The external genitalia include the vulva that extends from the mons pubis to the anal opening. The mons pubis, a fat pad located over the symphysis pubis covered with pubic hair, protects the symphysis pubis during sexual intercourse. The labia majora, the two folds of skin that are composed of adipose tissue, sebaceous glands, and sweat glands, extend from the mons pubis to the perineum. The inner surface of the labia majora is pink, smooth, and moist.

Inside the labia majora are the labia minora, folds that join anteriorly at the clitoris and form a prepuce, or hood, and join posteriorly to form the frenulum. The labia minora contain sebaceous glands that produce lubrication for the vaginal area. The clitoris, located at the anterior end of the labia minora, is a small, cylindrical mass of erectile tissue and nerves. The skinfolds of the labia majora and labia minora form a boat-shaped area or fossa called the vestibule. Located between the clitoris and the vaginal orifice is the urethral meatus. The openings of Skene glands, usually not visible, are on either side of the urethral opening and secrete mucus.

Below the urethral meatus is the vaginal orifice, covered by the hymen, a fold of membranous tissue that covers a part of the vagina. The Bartholin glands, located on both sides of the vagina and not visible to the eye, secrete mucus (Fig. 23-1).

The internal genital reproductive organs (Fig. 23-2) are the vagina, the uterus, the cervix, the fallopian tubes, and the ovaries. The vagina, about 10 cm long, extends up and slightly back toward the rectum from the vaginal orifice to the cervix. It allows the passage of menstrual flow, receives the penis during sexual intercourse, and serves as the birth canal during delivery. The cervix (or neck of the uterus) separates the upper end of the vagina from the isthmus of the uterus. The junction of the isthmus and the cervix forms the internal os, and the junction of the cervix and the vagina forms the external os. The cervix allows the entrance of sperm into the uterus, allows the passage of menstrual flow, and secretes mucus and prevents the entrance of vaginal bacteria. During childbirth, the cervix can stretch to allow the passage of the fetus. The uterus, a pear-shaped organ, has two components: the corpus and the cervix. The corpus is divided into the fundus (upper portion), the body (central portion), and the isthmus (narrow lower portion). The uterus is usually situated in a forward position above the bladder at approximately a 45-degree angle to the vagina when standing. The endometrium, the myometrium, and the peritoneum are the three layers of the uterine wall. The endometrium, the inner mucosal layer, has glands that secrete an alkaline substance to keep the uterine cavity moist. A portion of the endometrium sheds during menses and childbirth. The myometrium is the middle layer that functions to expel the products of conception. The peritoneum is the outer uterine layer that covers the uterus and separates it from the abdominal cavity. The ovaries, small oval-shaped organs, are on the lateral sides of the pelvic cavity and produce ova, estrogen, progesterone, and testosterone. The ovum travels from the ovary to the uterus through the fallopian tubes.

The anal canal begins at the anal sphincter and ends at the anorectal junction. It is 2.5 to 4 cm long. Within the anus are the two sphincters that hold the anal canal closed, except when passing gas and feces. The external sphincter is composed of skeletal muscle and is under voluntary control. The internal sphincter is composed of smooth muscle and is under involuntary control by the autonomic nervous system. Just above the internal sphincter is the anorectal junction, the dividing point of the anal canal and the rectum. The rectum is lined with folds of mucosa, known as the columns of Morgagni, which contain arteries, veins, and visceral nerves. The rectum is the lowest portion of the large intestine and is approximately 12 cm long, extending from the end of the sigmoid colon to the anorectal junction. It enlarges above the anorectal junction and proceeds in a posterior direction toward the hollow of the sacrum and coccyx, forming the rectal ampulla. The inside of the rectum contains three inward foldings called the valves of Houston. The peritoneum lines the upper two-thirds of the anterior rectum and dips down so that it may be palpated where it forms the rectouterine pouch in women.