The full rectum forces the uterus in the opposite direction, toward the symphysis, and thereby counteracts the influence of the bladder. This anterior movement is, however, somewhat limited, and is confined to the cervical portion, except when the body has been forced back into close proximity with the rectum by the over-distended bladder.
Normal Supports of the Uterus.
The uterus is maintained in its normal position and location by the following agents:
a. The uterine ligaments;
b. The pelvic floor.3
3 For a description of the female pelvic floor see Hart's Atlas.
a. Physiologically, these ligaments are relaxed; the state of tension would be pathological; they do not fix the uterus; they only tend to limit its movements to their normal range. Backward displacement of the body is resisted by the round ligaments, backward displacement of the cervix by the utero-vesical ligaments and by the vesico-vaginal wall. Forward and downward displacements are resisted by the utero-sacral ligaments, and excessive lateral motion by the broad ligaments. This restraining power is doubtless greater in the utero-sacral than in any of the other ligaments.
b. The pelvic floor, which is the chief support of the uterus, is divided into two segments, the pubic and the sacral. The pubic segment4 is composed of bladder, urethra, anterior vaginal wall, and bladder peritoneum. It is attached in front to the symphysis pubis and laterally to the anterior bony walls of the pelvis. The sacral segment5 is composed of rectum, perineum, posterior vaginal wall, and strong tendinous and muscular tissue. It is attached to the coccyx, to the sacrum, and to the posterior wall of the bony pelvis.
4 Hart and Barbour's Manual of Gynecology.