The uterus or womb is also situated between the bladder and the rectum, but above the vagina. Such is its shape that it has been compared to a pear with a long neck. There is, of course, considerable difference between the body and the neck, the first being twice as broad as the last. Each of these parts is somewhat flattened. In subjects of mature age, who have been pregnant, the whole of the uterus is about two inches and a half in length, and more than an inch and a half in breadth at the broadest part of the body. It is near an inch in thickness. The neck of the uterus is situated downward, and may be said to be inserted into the upper extremity of the vagina. It extends down into the vagina the better part of an inch. In the uterus is a cavity which approaches the triangular form, and from which a canal passes down through the neck of the uterus into the vagina. This cavity is so small that its sides are almost in contact So that the uterus is a thick, firm organ for so small a one. Comparing the cavity of the uterus to a triangle, we say the upper side or line of this triangle is transverse with respect to the body, and the other two lines pass downward and inward, so that they would form an angle below, did they not before they meet take a turn more directly downward to form the canal just mentioned. In each of the upper angles there is an orifice of such size as to admit of a hog's bristle. These little orifices are the mouths of two tubes, called the Fallopian tubes, of which more will be said presently. The canal which passes through the neck of the uterus, connecting the cavity of this organ with that of the vagina, is about a quarter of an inch in diameter. It is different from other ducts, for it seems to be a part of the cavity from which it extends, inasmuch as when the cavity of the uterus is enlarged in the progress of pregnancy, this canal is gradually converted into a part of that cavity. The lower extremity of the neck of the uterus is irregularly convex and tumid. The orifice of the canal in it is oval, and so situated that it divides the convex surface of the lower extremity of the neck in two portions, which are called the lips of the uterus. The anterior is thicker than the posterior. The orifice itself is called _os tincae_ or _os uteri_, or in English, the mouth of the womb. When the parts are in a weak, relaxed state, the mouth or neck of the uterus is quite low, and in almost all oases it may be reached by a finger introduced into the vagina, especially by a second person, who carries the hand behind.