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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

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Dorsal vein of penis-Corpus cavernosum penis.. Corpus cavernosum

urethra

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Anal canal
Membranous urethra
Bulb of urethra

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the

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Cavernous portion of urethra

FIG. 989.-MEDIAN SECTION THROUGH THE PELVIS OF AN ADULT MALE SUBJECT.
The urinary bladder is empty and firmly contracted. The coils of small intestine have been removed to afford

a view of the side wall of the pelvic cavity.
abdominal cavity. These changes affect chiefly the upper part of the bladder, which
becomes altered in shape and size, and acquires new connexions and relations
lower portion varies but slightly with the amount of distension of the orga
Figs. 989 and 990). The upper part of the bladder is covered with peritoneum,
is reflected on to it from the anterior abdominal wall in front, from the sides of the
pelvis laterally, and, in the male, across the seminal vesicles and terminal parts of
the ductus deferentes from the rectum behind. In the female the peritoneum
on to the bladder posteriorly from the anterior surface of the uterus.
peritoneum dips down posteriorly for a certain distance between the bladder and

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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

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Sphincter urethrae membranaceæ

Anal canal

Sphincter urethræ membranaceae
Bulb of urethra Bulbo-cavernosus muscle
Fig. 990.- MEDIAN SECTION OF the Pelvis OF AN ADULT MALE SUBJECT.

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

EMPTY

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

MALE
connecting 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

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Infero-lateral

Creter

Ductos defereby

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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.

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Lig, um. Seminal
bilicale vesicle
medium

Median
Infero-lateral

umbilical

ligament area of bladder

(urachus)
Lateral

Infero-lateral
Urethra

aspect of
prostate

area of bladder

Urethra
A

B
HE URINARY BLADDER, PROSTATE, AND VESICULA SEMINALIS, VIEWED FROM THE LATERAL ASPECT.
pecimens in which the viscera were hardened before removal from the ody. In A the bladder
ned but a very small quantity of fluid ; in B the quantity was somewhat greater. In A the
eum is shown covering the superior surface of the bladder, and its cut edge is seen where it is
ed along the lateral border of the organ. In B the level of the peritoneal reflexion is indicated by
d line.

ree rounded borders which mark off the three triangular areas on the
pect of the bladder, just described, extend from the region of the urethral
the bladder apex, and to the points where the ureters reach the bladder
igs. 991, 992).
and Relations of the Empty Bladder.—When the bladder is empty, or
it has, roughly speaking, the shape of an inverted tetrahedron, whose
sponds to the point where the urethra leaves the organ, while the base
ahedron is formed by the superior surface of the bladder. The three
es of the tetrahedron correspond to the bladder apex and to the two
gles of the bladder, or points where the ureters join the organ. The three
hich meet inferiorly at the urethral orifice, are only marked off from one

rounded borders, but as long as the organ is empty, or nearly so, they
ced by distinct borders from the superior surface. These three areas
already described as the infero-lateral surfaces and the base of the
igs. 991 and 992). Their relations have also been indicated. The
rface of the empty bladder looks upwards into the pelvic cavity; it is
n the organ is contracted, concave when relaxed. This surface is covered
neum, and its outline, which is approximately triangular, is determined
and posterior borders (Fig. 993). The lateral borders of the empty
sharply marked, and extend from the bladder apex to the posterior angles

1

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

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FIG. 994.- VIEW LOOKING INTO THE PELVIS FROM ABOVE AND SOMEWHAT BEHIND.

The bladder has been artificially distended.

bladder

A distinctly y-shaped

wall is

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

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