserted through a supra- 

 pubic incision. 



The Bladder in the Female. In the female the vesico-uterine pouch reaches 

 the level of the internal os and the bladder is in contact with the cervix from there 

 down to the cervicovaginal junction or anterior fornix. From here it is in contact 

 with the anterior vaginal wall along its upper half. The trigone extends from the 

 middle of the anterior vaginal wall, which marks the internal orifice of the urethra, 

 to 2 cm. ( y^ in. ) below the cervicovaginal junction, the spot where the ureters enter 

 the bladder walls. The absence of the prostate causes the bladder to be lower in the 

 female and the level of the internal urethral orifice is opposite the lower border of the 

 symphysis. It also is smaller in the female and does not show itself so readily above 

 the symphysis on distention. Vesicovaginal fistulae frequently occur as the result of 

 injuries during childbirth, cancerous ulceration, etc. They are located on the anterior 

 wall of the vagina above its middle. Calculi can be extracted through an incision 

 in the median line of the anterior vaginal wall above its middle. The commence- 

 ment of the ureters can also be palpated on each side of the cervix anteriorly and 

 impacted calculi may be removed at that point. The bladder is connected with the 

 cervix and vagina posteriorly by comparatively loose connective tissue so that they 

 can be readily separated by blunt dissection as far up as the internal os. 



