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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 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 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
ladder. Near diaphragm stibular glands,
Structure of posed of unstrip
and drawn late
uterine arter the uterus
e bladder. Near its termination the vagina pierces the fascia inferior of the uronital diaphragm, and is related on each side to the bulbus vestibuli, the larger stibular glands, and the bulbo-cavernosus (sphincter vagina) muscle.
Structure of the Vagina.-The vaginal wall has a distinct tunica muscularis, mposed of unstriped muscle fibres, most of which are longitudinally disposed. Towards
Spina iliaca superior posterior
Apex of os sacrum
Incisura ischiadica major
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 lymph
The vaginal wall is surrounded by a layer of loose vascular connective tissue containing numerous large communicating veins.
Vessels and Nerves of the Vagina. The blood-supply of the vagina is for the most part derived from the vaginal artery, the vaginal branch of the uterine artery, the vaginal branch 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 the hypogastric.
The lymph-vessels from the upper part of the vagina join the hypogastric group of glands. 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 female 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 fron. 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 media! surfaces of the labia majora. In the young subject, a slightly raised transverse 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. Traced forwards, each labium minus divides into two portions, a lateral and a medial. 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 medial 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 medial surfaces of the labia minora are in contact with one another; their lateral surfaces re 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 view.
Vestibulum vagina. 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 vaginæ, or vaginal 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. The 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
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.
surface of the hymen is directly continuous with the vaginal wall, and on it are to be seen slight ridges continuous with the vaginal rugæ.
Developmentally the hymen appears to be a portion of the vagina.
On each side of the vaginal opening, and close against the medial side of the attached margin of the labium minus, is the minute opening of the duct of the glandula vestibularis major (O.T. Bartholin's gland). This is usually just large enough to be visible to the unaided eye.
Numerous minute mucous glands, the glandulæ vestibulares minores, open on the surface of the mucous membrane of the vestibule, between the urethral and orifices. The opening of the ductus para-urethralis at the side of the urethral orifice has been already noted,! p. 1285.
Clitoris. The clitoris is the morphological equivalent of the penis, and is composed of a body and two crura. Upon the summit of the body is a minute glans. Unlike the penis, the clitoris is not traversed by the urethra.
The corpus clitoridis is composed for the most part of erectile tissue resembling that of the penis in the male. It is about an inch or an inch and a half in length, and is bent upon itself, forming an angle open downwards. The body of the clitoris tapers towards its distal end, which is covered by the glans clitoridis. The organ is enclosed in a dense fibrous coat, and is divided by an incomplete septum, the septum corporum cavernosorum, into two symmetrical and somewhat cylindrical portions, the corpora cavernosa clitoridis. These represent the corpora cavernosa penis of the male, and diverge from one another at the root of the clitoris to form the crura clitoridis. A ligamentum suspensorium clitoridis passes from the fibrous coat of the body of the clitoris to the symphysis pubis (Fig. 1036).
The glans clitoridis is a small mass of erectile tissue which is fitted over the pointed end of the body. It possesses, like the glans penis, which it represents, a very sensitive epithelium. The præputium, or fold of skin which covers it, and the frenulum clitoridis, which is attached to it inferiorly, are continuous with the labia minora (Fig. 1036).
The crura clitoridis diverge from the body posteriorly, and are attached to the sides of the pubic arch. Each is continuous with one of the corpora cavernosa, and has a firm fibrous sheath, which is covered by the corresponding ischio-cavernosus or erector clitoridis muscle. In structure the crura and body of the clitoris resemble the corpora cavernosa penis, while the glans more closely resembles the bulbus vestibuli, with which it is continuous through a structure known as the pars intermedia.
In the seal and some other animals, a bone, which represents the os penis of the male, is developed in the septum of the clitoris. This bone receives the name os clitoridis.
Arteries and Nerves of the Clitoris.-Each crus receives a branch, the arteria profunda clitoridis, from the internal pudendal, while the glans is supplied by branches of the arteria dorsalis clitoridis.
The nerve-supply of the clitoris is derived partly from the hypogastric sympathetic plexus and partly from the dorsal nerves of the clitoris, which are branches of the pudendal nerves.
Bulbus Vestibuli.-The bulbus vestibuli is a mass of erectile tissue, in the female, which corresponds developmentally to the corpus cavernosum urethra of the male. In the female the fusion of the two halves of this structure is not nearly so complete as in the male, for the vagina and urethra separate the bulbus vestibuli into a right and a left portion which are only slightly connected in front by a narrow median part called the pars intermedia. Each half of the bulb is thick and massive posteriorly, and more pointed in front, where it joins the pars intermedia. It rests against the lateral wall of the vagina, and upon the superficial aspect of the fascia inferior of the urogenital diaphragm. It represents onehalf of the corpus cavernosum urethra of the male. Superficially it is covered by the bulbo-cavernosus muscle. The pars intermedia lies above the opening of the urethra, and becomes continuous with the tissue of the glans clitoridis.
The bulbus vestibuli is for the most part composed of minute convoluted bloodvessels, held together by a very small amount of connective tissue. These vessels frequently anastomose with one another, and those of each half communicate with the vessels of the pars intermedia and the glans clitoridis.