ANATOMY OF FEMALE REPRODUCTIVE ORGANS-audio

The vulva or pudendum includes all the visible external genital organs in the perineum. Vulva consists of the following: The mons pubis, labia minora, hymen, clitoris, vestibule, urethra and Skene’s glands, Bartholin’s glands and vestibular bulbs ( Fig. 1.1). It is therefore bounded anteriorly by mons pubis, posteriorly by the rectum, laterally by the genitocrural fold. The vulvular area is covered by keratinized stratified squamous epithelium.

MONS VENERIS (MONS PUBIS): It is the pad of subcutaneous adipose connective tissue lying in front of the pubis and in the adult female is covered by hair. The hair pattern (escutcheon) of most women is triangular with the base directed upwards.

LABIA MAJORA: The vulva is bounded on each side by the elevation of skin and subcutaneous tissue which form the labia majora. They are continuous where they join medially to form the posterior commissure in front of the anus. The skin on the outer convex surface is pigmented and covered with hair follicle. The thin skin on the inner surface has sebaceous glands but no hair follicle. The labia majora are covered with squamous epithelium and contain sweat glands. Beneath the skin, there is dense connective tissue and adipose tissue. The adipose tissue is richly supplied with venous plexus which may produce hematoma, if injured during childbirth. The labia majora are homologous to the scrotum in the male. The round ligament terminates at its upper border.

LABIA MINORA: They are two thin folds of skin, devoid of fat, on either side just within the labia majora. Except in the parous women, they are exposed only when the labia majora are separated. Anteriorly , they divide to enclose the clitoris and unite with each other in front and behind the clitoris to form the prepuce and frenulum respectively. They lower portion of the labia monora fuses across the midline to form a fold of skin known as fourchette. It is usually lace rated during childbirth. Between the fourchette and the vaginal orifice is the fossa navicularis. The labia minora contain no hair follicles or sweat glands. The folds contain connective tissues, numerous sebaceous glands, erectile muscle fibers and numerous vessels and nerve endings. The labia minora are homologous to the penile urethra and part of the skin of penis in males.

CLITORIS:

It is a small cylindrical erectile body, measuring about 1.5-2 cm situated in the most anterior part of the vulva. It consists of a glans, a body and two crura. The clitoris consists of two cylindrical corpora cavernosa (erectile tissue). The glans is covered by squamous epithelium and is richly supplied with nerves. The vessels of the clitoris are connected with the vestibular bulb and are liable to be injured during childbirth. Clitoris is homologous to the penis in the male but it differs in being entirely separate from the urethra. It is attached to the under of the symphysis pubis by the suspensory ligament.

VESTIBULE:

It is a triangular space bounded anteriorly by the clitoris , posteriorly by the fourchette and on either side by labia minora. There are four opening into the vestibule.

(a)Urethral opening: The opening is situated in the midline just in front of the vaginal orifice about 1 – 1.5 cm below the pubic arch. The paraurethral ducts either on the posterior wall of the urethral orifice or directly into the vestibule.

(b)Vaginal orifice and hymen: The vaginal orifice lies in the posterior end of the vestibule and is of varying size and shape . In virgins and nulliparae, the opening is closed by the labia minora, but in parous, it may be exposed. It is incompletely closed by a septum of mucous membrane, called hymen. The membrane varies in shape but is usually circular or crescentic in virgins. The hymen is usually ruptured at the consummation of marriage. During childbirth, the hymen is extremely lacerated and is later represented by cicatrized nodules of varying size, called the carunculae myrtiformes. On both sides it is lined by statified squamous epithelium.

(c)Opening of Bartholin’s ducts: There are two Bartholin glands (greater vestibular gland), one on each side. They are situated in the superficial perineal pouch, close to the posterior end of the vestibular bulb. They are pea-sized and yellowish white in color. During sexual excitement, it secretes abundant alkaline mucus which helps in lubrication. The glands are of compound racemose variety and are lined by cuoidal epithelium. Each gland has got a duct which measures about 2 cm and opens into the vestibule outside the hymen at the junction of the anterior two-third and posterior one-third in the groove between the hymen and the labium minus. The duct is lined by columnar epithelium but near its opening by stratified squamous epithelium. Bartholin’s glands are homologous to the bulb of the penis in male.

(d)Skene’s Glands: are the largest paraurethral glands. Skene’s glands are homologous to the prostate in the male . The two Skene’s gucts may open in the vestibule on either side of the external urethral meatus.

VESTIBULAR BULB: These are bilateral elongated masses of erectile tissues situated beneath the mucous membrane of the vestibule. Each bulb lies on either side of the vaginal orifice in front of the Bartholin’s gland and is incorporated with the bulbo-cavernous muscle. They are homologous to the bulb of the penis and corpus spongiosum in the male . They are likely to be injured during childbirth with brisk hemorrhage.

PERINEUM: The details of its anatomy are described later in the chapter.

BLOOD SUPPLY: Arteries – (a) Branches of internal pudendal artery- they chief being labial, transverse perineal , artery to the vestibular bulb and deep and dorsal arteries to the clitoris. (b) Branches of femoral artery-superficial and deep external pudendal.

Veins- The veins form plexus and drain into: (a) Internal pudendal vein (b) Vesical or vaginal venous plexus and (c) Long saphenous vein. Varicosities during gregnancy are not uncommon and may rupture spontaneous causing visible bleeding or hematoma formation.

NERVE SUPPLY: The supply is through bilateral spinal somatic nerves- (a) Anterosuperior part is supplied by the cutaneous branches from the ilio-inguinal and genital branch of genito-femoral nerve (L1 and L2) and the posterior-inferior part by the pudendal branches from the posterior cutaneous nerve of thigh(S123). Between these two groups, the vulva is supplied by the labial and perineal branches of the pudendal nerve (S234).

LYMPHATICS: Vulval lymphatics have bilateral drainage. Lymphatics drain into -(a) Superficial inguinal nodes, (b) Intermediate groups of inguinal lymph nodes – gland of Cloquet and (c) External and Internal iliac lymph nodes.

DEVELOPMENT: External genitalia is developed in the region of the cranial aspect of ectodermal cloacal fossa; clitoris from the genital tubercle; labia minora from the genital folds; labia majora from the labio-scrotal swelling and the vestibule from the urogenital sinus.

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