External Female Genitalia
External female genitalia are part of the female reproductive system, and include:
- mons pubis
- labia majora
- labia minora
- vestibular bulb
- vestibular glands
External genitalia of a female occupy much of the perineum and are collectively referred to as the vulva (pudendum). They include the components below:
The mons pubis consists of a mass of subcutaneous adipose tissue anterior to pubic symphysis, and bears most of the pubic hair.
The labia majora (singular, labium majus) are a pair of thick folds of skin and adipose tissue found inferior to the mons. The fissure between the folds is called the pudendal cleft. Pubic hair can be found on the lateral surfaces of the labia majora once puberty hits, while the medial/internal surfaces will remain hairless. The round ligament of the uterus passes through the inguinal canal and continues into the labia majora, where the nerve fibers spread and mix with the tissue of the mons pubis. The labia majora are thicker in the front where they form by joining the anterior commisure, and is found below the mons pubis. The posterior commisure of the labia majora is the rear joining of the labia majora, and is located above the perineum.
Found medial to the labia majora are the labia minora (singular, labium minus), which are much thinner devoid of fat and entirely hairless. Their frontal ends split to form upper and lower layers. The upper layer goes superior to clitoris and forms a fold called prepuce. The lower layer passes inferior to clitoris and forms the frenulum of clitoris.
The labia minora enclose an area called the vestibule, which contains the urinary and vaginal orifices along with the openings of greater and lesser vestibular glands. A hoodlike prepuce over the clitoris is found at the anterior margin of the vestibule where the labia minora meet to form the prepuce.
The clitoris is analogous to the structure of the penis but it does not contain urethra and have no urinary role. It is richly supplied with autonomic efferent motor nerve endings via the cavernosal nerve of the clitoris and is highly sensitive to sexual stimulation. Also unlike the penis, the clitoris is nearly entirely internal and does not have a corpus spongiosum or enclose the urethra. The clitoris has a pair of corpora cavernosa which consist of erectile tissue enclosed in dense fibrous tissue. Each corpus (body) passes internally, and attached to the ischiopubic ramus by a crus. The suspensory ligament and two small muscles (ischiocavernosi) are attached to the crura just like the penis. The glans (head) of the clitoris is small tubercle, which protrudes slightly from the prepuce. Arteries here include the dorsal and clitoral cavernosal arteries, which arise from the iliohypogastric pudendal bed.
Vestibular bulbs are located on each side of the vestibule, consist of a pair of subcutaneous erectile tissues which correspond to penile bulb and corpus spongiosum. Both bulb join in front of urethral orifices under the vestibule of vagina. Each bulb is covered with bulbospongiosus muscles.
Bartholin’s (greater vestibular) glands are pea-sized with a short duct that opens into the vestibule or lower vagina is found on each side of the vagina. Bartholin’s glands are homologous to the bulbourethral glands in the male, and function to keep the vulva moist and provide lubrication for sexual intercourse during sexual excitement. Additionally, lesser vestibular glands lubricate the vestibule. Finally, a pair of Skene’s (paraurethral) glands, homologous to the male prostate, open into the vestibule nears the external urethral orifice.
The hymen is a structure that stretches across the vaginal opening and possesses one or more openings to allow for the discharge of menstrual fluid, and is usually ruptured to allow for sexual intercourse.
Vasculature of the vagina is primarily supplied by the vaginal artery, which is a branch of the anterior division of the internal iliac artery. Some of these arteries may be found on either side of the pelvis to and help to richly supply the vagina.
Lymphatic drainage of the vagina is generally to the external iliac nodes (upper 1/3 of the vagina), the common and internal iliac nodes (middle 1/3), and the superficial inguinal and perirectal nodes (lower 1/3).