UTERUS (Lat., womb), or WOMB. A flat tened, pear-shaped organ, lying behind the sym physis of the pubes in the female human being, and constituting her principal generative organ. It consists of a body, a base or fundus, a neck or cervix, and a mouth. It lies in the line of the axis of the outlet of the pelvis (q.v.), with base directed upward and forward, and the neck di rected slightly backward. In the unimpregnated condition it is about three inches in length, two in breadth, and one in thickness. On laying it open, or exploring its interior by the introduction of an instrument through the os uteri, its cavity is found to be very narrow, and to contain a lit tle mucus. Its walls are nearly half an inch thick, and are mainly composed of muscle fibres running irregularly in all directions except round the os, where they make a partial sphincter. This muscular coat, which constitutes the bulk of the organ, is covered externally with a serous coat, derived from the peritoneum, and is lined internally by a mucous coat continuous with that of the canal called the vagina, by which the interior of the womb communicates with the outer surface of the body. The neck or cervix of the womb is distinguished from the body by a well-marked construction. The mouth, or os, projects slightly into the vagina. This opening is nearly round in the virgin, and transverse after parturition. It is of considerable size, and is named the os uteri eXtCrI211111 ; it leads into a nar row canal which terminates at the upper end of the cervix in a smaller opening, the os internam, beyond which is the shallow triangular cavity of the womb, of which it forms the lower angle, while the two upper angles, which are funnel shaped, constitute the beginning of the Fallopian tubes, or oviducts, whose apertures are so small as only to admit the passage of a fine bristle.
The blood-vessels and nerves enlarge in a very remarkable way during pregnancy, so as to adapt themselves to the increased wants of the organ, which at the ninth month of utero-gestation weighs from two to four pounds. The name appendages to the uterus or adnexa is given to the Fallopian tubes and ovaries, which are inclosed by the lateral folds of the peritoneum called the broad ligaments. The uterus is suspended in the pelvic cavity in such a way as, by its mo bility, to escape concussion from without or dis turbance from the varying conditions of the sur rounding viscera, while at the same time to allow of its vastly increasing in bulk with com paratively little discomfort when pregnancy occurs. This is effected by several reduplica tions of peritoneum, containing variable quan tities of fibrous and muscular tissue, and known from their form or connection as the broad, the round, the '0cm-sacra1, and the utero-tiesieal ligaments. During pregnancy the uterus in creases gradually to the end of the ninth month, when it contracts and expels the fcetus. The organ then atrophies, contracts, and resumes nearly its initial size and shape.
The chief functions of the uterus relate to menstruation (q.v.). insemination, gestation, and parturition. See EMBRYOLOGY; ECETUS; OBSTET RICS; OVARY; STERILITY; UTERUS, DISEASES 01' THE.