« PrécédentContinuer »
basal surface of the contracted and empty bladder receives a covering from the peritoneum, since the seminal vesicles and terminal portions of the ductus deferentes intervene as they lie in the anterior wall of the recto-vesical or rectogenital pouch. When the bladder is distended the posterior border, separating the upper and basal surfaces, is rounded out, and the peritoneum forming the horizontal shelf, just described, is taken up (compare Figs. 989 and 990). It is
Cavernons portion of urethra Bulb of urethra
FIG. 1001.-MEDIAN SECTION OF THE PELVIS IN AN ADULT MALE.
The coils of small intestine which lay within the pelvis have been lifted out in order to give a view of the side
to be specially noted that the level of the peritoneal reflection, forming the bottom of the recto-vesical pouch, does not vary much, as regards its relationship to the prostate, during distension and contraction of the bladder (Figs. 989 and 990).
An examination of median sections of the pelvis shows the great danger run by the ampulla of the ductus deferentes in any operation for reaching the bladder through the anterior wall of the rectum, and the difficulty in avoiding injury to the peritoneum.
The term "posterior false (or peritoneal) ligament" is often applied to the somewhat variable crescentic fold of peritoneum which bounds, on each side, the entrance to the recto-vesical or recto-genital pouch, and which often unites with
the fold of the opposite side across the median plane, behind the posterior border of the bladder and the ductus deferentes. These folds represent the plicæ rectouterinæ or folds of Douglas in the female, and are to be regarded as connexions of the ductus deferentes rather than of the bladder; hence the term sacro-genital folds is applicable to these structures in both sexes. The folds are seen in Figs. 990 and 995.
The peritoneum covering the upper surface of the empty or partly distended bladder often exhibits a transversely disposed fold or wrinkle, to which the term plica vesicalis transversa has been applied. This fold, when well developed, can be traced on to the side wall of the pelvis, where it traverses the paravesical fossa, and in some cases it is found to cross the pelvic brim and to be directed towards the abdominal inguinal ring (Fig. 995).
In the female the peritoneum is reflected posteriorly from the upper surface of the bladder on to the anterior aspect of the uterus.
Fixation of the Bladder. When the ligamentum umbilicale medium, or fibrous cord of the urachus, which binds the bladder apex to the anterior abdominal wall, and the peritoneal folds, already described as the false ligaments, are severed, the bladder is easily moved about, except in its lower and basal parts. Anteriorly it is connected to the pubis, and laterally to the fascial lining of the pelvis by loose areolar tissue only, which permits free movement during expansion and contraction. The lower fixed part of the bladder is held in place chiefly by processes of the pelvic fascia, continuous with those forming the sheath of the prostate. fascial connexions constitute the true ligaments of the bladder, and are described as pubo-prostatic or anterior ligaments, reaching the bladder from the pubis in front, and lateral ligaments, reaching the bladder from the fascial lining of the side wall of the pelvis.
In addition to the urachus and the peritoneal and the true ligaments already mentioned, the bladder is supported and fixed in position, in the region of its basal surface, by the dense fibrous and unstriped muscular tissue which surrounds the seminal vesicles, the terminal portions of the ductus deferentes and the ureters.
Laterally the strands of connective tissue and the bundles of muscle fibres forming this support pass backwards and are continued into the fascia which surrounds the branches of the hypogastric artery. Muscle fibres connected with the bladder wall are also found within the pubo-prostatic ligaments, through which they are attached to the pubis.
In the female the basal part of the bladder wall is supported and held in place by its connexion with the anterior wall of the vagina. The region of the urethral orifice is the most firmly fixed part of the bladder wall in both sexes.
Structure of the Bladder Wall.-The wall of the bladder from without inwards is composed of a serous, a muscular, a submucous, and a mucous coat. The tunica serosa or serous coat, formed by peritoneum, is incomplete, and covers only the upper and posterior parts of the distended bladder (Fig. 993).
A considerable amount of fibrous connective tissue surrounds the tunica muscularis or muscular coat, and penetrating it, divides it into numerous coarse bundles of muscle fibres. All the muscle fibres are of the unstriped variety, and the bundles which they form are arranged in three very imperfectly separated strata called external, middle, and internal. The stratum externum is for the most part made up of fibres which are directed longitudinally, and it is best marked near the median plane on the upper and under aspects of the bladder. Farther from the median plane, on the sides of the bladder, the fibres composing the external stratum run more obliquely, and their directions frequently cross one another. In the male, many of the fibres of the external stratum are attached both anteriorly and posteriorly to the prostate, and in the female the corresponding fibres. join the dense tissue which in this sex forms the upper part of the wall of the urethra. Other fibres of this stratum on each side of the body join the lower part of the symphysis pubis and constitute the musculus pubovesicalis, which lies in the substance of puboprostatic ligament. Lastly some fibres of the external stratum blend posteriorly with the anterior aspect of the rectum and receive the name of musculus rectovesicalis. stratum medium is composed of fibres which for the most part run circularly, and forms the greater part of the thickness of the muscular coat. In the region of, and
behind, the urethral orifice the bundles of fibres are finer and more densely arranged, and surround the opening in a plane which is directed obliquely downwards and forwards This part of the middle stratum is often spoken of as the "sphincter vesica." Inferiorly the fibres of the sphincter vesicæ are continuous with the muscular tissue of the prostate in the male, and with the muscular wall of the urethra in the female. In other parts of the bladder the bundles of the middle stratum are coarser and separated by intervals filled with connective tissue. The stratum internum is a thin layer of fibres directed for the most
The tela submucosa or submucous coat is composed of areolar tissue, but contains numerous fine elastic fibres.
The tunica mucosa or mucous coat is loosely attached, by means of the submucous layer, to the subjacent muscular coat, except in the region of the trigonum vesica, where the muscular fibres lie close beneath, and are firmly adherent to the mucous membrane. Over the trigonum the mucous coat is always smooth and flat; elsewhere it is thrown into folds when the bladder is empty. The mucous membrane of the bladder 18 continuous with that of the ureters and urethra. The epithelium, covering it, varies much in appearance in different conditions of the organ, and is of the variety known as transitional stratified epithelium. The appearance of the mucous coat is described on p. 1277.
Vessels and Nerves of the Bladder. The bladder receives its blood supply on each side from the superior and inferior vesical arteries. The inferior vesical artery arises from the hypogastric artery, and the superior vesical arises from the umbilical artery just before it becomes obliterated. The largest veins are found just above the prostate, and in the region where the ureter reaches the bladder. They form a dense plexus which pours its blood into tributaries of the hypogastric vein, and communicates below with the pudendal venous plexus. The lymph-vessels from the bladder join the iliac group of lymph-glands.
The nerve supply of the bladder is derived on each side from the vesical plexus, the fibres of which come from two sources, namely (1) from the upper lumbar nerves through the hypogastri plexus, and (2) from the third and fourth sacral nerves. The fibres from the latter sources j the vesical plexus directly.
The urethra is the channel which serves to convey the urine from the bladder to the exterior. In the male it consists of two portions, a proximal part, less than one inch in length, extending from the bladder to the points where the ducts of the reproductive glands join the canal, and a much longer distal portion which serves as a common passage for the secretion of the kidneys and for the generative products. An account of the male urethra follows the description of the male reproductive glands and passages (see p. 1304). In the female the urethra is more simple in its arrangement, and represents only the proximal part of the mal canal. It is a short passage leading from the bladder to the external urethral orifice an aperture placed within the rima pudendi or urino-genital cleft, imme diately above and in front of the opening of the vagina.
Urethra Muliebris.-The female urethra is a canal of about one to one and a half inches in length which follows a slightly curved direction downwards and forwards, below and behind the lower border of the symphysis pubis. As it leaves the pelvis the urethra pierces the urogenital diaphragm and its fascia and the part of the passage which lies between the superior and inferior layers of fascia is surrounded by the fibres of the sphincter urethræ membranace muscle. Except during the passage of fluid the canal is closed by the apposition of its anterior and posterior walls. The orificium urethræ externum or external orifice is placed between the labia minora, immediately in front of the opening of the vagina, and lies about one inch below and behind the clitoris (Fig. 1002 The opening is slit-like, and is bounded by slightly marked lateral lips. The posterior wall of the urethra, except in its upper part, is very intimately connected with the anterior wall of the vagina. The mucous lining of the canal is raised into a number of slightly marked longitudinal folds, one of which, more distinct than the others, and placed upon the posterior wall of the passage, receives the
name of crista urethralis.
Structure. The wall of the female urethra is thick and contains much fibrous tissue, which passes without any sharp line of demarkation into the surrounding mass of connective tissue. The tunica muscularis or muscular coat of the urethra is continuous above with that of the bladder, and is composed of layers of circularly and longitudinally disposed smooth muscle fibres arranged to form outer and inner strata. the muscular coat the wall of the urethra is very vascular, and the canal itself is lined by a pale mucous membrane which is thrown into longitudinally directed folds, one of which is the crista urethralis mentioned above. The epithelium of the canal, in its upper part, is of the transitional variety, like that of the bladder; in its lower part it becomes scaly. Numerous minute glands, the glandulæ urethrales, and pit-like depressions
FIG. 1002.-MEDIAN SECTION THROUGH THE FEMALE PELVIS. Drawn for the most part from a model of a dissection by Professor Edward H. Taylor.
(lacunæ urethrales) open into the urethral canal. One group of these glands on each side possesses a minute common duct known as the ductus paraurethralis, which opens into the rima pudendi or urino-genital cleft by the side of the urethral orifice. It is believed that these latter glands represent the prostatic glands of the male subject. The vascular layer which lies between the muscular coat and the mucous membrane contains elastic fibres, and in appearance resembles erectile tissue. Striped muscle fibres are present on the outer aspect of the muscular coat of the urethra. In the upper part of the canal these fibres form a complete ring-like sphincter, but in the middle and lower parts the striped muscle fibres though present in front are absent on the posterior wall of the urethra, as at this level they pass backwards on the outer aspect of the vagina, and enclose this latter passage together with the urethra in a single loop of muscle tissue. The lower fibres, therefore, form a urino-genital sphincter.
THE MALE REPRODUCTIVE ORGANS.
We have here to describe (1) the testes or essential reproductive glands of the male, together with their (2) coverings and (3) ducts, (4) the prostate, (5) the bulbourethral glands, (6) the external genital organs, and (7) the male urethra.
The reproductive glands of the male, or testes, are a pair of nearly symmetrical oval-shaped bodies situated in the scrotum. The duct of each gland, at first much twisted and intertwined, forms a structure known as the epididymis, which is applied against the posterior and lateral part of the testis. From the epididymis the excretory duct, or ductus deferens, passes upwards towards the inferior part of the anterior abdominal wall, which it pierces very obliquely, to enter the abdominal cavity. Here each ductus deferens is covered by the peritoneum, and almost at once crossing the pelvic brim, enters the pelvis. The duct now runs on the side wall of the pelvis towards the base of the bladder, where it comes into relation with a branched tubular structure termed the vesicula seminalis. Joined by the duct of the vesicula seminalis, the ductus deferens forms a short canal called the ejaculatory duct, which terminates by opening into the prostatic part of the urethra. The prostate, a partly glandular, partly muscular structure, surrounding the first part of the urethra, and also a pair of small glandular bodies called the bulbo-urethral glands, are accessory organs connected with the male
Head of epididymis Appendix of testis
reproductive system. The ducts of the bulbo-urethral glands and those of the prostate, like the ejaculatory ducts, open into the urethra, which thus serves not only as a passage for urine, but also for the generative products. The external genitals are the penis and
The male reproductive vaginalis glands, the testes, are a pair of somewhat oval, slightly flattened bodies of a whitish colour. measuring about an inch and a half in length, one inch from before backwards, and rather less in thickness. Each testis is placed within the cavity of the scrotum in such a manner that its long axis is directed upwards, slightly forwards, and laterally, and usually the lef gland occupies a lower leve than the right. The testis (Fig. 1003) has two somewhat flattened surfaces, one of which. called the facies lateralis, or
FIG. 1003. RIGHT TESTIS AND EPIDIDYMIS, EXPOSED BY THE
lateral surface, looks backwards as well as laterally; the other, the facies medialis or medial surface, looks forwards as well as medially, and is usually the more flattened. The two surfaces are separated by two rounded borders, one of which the margo anterior, is the more convex and free; while the other, the margo posterior. is less rounded, and by it the organ is suspended within the scrotum. The epididymis and the lowest portion of the funiculus spermaticus, or spermatic cord, an