Female Reproductive System: Anatomy and Physiology

Know the structures cold, internal and external, and what each one does. This is the map behind every OB and gyn assessment you will run.

Internal Structures

Ovaries

The ovaries produce, mature, and discharge the ova, and they maintain the secondary sex characteristics. Each is almond-shaped, grayish white, and pitted like a raisin: about 4 cm long, 2 cm wide, and 1.5 cm thick. They sit proximal to both sides of the uterus in the lower abdomen. Each ovary has three layers: a protective epithelium, the cortex, and the central medulla.

Fallopian Tubes

The fallopian tubes carry the ovum toward the uterus. Each is a smooth, hollow tunnel in four parts: the interstitial (1 cm long), the isthmus (2 cm), the ampulla (5 cm), and the funnel-shaped infundibulum (2 cm). The funnel carries small hairs, the fimbria, that propel the ovum into the tube. The tube is lined with mucous membrane over connective tissue and a muscle layer, and that muscle layer drives the peristaltic movements that move the ovum forward. The distal ends are open, which makes a pathway for conception.

Uterus

The uterus is a hollow, muscular, pear-shaped organ in the lower pelvis, posterior to the bladder and anterior to the rectum. It runs about 5 to 7 cm long, 5 cm wide, and 2.5 cm deep at its widest part, and weighs roughly 60 g in a non-pregnant woman. It receives the ovum from the fallopian tube and provides a place for implantation, nourishment, and protection of the growing fetus. It has three parts: the body, the isthmus, and the cervix. The body is the uppermost bulk and the part that expands to hold the fetus. The isthmus is a short connection between body and cervix, and it is the portion cut during a cesarean section. The cervix lies half above the vagina and half extending into it, with an internal and external os opening into the cervical canal.

External Structures

Mons Veneris

A pad of fat tissue over the symphysis pubis, covered with coarse pubic hair. It protects the pubic bone from trauma.

Labia Minora

Two pinkish folds of connective tissue, mucous membrane on the internal surface and skin on the external surface, with sebaceous glands throughout.

Labia Majora

Two folds of fat tissue lateral to the labia minora, covered by loose connective tissue and epithelium and by pubic hair. They protect the external genitalia, distal urethra, and vagina from trauma and from bacteria.

Vestibule

A smooth, flattened surface inside the labia where the urethral and vaginal openings arise.

Clitoris

A small, circular organ of erectile tissue at the front of the labia minora, covered by a fold of skin called the prepuce. It is the center for sexual arousal, highly sensitive to touch and temperature.

Skene's Glands

Also called paraurethral glands. They sit lateral to the urethral meatus with ducts opening into the urethra, and their secretions lubricate the external genitalia during coitus.

Bartholin's Gland

Also called the bulbovaginal gland. It lubricates the external genitalia during coitus through ducts opening into the distal vagina. Skene's and Bartholin's secretions are alkaline to help sperm survive in the vagina.

Fourchette

A ridge of tissue formed where the labia minora and majora join posteriorly. This is the tissue cut during an episiotomy to enlarge the vaginal opening.

Perineal Body

A muscular area that stretches during childbirth. Pregnancy exercises like Kegels and squatting strengthen it for easier expansion and less tearing.

Hymen

A tough, elastic, semicircle of tissue covering the vaginal opening, torn during first sexual intercourse.