The uterus, or womb as it is commonly called, is part of the female internal genitals. It is a hollow, muscular organ about the size of a closed fist (three to four inches long and three inches wide) and is shaped like an upside-down pear. The upper end of the uterus is connected to the Fallopian tubes, and the lower, narrow end, called the neck, becomes the cervix, which extends into the back of the vagina.

The upper portion is the larger part, and it is here where a fetus grows and is nourished during pregnancy. The uterus is very thick-walled and quite elastic, as is demonstrated by its ability to expand enough to hold a growing fetus, then return to approximately its prior size after the birth of the baby.

Layers of the Uterus

The uterus is made up of three special layered linings of tissue and muscle.

  • The innermost layer is called the endometrium. After the onset of puberty, the endometrium lines the main body of the uterus and is where a fertilized ovum implants at the earliest moment of pregnancy. It provides a nesting place with immediate nutrition for the fertilized egg. If a woman is not pregnant, this lining is not needed, so it separates from the uterus and leaves the body as the menstrual flow during the menstrual period. This process is repeated monthly. Immediately a new lining begins to form in case a pregnancy occurs during the woman's next cycle. Except during a pregnancy or some abnormal circumstances, this series of events continues uninterrupted from puberty to menopause.
  • The second layer is called the myometrium. This gives the uterus its great strength and elasticity. The myometrium contracts during the birth process and forces the fetus out of the uterus into the birth canal.
  • The third layer is called the perimetrium. It is a thin external covering for the other two layers. The uterus is held loosely in place in the pelvic cavity by several sets of ligaments: the broad ligament, the round ligament and the uterosacral ligament.

Although the uterus is not directly involved in sexual activity, it does undergo changes during sexual excitement. When a woman is sexually aroused, the uterus lifts upward, increases in size and remains enlarged until orgasm or until stimulation stops.

The Uterus and Menopause

During and after menopause, the reduced supply of estrogen causes the uterus to shrink in size. It no longer enlarges in response to sexual stimulation as it once did, but the feelings of sexual excitation, orgasm and fulfillment remain, and a woman can enjoy intercourse as much as she did before menopause.