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of the distended bladder is spherical, or oval, with the larger end directed downwards 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 distended 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 triangular surface behind the urethral orifice, called the trigonum vesicæ, 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 vesicæ. Stretching across between the openings of 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 so as to be convex forwards. The lateral portions of the ridge which lie outside the openings of the ureters are called the plicæ uretericæ, and are produced by the terminal parts of the ureters as they traverse the bladder wall and lie beneath the mucous coat of the bladder (Fig. 995). In old people the region behind the trigonum is usually distinctly depressed and forms a shallow fossa, sometimes called the retro-ureteric fossa. A less distinct shallow depression may sometimes be observed on each side of the trigone. Round the urethral orifice are a number of minute radially disposed folds which, disappearing into the urethra, become continuous with the longitudinal folds of the mucous membrane of the first part
of that canal. The ureters pierce the bladder wall very obliquely, and so the minute orificium ureteris, or opening, of each has an elliptical outline. The lateral boundary of each opening is formed by a thin, crescentic fold, which, when the bladder is artificially distended in the dead subject, acts as a valve in preventing water or air from entering the ureter. Hence the term "valvula ureteris" is sometimes used to designate the fold. In the empty bladder the urethral orifice and the openings of the two ureters lie at the angles of an approximately equilateral triangle, whose sides are about one inch in length. When the bladder is distended the distance between the openings may be increased to one and a half inches or more. Bladder in the Female. In the female the bladder is related posteriorly to
FIG. 995.-EMPTY AND CONTRACTED URINARY BLADDER, OPENED UP BY THE REMOVAL OF ITS UPPER WALL The peritoneum is seen spreading out from the lateral and posterior borders of the organ. Compare with Fig. 1000.
the uterus and upper part of the vagina. [The anterior surface of the uterus in its upper part is separated from the upper surface of the bladder by the shallow uterovesical pouch of peritoneum, but the two organs are nevertheless normally in apposition. So close is this relationship that the upper surface of the bladder very often shows a slight concavity, due to contact with the convex anterior wall of the uterus. The lower part of the uterus and upper part of the vagina are not separated by peritoneum from the basal surface of the bladder, but are in actual apposition with it (Fig. 996). Thus, below the level of the utero-vesical pouch, the female bladder is related in much the same manner to the uterus and anterior wall of the vagina as the male bladder is related to the vesiculæ seminales and ductus deferentes. The apex of the bladder, where the urachus is attached, often lies on a lower level than in the male, so that the organ, even when distended, rises less freely into the abdomen. The bladder as a whole is placed deeper in the pelvis than in the male, and the internal urethral orifice lies just above, or just below, a line drawn from the lower margin of the symphysis to the lower end of the sacrum (p. 1274). The lower level of the internal urethral orifice is probably correlated with the absence of a distinct prostate in the female. It is probable that as regards capacity no difference exists between the bladder in the male and in the female; the conflicting results arrived at by different observers are probably due to the faulty methods which have been employed in estimating the capacity of the organ.
Bladder in the Newly Born Infant and in the Child.-At birth the empty
Cavity of uterus
Cavity of urinary bladder Labium anterius (cervicis uteri) Symphysis pubis
Labium minus pudendi
FIG. 996.-MEDIAN SECTION OF THE PELVIS IN AN ADULT FEMALE.
bladder is spindle- or torpedo-shaped, and its long axis, which extends from the point of attachment of the urachus to the internal urethral orifice, is directed downwards and backwards (Fig. 997). The lateral and posterior borders seen in the adult organ cannot be recognised at birth, nor is there any part of the bladder wall directed downwards and backwards, as is the basal surface of the adult organ. In the foetus and young child the bladder occupies relatively a much higher level than it does in the adult, and, even when empty, it extends upwards into the abdominal cavity. Its anterior aspect is in contact with the posterior surface of the anterior abdominal wall. At birth the peritoneum forming the recto-vesical pouch covers the whole of the posterior surface of the bladder, and reaches as low as the upper limit of the prostate. The internal urethral orifice is placed at a high level, and sinks gradually after birth (Fig. 998, A). In the newly born child this
Labium posterius (cervicis uteri)
Recto-vaginal reflexion of peritoneum
umbilical ligament (urachus)
wall of bladder
FIG. 997. THE URINARY BLADDER OF A NEWLY
opening lies on a level with the upper margin of the symphysis pubis, and the
We have already seen that the superior surface of the empty bladder is covered by peritoneum, which leaves it along the lateral border on each side to reach the pelvic wall at about the level of the arcus tendineus or white line
Internal sphincter ani
-External sphincter ani anterior reflection
lies just behind, or
toneal reflection forming the superior false ligament is raised upwards, and may
FIG. 998.-MEDIAN SECTION THROUGH THE PELVIS OF NEWLY BORN CHILD.
When the bladder is empty the peritoneum is carried downwards upon the side wall of the pelvis as low as the lateral border of the organ, and lines a shallow depression which receives the name of paravesical fossa. This peritoneal fossa lies below the level of the obturator peritoneal fossa (p. 1269), from which it is separated by the ductus deferens. As the bladder fills, the peritoneum is raised off this part of the pelvic wall, and certain structures, such as the obturator vessels and nerve
FIG. From a speci parave is bout
Trigonum femorale External iliac vessels
Median umbilical ligament (urachus) Urinary bladder
half an inch, giving at
the same time a partial FIG. 999.--VIEW LOOKING FROM ABOVE INTO THE PELVIS AND LOWER
A FETUS OF ABOUT THE
PART OF THE ABDOMINAL CAVITY IN
covering to the ductus de-
Internal spermatic vessels
the left side, which represents a slightly more advanced condition than the right, the testis has entered the inguinal canal; on the right side the testis is still within the abdominal cavity.
Obliterated umbilical artery
Internal spermatic artery
FIG. 1000.-VIEW LOOKING INTO THE MALE PELVIS FROM ABOVE AND SOMEWHAT BEHIND.
paravesical fossa is seen on each side of the bladder. The deep peritoneal pouch in front of the rectum is bounded on each side by crescentic sacro-genital folds or "posterior false ligaments of the bladder," which meet together in the median plane some distance behind the posterior border of the bladder.