The cavity of the uterus is most contracted at the point where the cervix is united to the body, which here forms the _os uteri internum_; from this point the cervix gradually dilates as far as its middle portion, when it again contracts; its lower extremity terminates in the upper part of the vagina by an anterior and posterior cushion-like projection, of which the posterior is usually the longest, although from the direction of the uterine axis the anterior is commonly felt lowest in the pelvis. Between these there is a transverse fissure known by the name of _os tincæ_ or _os uteri externum_, the lips or labia of which are formed by the two above-mentioned prominences. The internal surface of the body of the uterus is smooth, whereas that of the cervix is uneven, forming upon its anterior and posterior wall a number of delicate rugæ diverging obliquely in an arborescent form, and hence called the _arbor vitæ_. The lips of the os uteri are smooth, except when slight lacerations have taken place during labour. In the virgin state the uterus is about two inches long, of which the cervix occupies the smaller half: the greatest breadth of the body is sixteen lines; that of the cervix from nine to ten. The uterus which has been impregnated, especially when this has been frequently the case, scarcely ever regains its original dimensions, and the fissure which the os tincæ forms becomes broader from before backwards. The weight of an adult virgin uterus is from seven to eight drachms, but the uterus which has been once impregnated is seldom less than an ounce and a half. It lies between the bladder and rectum, its upper half being covered by peritoneum, which closely adheres to it. In the adult state it is situated entirely in the cavity of the pelvis; the fundus, which is below the upper edge of the symphysis pubis, is turned forwards and upwards, while its mouth is directed downwards and backwards, so that its long axis is nearly parallel to the axis of the superior aperture of the pelvis. The uterus is connected to the neighbouring parts by several duplicatures of peritoneum, which are continuous with that portion of it which covers the fundus. The most considerable are the _broad_ or _lateral ligaments_: these arise from the sides of the uterus, which is enclosed between their anterior and posterior layers or laminæ; they proceed transversely outwards towards the sides of the pelvic cavity, which is thus divided into two portions, and are then continued into that portion of the peritoneum which lines the cavity.