The mons pubis, or mons veneris, is the fat-filled cushion that lies over the symphysis pubis. After puberty, the skin of the mons pubis is covered by curly hair that forms the escutcheon. In women, it is distributed in a triangular area, the base of which is formed by the upper margin of the symphysis. In men, the escutcheon is not so well circumscribed.
Labia Majora
These structures vary somewhat in appearance, principally according to the amount of fat that is contained within the tissues. Embryologically, the labia majora are homologous with the male scrotum. The round ligaments terminate at the upper borders. After repeated childbearing, the labia majora are less prominent. They are 7 to 8 cm in length, 2 to 3 cm in width, and 1 to 1.5 cm in thickness, and are somewhat tapered at the lower extremities. In children and nulliparous women (see Fig. 2–1), the labia majora usually lie in close apposition, whereas in multiparous women, they may gape widely. They are continuous directly with the mons pubis above and merge into the perineum posteriorly at a site where they are joined medially to form the posterior commissure.
Before puberty, the outer surface of the labia is similar to that of the adjacent skin, but after puberty the labia are covered with hair. In nulliparous women, the inner surface is moist and resembles a mucous membrane, whereas in multiparous women, the inner surface becomes more skinlike. The labia majora are richly supplied with sebaceous glands. Beneath the skin, there is a layer of dense connective tissue that is rich in elastic fibers and adipose tissue but is nearly void of muscular elements. Unlike the squamous epithelium of the vagina and cervix, there are epithelial appendages in parts of the vulvar skin. A mass of fat beneath the skin provides the bulk of the volume of the labium, and this tissue is supplied with a rich plexus of veins.
Labia Minora
The labia minora vary greatly in size and shape. In nulliparous women, they usually are not visible behind the nonseparated labia majora. In multiparas, it is common for the labia minora to project beyond the labia majora.
Each labium minus is a thin fold of tissue that is moist and reddish, similar in appearance to a mucous membrane. The labia minora are covered by stratified squamous epithelium. Although there are no hair follicles in the labia minora, there are many sebaceous follicles and, occasionally, a few sweat glands. The interior of the labial folds is composed of connective tissue with many vessels and some smooth muscular fibers. They are supplied with a variety of nerve endings and are extremely sensitive. The tissues of the labia minora converge superiorly, where each is divided into two lamellae; the lower pair fuse to form the frenulum of the clitoris, and the upper pair merge to form the prepuce. Inferiorly, the labia minora extend to approach the midline as low ridges of tissue that fuse to form the fourchette.
Clitoris
The clitoris is the principal female erogenous organ. It is the homologue of the penis and is located near the superior extremity of the vulva. This erectile organ projects downward between the branched extremities of the labia minora. The clitoris is composed of a glans, a corpus, and two crura. The glans is made up of spindle-shaped cells, and in the body there are two corpora cavernosa, in the walls of which are smooth muscle fibers. The long, narrow crura arise from the inferior surface of the ischiopubic rami and fuse just below the middle of the pubic arch to form the corpus.
The clitoris rarely exceeds 2 cm in length. Its free end is pointed downward and inward toward the vaginal opening. The glans is usually less than 0.5 cm in diameter and is covered by stratified squamous epithelium that is richly supplied with nerve endings. The vessels of the erectile clitoris are connected with the vestibular bulbs.
There is a delicate network of free nerve endings in the labia majora, labia minora, and clitoris (Krantz, 1958). Tactile discs are found in abundance in these areas. Genital corpuscles, which are mediators of erotic sensation, vary considerably in number. These structures are abundant in the labia minora and in the skin that overlies the glans clitoris.
Vestibule
The vestibule is an almond-shaped area that is enclosed by the labia minora laterally and extends from the clitoris to the fourchette. The vestibule is the functionally mature female structure of the urogenital sinus of the embryo. In the mature state, the vestibule usually is perforated by six openings: the urethra, the vagina, the two ducts of the Bartholin glands, and, at times, the two ducts of the paraurethral glands, also called the Skene ducts and glands (Fig. 2–2). The posterior portion of the vestibule between the fourchette and the vaginal opening is called the fossa navicularis, and it is usually observed only in nulliparous women.
Reference:
Cunningham., 200 Williams Obstetrics 22 edition, Mc Graw Hill.
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