The antero-posterior diameter of the uterus is greatest about the centre of the body, where it measures in the nulliparous organ 11"'-12"'.
Weight. — The weight of the adult virgin uterus, deprived of' the appendages, is 9-12 drachms.
Regional divisions.— The uterus is divided primarily into a body and neck or cervix. Each of these is again subdivided, the upper portion of the body being termed the fundus, while the lower or terminal part of the neck is distinguished as its vaginal portion. These divisions, though to a certain extent artificial, are necessary, not only to facilitate descrip tion, but also to distinguish parts which ex hibit great and important differences both of structure and function. So great, indeed, is the amount of structural and functional dif ference between the body and neck of the womb, as almost to justify these being re garded as two distinct organs.
The fundus is that portion of the body of the uterus which lies above an imaginary line, (fig. 421. A A,) drawn transversely across the organ from the point of attachment of one Fallopian tube to that of the opposite side. This portion of the uterus is of a very dense and firm texture. It is very slightly convex in the virgin state, but becomes considerably arched and expanded during pregnancy, when it forms, as it were, a vaulted roof to the organ. After parturition the fundus does not regain its former figure, but retains more or less of the rounded form which constitutes one of the points of difference between the nulliparous and multiparous organ. The fundus is that part of the uterus which, from its concealed position within the pelvis in the unimpreanated healthy state, is the least ca pable ofbbeing examined during life. It is of all parts of the uterus that which is the least subject to destructive disorganisation by malignant growths, frequently remaining un altered in texture after the whole of the vix has been destroyed by carcinomatous ulceration. On the other hand it is the part inner surfaces are not in immediate contact like those of the uterine body ; but diverge slightly to enclose a flattened spindle-shaped cavity, termed the canal or cavity of the cervix.
The situation of the widest or central part of this canal is indicated by an external late ral bulging of the walls of the uterine neck. The posterior part of the cervix receives a loose investment of peritoneum ; but the whole or the greater portion of its anterior wall, as well as the lower or vaginal portion, is uninvested by that membrane.
The vaginal lower extremity of the cervix (fik. 424. below, c c) projects from which polypi, that are not cervical in their ori:tin, most frequently arise ; and it is very cominonly the seat of those large hyper tropbic growths of the uterine tissue, which are usually termed fibrous tumours. The
fundus is also the part to which the upper portion of the placenta is most frequently attached.
The body is included between the line above indicated, and another, B B, drawn through the narrowest part of the organ, or that point at which the tapering lateral walls of the uterus approximate in the greatest de gree before they again diverge to pass into the cervix. The body of the uterus consti tutes its principal portion. It is that part which, more than any other, expands to in vest the ovum. It is freely supplied with blood-vessels, which, entering by the lateral border, ramify abundantly through the ante rior and posterior malls. These walls are usually half an inch in thickness. They are separated from each other by a scarcely appre. ciable cavity, to be hereafter described, lying between the inner surfaces of the parietes. The extreme narrowness of this cavity is shown in fzga. 427 — 430., which represent transverse sections of the uterine body, at various points between the fundus and in ternal os.
The cervix, or neck, (fig. 424. B-C), is a cylindriform prolong,ation of the uterine body, to which it serves as an excretory conduit. It is composed in part of tissues similar to those of the body, hut the arrangement of these is materially different. The walls of the cervix measure 4"/ in average thickness. Their into the vag,ina in the form of a flattened cone. The length of this conical projection is about 4m. It is of unequal diameter. Transversely it measures 11"-12"' at the base, and 6'"- 7"' at the apex ; but its antero-posterior dia meters are only 7m-8"' at the base, and 5'" at the apex ; so that a section of this part will represent an ellipse. Around the base of this conical portion the walls of the upper end of the vagina are attached. The vaginal attachment constitutes the line of demarcation between the lower or vaginal and the upper or supra vaginal division of the cervix. It should be observed that the end of the cervix does not lie, as is commonly supposed, exactly at the extremity of the vaginal canal, but that it projects into its upper wall, so that the upper vaginal wall is shorter than the lower by the whole antero-posterior diameter of the cervix (fig. 426. and 433.). This explains the diffi culty which is sometimes experienced in bringing the cervix into view when a tubular speculum is employed, the sides of which are all of equal length. There can be no doubt that this peculiar position of the extremity of the cervix prevents the part from suffering injury in coitu, because the impulse of the intromittent organ is received upon the end of the vagina, and is distributed upon the adjacent parts, through the intervention es pecially of the utero-sacral ligaments. See further, p. 689.