Uterus
The uterus is a vital reproductive organ located in the pelvis, serving as the site for fetal development during pregnancy. It is a bulb-shaped pouch, approximately 3 inches in length, with a muscular wall that is supported by ligaments. The uterus consists of two primary sections: the body (corpus), which is situated above the fallopian tubes, and the cervix, which connects the uterus to the vagina and plays a crucial role during ovulation, menstruation, and childbirth. The thick muscle layer, known as the myometrium, is lined with a mucous membrane called the endometrium, which undergoes changes throughout a woman’s reproductive cycle.
Various disorders can affect the uterus, including noncancerous growths such as fibroids and conditions like adenomyosis and endometriosis, which can lead to significant discomfort and irregular bleeding. Additionally, the uterus can experience issues such as abnormal bleeding, vaginitis, and prolapse, where it sagging into the vagina due to pregnancy or childbirth. Two common types of cancer associated with the uterus include endometrial cancer, which arises from the lining of the uterus, and cervical cancer, often linked to human papillomavirus infection. Both types of cancer have a greater chance of successful treatment when detected early. Understanding the structure and functions of the uterus is essential for recognizing its role in women's health and reproductive processes.
Subject Terms
Uterus
Also known as: Womb
Anatomy or system affected: Genitals, reproductive system
Definition: The organ, located in the pelvis of the female, in which a fetus develops after conception
Structure and Functions
The uterus provides a space for a fetus to grow. Situated in the pelvis, in front of the rectum and behind the bladder, the uterus is a bulb-shaped pouch about 3 inches (8 centimeters) in length that has heavily muscled walls and is held firmly in place by several ligaments. The uterus has two main parts: the body (corpus) includes the area above the opening to the two fallopian tubes, while the fundus is the larger area below the fallopian tubes to the cervix, all positioned at about a ninety-degree angle to the vagina; the cervix is a funnel that connects the body to the vagina. During a woman’s reproductive years, the body is about double the size of the cervix, but that proportion reverses after menopause. The thick muscle (myometrium) of the uterus is lined with mucous membrane, the endometrium.
During ovulation, sperm can enter the body through the cervix on its way to fertilize an egg in a fallopian tube. During menstruation, blood and excess endometrium exit the uterus through the cervix. During gestation, the uterus expands to accommodate the growth of the fetus, and during labor, the walls contract to expel the fetus through the cervix and vagina.
Disorders and Diseases
Among common disorders specific to the uterus are various noncancerous growths. Fibroids are masses of muscle and fibrous tissue, of unknown cause, in the uterine wall that occur in about 20 percent of women more than thirty-five years old. If small, they are seldom noticed, but large fibroids can affect urination and menstruation and cause pain. Adenomyosis involves enlargement of the uterus after glandular tissue obtrudes into the myometrium; it can result in heavy, painful periods, sensations of pressure, and bleeding between periods. Endometriosis occurs when bits of the endometrium grow outside the uterus, which may produce pain in the lower abdomen or pelvis. The uterus is also subject to abnormal bleeding and vaginitis, inflammation caused by chemical irritants, bacteria, or yeast (candidiasis). Sometimes, because of pregnancy or birth, the uterus sags and protrudes into the vagina, a condition known as prolapsed uterus.
Two cancers in the uterus are among the most common to afflict women. Endometrial cancer grows in the membrane lining the body. It usually develops between the ages of fifty and sixty and has a high cure rate if detected early. Cervical cancer usually develops between the ages of thirty-five and fifty-five, following infection by the human papillomavirus, and is also curable if detected early. Untreated, both penetrate the uterine wall and spread to nearby organs.
Bibliography
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Fortner, Kimberley B., ed. The Johns Hopkins Manual of Gynecology and Obstetrics. 6th ed. Wolters Kluwer, 2021.
Parker, Steve. The Human Body Book. Revised ed. DK Adult, 2019.
Thibodeau, Gary A., and Kevin T. Patton. Structure and Function of the Body. 14th ed. Mosby/Elsevier, 2012.
"Uterine Diseases." MedlinePlus, medlineplus.gov/uterinediseases.html. Accessed 15 July 2023.