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The blood-supply of the bulb is derived, on each side, from the arteria bulbi vestibuli, branch of the internal pudendal.
GLANDULE VESTIBULARES MAJORES.
The greater vestibular glands (O.T. glands of Bartholin) are placed one on each side of the lower part of the vagina, and represent the bulbo-urethral glands in
FIG. 1036.-DISSECTION OF FEMALE PERINEUM TO SHOW THE CLITORIS, THE BULB OF THE VESTIBULE, AND THE LARGER VESTIBULAR GLANDS (D. J. Cunningham).
the male. They are often overlapped by the posterior ends of the bulbus vestibuli, and are covered by the bulbo-cavernosus muscle. Each is about the size and shape of a small bean, and possesses a long slender duct which opens into the rima pudendi in the angle between the attached border of the labium minus and the vaginal opening.
DEVELOPMENT OF THE URO-GENITAL ORGANS.
THE URO-GENITAL PASSAGES.
General Account. In tracing the developmental history of the uro-genital passages we may for convenience begin with an embryo of fifteen days old. About this time a duct, which runs in a longitudinal direction, and occupies a position on the lateral side of the protovertebral somites, begins to develop on each side of the body. With the exception of the anterior portion of the cloaca and the proximal part of the allantois, this duct, which has received the name of primary excretory or Wolffian duct, is the earliest formed structure from which, or in connexion with which, the parts of the adult urino-genital system arise.
The Wolffian duct serves as the canal, or duct, for the primitive secretory organsthe pronephros and the mesonephros of the embryo. With the atrophy of these the duct suffers modification, yet both sexes in the adult possess structures which have their embryonic origin from the Wolffian duct. In the male the duct of the epididymis, the ductus deferens, and the ejaculatory duct, are to be looked upon as directly developed from the Wolffian duct of the embryo; while in the female the longitudinal duct of the ep-oöphoron and the appendices vesiculosi are rudimentary structures having a like origin. Further, the ureter and its pelvis arise in both sexes as an outgrowth from the Wolffian duct (Fig. 1037). In the male the vesicula seminalis is developed as a diverticulum of the Wolffian duct.
The primitive secretory organs, the pronephros and the mesonephros, develop in connexion with the anterior part of the Wolffian duct (p. 48), and, during the early life of the embryo, the latter of these is a most important structure. Even in the embryo
the latter about three and a half inches. At its lower end the vagina opens into ! the rima pudendi, the opening being situated behind the orifice of the urethra and the clitoris, and between the labia minora. The opening is partly closed in 1 the virgin by a thin crescentic or annular fold, called the hymen, torn fragments of which persist round the opening, as the carunculæ hymenales, after the fold itself has been ruptured.
Relations of the Vagina.-The anterior wall of the vagina in its upper part lies against the base of the bladder, but is separated from it by loose connective
tissue. Lower down, the anterior wall in the median plane is intimately connected with the urethra (Fig. 1033). Near the median plane, the posterior wall in its upper portion is covered for a distance of about a quarter of an inch by the peritoneum, which here forms the anterior boundary of the deepest part of the recto-uterine pouch. The depth to which the peritoneum of this pouch descends practically corresponds to the level of the spina ischiadica. Lower down, the posterior wall lies close against the rectum, from which it is separated by a layer of the pelvic fascia. As, however, the orifice of the vagina is approached, the rectum and vagina become separated by a considerable interval, which is occupied by a mass of fibrous and fatty tissue, often called the "perineum" or "perineal body." At the sides the vagina is supported by the levatores ani muscles. The terminal part of the ureter lies not far from the side wall of the upper part of the vagina, as it passes from above and behind downwards, medially and a little forwards to reach
the bladder. Near its termination the vagina pierces the fascia inferior of the urogenital diaphragm, and is related on each side to the bulbus vestibuli, the larger vestibular glands, and the bulbo-cavernosus (sphincter vagina) muscle.
Structure of the Vagina.-The vaginal wall has a distinct tunica muscularis, composed of unstriped muscle fibres, most of which are longitudinally disposed. Towards
FIG. 1034.-POSTERIOR ASPECT OF THE VAGINA, THE BASE OF BLADDER, AND THE RECTO-VAGINAL POUCH OF PERITONEUM.
The coccyx and the ligamentum sacrotuberosum and ligamentum sacrospinosum, together with the muscles attached to them, have been removed. The levatores ani have been separated along the median raphe, and drawn laterally. A considerable portion of the rectum has been removed, but the position which it occupied is indicated by the dotted lines. The peritoneum is indicated by a blue colour. The rectovaginal pouch is probably not quite so deep as usual. The triangular interval between the ureter and uterine artery was filled by a mass of fibro-muscular tissue, forming the lateral cervical ligament of the uterus.
the lower end of the passage circularly disposed bundles of striped muscle fibres, some of which are continuous with those forming a part of the urethral wall, are found in the muscular coat. The thick tunica mucosa, which has a stratified scaly epithelium, is corrugated, and presents a number of transverse ridges or elevations called rugæ vaginales. In addition to these transverse rugæ, a slightly marked longitudinal ridge, or column, is to be seen on the anterior and on the posterior wall of the vagina. These receive the name columnæ rugarum, and, like the transverse ruga, are best seen in young subjects and in the lower part of the vagina. The urethral canal lies in close relationship to the anterior column of the vagina in its lower part, and hence this portion of the anterior column is sometimes called the carina urethralis.
Within the tunica mucosa are to be found small collections, or nodules, of lymp tissue.
The vaginal wall is surrounded by a layer of loose vascular connective tissue containn, numerous large communicating veins.
Vessels and Nerves of the Vagina. The blood-supply of the vagina is for the most pa derived from the vaginal artery, the vaginal branch of the uterine artery, the vaginal brand of the middle hæmorrhoidal artery, and from the branches of the internal pudendal. The veins form a plexus surrounding the vaginal wall, and drain their blood into the tributaries of le hypogastric.
The lymph-vessels from the upper part of the vagina join the hypogastric group of glans. while those from the lower part end in the superficial inguinal glands.
The nerves of the vagina are derived from the plexus uterovaginalis and from the plexus vesicalis. Other fibres are derived directly from the third and fourth sacral nerves.
THE FEMALE EXTERNAL GENITAL ORGANS.
The term pudendum muliebre, or vulva, is applied collectively to the femal external genital organs, i.e. to the labia majora and the structures which lie between them.
Labia Majora.—The labia majora represent the scrotum in the male, and form the largest part of the female external genital organs. They form the boundaries. on each side, of the rima pudendi or uro-genital cleft, into which the urethra and vagina open. Each labium is a prominent rounded fold of skin, narrow behind where it approaches the anus, but increasing in size as it passes forwards and upwards to end in a median elevation, the commissura labiorum anterior, or the mons pubis or Veneris. The mons Veneris lies over the symphysis pubis, and, like the labia majora, it is composed chiefly of fatty and areolar tissue, and is covered with hair. The lateral convex surface of each labium majus is covered by skin containing numerous sebaceous glands and resembling that of the scrotum in the male. but the medial, flatter surface is smooth, and presents a more delicate integumentary covering. In some cases the posterior narrow ends of the labia majora are connected across the middle line, in front of the anus, by a slight transverse foldthe commissura labiorum posterior or posterior commissure.
Usually, especially in young adult subjects, the labia majora are the only visible parts of the external genital organs, since they are in contact with one another. and completely enclose the structures within the rima pudendi.
The round ligament of the uterus ends in the fatty tissue of the labium majus, The superficial subcutaneous tissue resembles that of the scrotum, but contains no muscular fibres.
The nerve-supply corresponds with that of the scrotum, the anterior part of each labium being supplied by the branches of the ilio inguinal nerve, and the posterior part by branches from the internal pudendal and by the perineal branch from the posterior cutaneous nerve of the thigh. The blood-vessels of the labia majora are derived from the external pudendal arteries and fre the perineal branches of the internal pudendal vessels.
Labia Minora. The labia minora pudendi (O.T. nymphæ) are a pair of much smaller and narrower longitudinal folds, usually completely enclosed within the cleft between the labia majora. Diminishing in size, and becoming less marked in their posterior parts, the labia minora end by gradually joining the medal surfaces of the labia majora. In the young subject, a slightly raised transvers fold is usually seen connecting the posterior ends of the labia minora; to this fold the term frenulum labiorum pudendi (O.T. fourchette) is applied. Trace forwards, each labium minus divides into two portions, a lateral and a media. The lateral portions of the two labia unite over the glans clitoridis, and form for it a fold or covering called the præputium clitoridis. The medi portions, uniting at an acute angle, join the glans and form the frenulum clitoridis. The skin of the labia minora resembles the integument on the medial or deep surface of the labia majora, being smooth, moist, and pink in colour. The media surfaces of the labia minora are in contact with one another; their lateral surfaces are applied against the medial aspects of the labia majora.
The openings of the urethra and vagina are placed in the median plane, in the interval between the labia minora, which must be separated to bring them into
Vestibulum vaginæ.-The vestibule is the name applied to the cleft that lies between the labia minora and behind the glans clitoridis. In its floor are the openings of the urethra, the vagina, and the minute ducts of the larger vestibular glands.
The fossa navicularis is the part of the vestibule placed behind the vaginal opening and in front of the frenulum labiorum pudendi.
The orificium urethræ externum, Præputium. or external urethral orifice, lies vaginæ (an-. immediately in terior part) front of that of the vagina, and is about one inch behind the glans clitoridis. The opening has the appearance of a vertical slit, or of an inverted Vshaped cleft, the slightly promineut margins of which are in contact. On each side of the urethral orifice there may sometimes be seen the minute opening of the ductus paraurethralis (see p. 1285).
The orificium vaginæ, or vaginal
FIG. 1035.-FEMALE EXTERNAL GENITAL ORGANS.
The frenulum labiorum is seen stretching across behind the fossa navicularis and in front of the posterior commissure. The ducts of the larger vestibular glands open in the intervals between the vaginal orifice and the medial edges of the labia minora.
opening, lies behind and below the orifice of the urethra. The appearance of the opening varies with the condition of the hymen-a membrane which in the young subject partly closes the aperture. When the hymen is intact the opening is small, and is seen only when the membrane is put on the stretch. When the hymen has been ruptured the opening is much larger, and round its margins are often seen small projections carunculæ hymenales-which are to be looked upon as persistent fragments of the hymen.
The hymen is a thin membranous fold, partially closing the lower end of the vagina, and usually perforated somewhat in front of its middle point. The position of the opening gives the fold, when stretched, a crescentic appearance. opening in the hymen is sometimes cleanly cut, sometimes fringed. The membrane is not stretched tightly across the lower end of the vagina, but is so ample that it projects downwards into the rima pudendi, and the parts of its upper surface are in contact with one another on each side of the opening. The opening is thus a median slit whose margins are normally in contact. The upper