Uterus

Overview

The uterus lies between bladder and rectum, with a body above a narrower cervix. Its endometrium changes through the reproductive cycle, and its myometrium expands during pregnancy and contracts during birth. Forward tilt and flexion are common, but uterine position varies normally with anatomy, bladder filling and reproductive history.

Reference facts

Location

It occupies the central pelvis posterior to the bladder and anterior to the rectum; anterior and posterior peritoneal reflections form the vesicouterine and rectouterine pouches.

Parts

The fundus lies above the tubal openings, the body contains the main cavity, and an isthmus connects to the cervix. The isthmic region contributes to the lower uterine segment during pregnancy.

Blood supply

Uterine arteries supply most of the organ and join ovarian branches near the horns. Intramural branches distribute blood through the muscle and endometrial layers.

Innervation

The uterovaginal plexus contains sympathetic and sacral parasympathetic pathways. First-stage labor pain from uterine contractions and cervical dilation is transmitted mainly to T10–L1; later vaginal and perineal pain also involves sacral somatic pathways.

Venous/Lymphatic drainage

Uterine veins enter pelvic venous plexuses and the internal iliac veins. Lymph follows overlapping routes to pelvic and lumbar nodes, with a smaller fundal pathway accompanying the round ligament toward the groin.

Relations

The body commonly overlies the bladder. Tubes and ovarian and round ligaments meet near the horns; ureters and uterine vessels lie laterally near the cervix, with rectouterine peritoneum behind.

Function

The endometrium supports implantation and participates in menstruation. During pregnancy the uterus accommodates the developing fetus and placenta, then myometrial contractions contribute to delivery.

Frequently asked questions