The Uterus.—Of all the organs, the womb suffers the greatest changes, (both in body and cervix) in volume, form, consistency, situation, direc tion, relations, intimate (histological) structure, physical and pliysiologi cal properties and functions.
I. Body of the Uterus.
1st. Changes in Volume.—Even during menstruation the uterus so in creases that it rises above the superior border of the pubes on account of - catamenial congestion, and can easily be felt on abdominal palpation. Pregnancy increases it still more, but always at the expense of the body and fundus. The cervix is scarcely affected at all. This increase, al tinguish the uterine from the abdominal walls. These characteristics, by allowing the foetus free movement, prevent abnormal positions and presentations.
5th. Situation and Direction.—The change in situation varies in differ ent women, and at different periods of pregnancy. During the first months of gestation the uterus, from pressure of the intestines, and from increase in its own weight, sinks down into the pelvis. In some women, however, the fundus rises above the pubes within the first few weeks of pregnancy. At the third month, it is too large for the pelvis, rising above the superior strait, finally filling all the abdominal cavity, reaching the diaphragm, and diminishing the vertical diameter of the thorax. At the same time the sacro-vertebral angle, and the curvature of the spine, throw the uterus from the axis of the superior strait, and bend it to one side or the other. The uterus usually bends to the right; the reason for this is yet unknown.
Levret thought it was caused by the insertion of the placenta; Desor meaux, by the sigmoid flexure; others thought it to be caused by the greater use of the right arm and by right lateral decubitus; Madame Boivin by the shortness of the right round ligament.
Dubois states that the cacum on the right would compensate for the sigmoid flexure. Velpeau proved Desormoaux to have made an anatomi cal error by giving to the mesentery a direction from above downward, and from right to left. In left-handed women the uterus inclines to the right in spite of the arm that is chiefly used. Pajot measured the round ligaments and did not find the left one longer than the right, except in a few cases.
Rotation.---While undergoing inclination the uterus also, (during the last months of pregnancy), rotates on its axis, the anterior surface turn ing to the right, thus bringing the left lateral wall anteriorly.
This rotation, rudimentary in women, is well-marked in some animals, the womb revolving completely on its axis, twisting the vagina on itself, and thus arises an impassable barrier to delivery.
6th. Relations of the Uterus at Term.—The upper three-fourths of the anterior surface of the uterus rests against the internal abdominal wall, from which it is separated by the omentum or intestinal folds. Below, it. touches the posterior surface of the bladder; the extent of this relation depends on the amount of fluid in the bladder. Posteriorly, it is in re lation with the rectum, sacrum and its promontory, the iliac vessels and the first branches of the sacral nerves. Above the promontory, the uterus touches the mesentery, the intestine (which often separates it from the aorta), the inferior c,ava, the ureters, the columns and the posterior sur face of the diaphragm.
The fundus is in relation with the anterior abdominal wall, transverse colon, anterior border of the liver, greater curvature of the stomach and the diaphragm, from which it is separated by the organs named.
The right lateral border is in.relation with the external and internal iliac vessels, obturator vessels and nerves, the psoas and iliacus muscles, mecum, ascending colon and the abdominal wall. The left border is in relation with the iliac vessels, the obturator vessels and nerves, the psoas and dawns, the sigmoid flexure, the descending colon, and folds of intes tine pushed" over by the right obliquity of the uterus.
Below, the inferior segment of the uterus and the cervix project into the vagina. The bladder is in front, the rectum behind.
IIence, Pajot states, the uterus rests on the anterior wall of the abdo men, which forms for it an elastic and supple plane, preventing shocks to the fcetns from walking, movement, etc. This also explains the part played by the abdominal wall in the last momenta of delivery.