A Text-book of Diseases of Women

by Charles B. Penrose

The uterus does not surmount the vagina with the axes of the two structures in the same line, as is shown in some anatomical plates.

The cervix looks backward toward the coccyx, from the tip of which it is situated 0.6 to 1.2 inches.

The uterus is maintained in position by a variety of factors. The ligaments, which have been described, are eight in number—broad ligaments, round ligaments, utero-sacral and utero-vesical ligaments.

With the exception of the round ligaments, which are muscular structures, the uterine ligaments are formed by peritoneal folds, including connective tissue, blood-vessels, lymphatics, and a small amount of unstriped muscle.

When the woman is erect the insertions and origins of the various uterine ligaments lie in the same horizontal plane. The insertion of no ligament is higher than its origin in the uterus; therefore these ligaments do not act as suspensory ligaments when the uterus is in its normal position. The truth of this fact is repeatedly demonstrated at operations. If the cervix be caught with a tenaculum when the woman is on her back, the uterus may, with but very little force, be drawn downward toward the ostium vaginæ to the extent of one or two inches; and similarly, by a slight digital pressure on the cervix, the uterus may be pushed upward from one to two inches above its normal position.

The ligaments of the uterus act as guys. They steady it, and prevent too great lateral and fore-and-aft movement; they do not, when the uterus is in its normal position or at its normal level, sustain it against the force of gravity. When, however, the uterus, for any reason, falls an inch or more below its normal level, the uterine ligaments become suspensory in character.

In the normal woman the vagina is always closed. As has already been said, it is a slit in the pelvic floor, valvular in character; consequently the abdominal and pelvic viscera may be considered to be contained in a closed vessel, in woman as well as in man. The uterus floats in this closed vessel at a level which is consistent with its own specific gravity. If, for any reason, the specific gravity of the uterus were increased, it would sink below the level at which it is normally situated.

Since, normally, there is no tendency in the uterus to change its position, the pressure upon it must be equal in all directions. The subject may perhaps be better understood by referring to a few simple facts in hydrostatics. If a fluid contained in a closed vessel be in a condition of equilibrium so that its various particles are at rest, then the pressure upon any particle is equal and opposite in all directions ([Fig. 63]); otherwise the particles would not be in equilibrium, but would move. The bottom of such a vessel, however, is not, like the particles of the fluid, surrounded on all sides by the fluid, but above it is the fluid, and below it is the atmospheric air. Any point upon the bottom of the vessel is subjected to a downward pressure equal to the weight of the column of fluid above the point; this downward pressure is resisted by the strength of the material composing the vessel. If this material be yielding or elastic in character, the pressure above will make the bottom protrude to a certain extent. A particle within the fluid (like X immediately above the bottom of the vessel) will be subjected to a downward pressure equal to the weight of the column of fluid above it; but this pressure will be counterbalanced not by any strength in the particle, but by a counter-force acting from below equal and opposite to that acting from above.

Fig. 63.—Vessel containing fluid in equilibrium. The arrows indicate the direction of the pressure at various points.