(ū′tĕr-ŭs)
[Pronunciation]
[L.]

A reproductive organ for containing and nourishing the embryo and fetus from the time the fertilized egg is implanted to the time the fetus is born.

SYN: womb

Figure: UTERUS
Uterus and its ligaments seen laparoscopically (×1/3)



See: genitalia, female

ANATOMY
The uterus is a muscular, hollow, pear-shaped organ situated in the midpelvis between the sacrum and the pubic symphysis. Before child-bearing, it is about 3 in. (7.5 cm) long, 2 in. (5 cm) wide, and 1 in. ( 2.5 cm) thick. Its upper surface is covered by peritoneum called the perimetrium, and it is supported by the pelvic diaphragm supplemented by the two broad ligaments, two round ligaments, and two uterosacral ligaments. It is usually anteflexed, or tilted forward, over the top of the urinary bladder. The upper portion of the uterus, between the openings of the fallopian tubes, is the fundus; the large central portion is the body; and the narrow lower end is the cervix, which projects into the vagina. The cavity of the uterus is widest in the fundus. The canal of the cervix is narrow, opens into the uterine cavity at the internal os, and into the vagina at the external os.

The wall of the uterus consists of the outer perimetrium, middle myometrium, and inner endometrium. The perimetrium is the visceral peritoneum that covers the uterus, except for the portion that rests on the bladder and the vaginal part of the cervix. The thick myometrium is smooth muscle that contracts for labor and delivery. The endometrium is the vascular lining that can become the placenta for nourishment of the embryo-fetus; it is thin before puberty; grows and is shed cyclically during childbearing years, and degenerates after menopause. The uterine and ovarian arteries supply blood to the uterus.

POSITIONS
Anteflexion: The uterus bends forward. Anteversion: The fundus is displaced forward toward the pubis, while the cervix is tilted up toward the sacrum. Retroflexion: The uterus bends backward at the junction of the body and the cervix. Retroversion: The uterus inclines backward with retention of the normal curve; this position is the opposite of anteversion.

See: hysterectomy; pregnancy

Subentries:
uterus acollis
uterus arcuatus
uterus bicornis
uterus biforis
uterus bilocularis
bipartite uterus
cancer of uterus
uterus cordiformis
uterus didelphys
uterus duplex
fetal uterus
fibroids of uterus
gravid uterus
uterus masculinus
uterus parvicollis
prolapse of uterus
pubescent uterus
rupture of uterus in pregnancy
subinvolution of uterus
tumors of uterus
uterus unicornis