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The urethra, or canal by which the urine reaches the surface, leads from the bladder, its aperture lying in the median plane, not far from the openings of the ureters, but on a lower and anterior plane. The size and shape of the bladder, the thickness of its wall, and also to a great extent its relations, vary with the amount of distension, or contraction, of the organ. When the bladder is empty, or only slightly distended, it lies within the pelvis minor; as it becomes filled with urine it rises above the pubis, and crossing the pelvic brim, enters the
Dorsal vein of penis-Corpus cavernosum penis.. Corpus cavernosum
Cavernous portion of urethra
FIG. 989.-MEDIAN SECTION THROUGH THE PELVIS OF AN ADULT MALE SUBJECT.
a view of the side wall of the pelvic cavity.
tas pelvic cavite
2 the male, forming the recto-vesical or recto-genital pouch ; in the female > peritoneal depression, called the utero-vesical pouch, intervenes between ior surface of the uterus and the bladder (Fig. 996). The inferior part of ler lies below the peritoneum, and is for the most part directed towards ; floor. In the median plane it is supported by the symphysis pubis and the ic pad of fat; farther back in the male it rests upon the prostate and on part of the rectum, from the latter of which it is separated by the vesiculæ and the terminal parts of the ductus deferentes. In the female it rests
Sphincter urethrae membranaceæ
Sphincter urethræ membranaceae
The urinary bladder and rectum are both greatly distended.
anterior wall of the vagina. Laterally the bladder is supported by the ini muscles, and farther from the median plane it rests on each side on tor internus; it is separated from the layer of the pelvic fascia covering cles by loose areolar tissue. pening of the urethra, orificium urethræ internum or internal urethral placed in, or near, the part of the bladder wall which lies lowest in
cavity. The term neck, or cervix, is often applied to this region, the
bladder appearing as if it were suddenly constricted to form the urethra. The portion of the bladder wall posterior to the urethral orifice, which is directed in the male towards the anterior wall of the rectum and lies below and in front of the recto-vesical pouch, is called the fundus vesicæ or base of the bladder; it is closely related to the seminal vesicles and ampullæ of the ductus deferentes. The corresponding part of the bladder in the female rests against the anterior wall of the vagina. The term vertex vesicæ, or apex of the bladder, is applied to the portion which lies nearest to the upper border of the symphysis when the organ is empty, Apex of bladder
and rises high above the pubis into the abdominal cavity when the bladder
is distended. Connected with the -Lateral border
vertex of the bladder is a fibrous cord, Infero-lateral
the ligamentum umbilicale medium, or
urachus, which passes upwards, in the Area continuous median plane, on the posterior aspect with prostate
of the anterior abdominal wall, and reaches the umbilicus. It represents the passage which in the em bryo
connects the developing bladder with - Ureter
the allantois. The part of the bladder FIG. 991.-INFERIOR ASPECT OF THE
apex with the base, and URINARY BLADDER. From a subject in which the not sharply marked off from either, is viscera had been hardened in situ.
called the corpus vesicæ, or body of The prostate has been severed from the bladder, and the the bladder. white area in the drawing indicates the position
Position of the Urethral Orifice. where the two structures were continuous.
-During the various changes in shape and size which the bladder undergoes, the region of the internal urethral orifice remains almost fixed in position. The urethral orifice lies immediately above the prostate, and behind and slightly below the level of the upper margin of the symphysis pubis, from which it is distant about two to two and a half inches. It can be easily reached by a finger introduced into the bladder through the abdominal wall above the symphysis pubis. It is usually placed half an inch to one inch above the level of a plane passing through the lower margin of the symphysis and the lower end of the sacrum, but in some
Bladder apex cases it is found to be somewhat lower. In the female it normally occupies a lower level than in the male. The comparatively slight variations in the level of the internal urethral orifice which do occur, depend partly upon the quantity of fluid contained in the
Ureth bladder, and partly upon the amount of distension of the lower portion of the rectum. When the bladder is very much distended this region lies at a slightly lower level in the pelvis than it does when the organ is empty; on the other hand, distension of the
Posterior surface of prostate lower part of the rectum raises, to some
Seminal vesiese extent, the level of the urethral orifice. Fig. 992.—THE URINARY BLADDER, PROSTATE. Since the position of the internal SEMINAL VESICLES, VIEWED FROM BELOV urethral orifice varies, in the manner Taken from a subject in which the viscera were berdeel just described-with the condition of
in situ. Same specimen as Fig. 993, A. The bladder
contained but a small amount of fluid. the rectum and of the bladder—it follows that it lies at its lowest limit when the bladder is full and the rectum empty, and at its highest level when the bladder is empty and the rectum distended
Inferior Aspect of the Bladder.-The lower part of the bladder, which is directed amount of distension of the viscus. When the organ has been carefully hardedel towards the pelvic floor, changes, as we have seen, but slightly with the varying
removal from the body, it is possible to map out on its inferior aspect three riangular areas, which may be distinguished from one another by the 3 in which they look. The three areas approach one another in the the urethral orifice, where, in the male, a portion of the inferior aspect of ler wall is structurally continuous with the upper part of the prostate. to the urethral orifice is a triangular district, directed downwards and backd related, in the male, to the seminal vesicles and the terminal portions ctus deferentes, which, together with the recto-vesical layer of the pelvic tervene in this position between the bladder and the rectum. This r area is known as the fundus, base, or postero-inferior surface of the ind in the female it is directed against the anterior wall of the vagina. of the inferior aspect of the bladder is formed by two infero-lateral urfaces, which meet in the median plane in front of the urethral orifice, irected for the most part downwards and laterally (see Fig. 993). Each of s extends backwards to join the fundus or postero-inferior surface, along border which lies between the point where the ureter reaches the bladder irethral orifice. The infero-lateral part of the bladder wall rests on the sue covering the fascia of the levator ani and the obturator internus muscles, r the median plane, upon the os pubis and the retro-pubic pad of fat.
Lig, um. Seminal
ligament area of bladder
area of bladder
ree rounded borders which mark off the three triangular areas on the
rounded borders, but as long as the organ is empty, or nearly so, they
of the bladder, or points where the ureters join the organ. · They separate the superior surface from the infero-lateral portions of the inferior aspect of the bladder wall (Fig. 993, A). The posterior border stretches across between the posterior angles of the bladder, and separates the superior from the basal surface of the viscus. The superior surface is related in the male to coils of intestine; in the female it is related also to the anterior surface of the uterus. The lateral border of the empty bladder lies against the pelvic fascia just above, or at the level of, the arcus tendineus of the levator ani muscle. The ductus deferens crosses the side wall of the pelvis parallel to it, but at a considerably higher level. In median section the cavity of the empty and relaxed bladder often presents the appearance of a Y-shaped chink, the stem of the Y being represented by the urethra as it leaves the organ, and the two limbs by the narrow intervals between the superior surface and the under parts of the bladder wall which lie in front of and behind the urethral orifice. This related form is sometimes described as the diastolic condition of the empty bladder, and is found associated with a bladder wall of but little thickness, and with a concave upper surface. The condition is usually the result of an escape of fluid after death, when the bladder wall has lost the power of contracting. It does not represent
FIG. 994.- VIEW LOOKING INTO THE PELVIS FROM ABOVE AND SOMEWHAT BEHIND.
The bladder has been artificially distended.
A distinctly y-shaped
a normal condition of the organ in the living. The normal empty is strongly contracted, and its wall is thick and firm. appearance is not presented by its cavity in median section, but the interior of the organ is seen as a simple narrow interval continuous with the canal of the urethra
Distended Bladder. As the bladder fills with fluid the superior raised upwards from the infero-lateral and basal walls, and, at the same time, the borders separating the superior from the other surfaces of the bladder becomes first more rounded and then nearly obliterated. The lateral borders of the bladder becoming in this manner opened out, give rise to so-called lateral surfaces in the distended organ. and are directly continuous with the superior surface.
These surfaces, however, are not sharply marked of also, the angles present in the empty condition of the organ become round
During distension as the entire bladder wall becomes more uniformly convex.
The shape of the bladder becomes altered during distension; the tetrahedra of the empty organ is lost, and the bladder as it becomes filled assumes somewhat spherical, then an oval contour. bladder comes to occupy more and more of the pelvic cavity, displacing upwa
During distension the en larg the portions of the colon and small intestine which may lie in the pelvis when the
. Until all the available pelvic space has been filled up, the form
genera i forn