The apertures by which the Fallopiah tubes enter the upper angles of the uterus are so small as only to admit of the passage ofa fine bristle (fig. 406.). That by which the cavity of the body communicates at its inferior angle with the canal of the cervix has an average diameter of li"/-3"'. This orifice is the os uteri interntim (fig. 431. i).
The following are the dimensions of the ute rine cavity :—Iength I 1"'-12'" ; breadth be tween the points of' entrance of the Fallopian tubes 11"'-12"' ; at the centre of the ca vity 4"' ; at the os internum The cavity of the cervix consists of a flat tened fusiform canal running through the centre of the uterine neck. The widest por tion occurs about the middle, where the canal measures transversely 3I"' —6'" Cfig. 431. c c), whilst towards either extremity the parietes gradually approximate so as to leave a narrow aperture at each end ; the superior aperture being the orifice already described as the os uteri internam, the dimensions of which have been given;—the inferior being the os externum, or os tincw, which measures 3"1-4'" in transverse diameter. The antero posterior diameter of the canal at its widest part is not more than The en tire length of the cervical cavity is 12"' —13"'.
The mucous membrane lining this cavity is probably not greatly inferior in extent to that of the uterine body. But on account of the smaller space in which it is contained, instead of forming an even layer, the mem brane is here thrown into numerous folds or plicw, having intermediate furrows, often traversed by lesser phew, which extend the secreting surface, and furnish a more consi derable seat for those numerous mucous crypts which abound upon almost every por tion of this structure.
The forms which the cervical folds or plicm assume are sufficiently remarkable to have attracted the attention of anatomists at all periods. They are, however, so variable, that if twenty specimens be cornpared to gether, scarcely two will be found to present precisely the same arrangement. On this account it is difficult to furnish any descrip tion of them which shall be universally appli cable.
Nevertheless, two forms appear to me to he more prevalent than others. In one a single prominent raphe occupies the centre of each wall of the cervix. (Fig. 431. c c.) C9111•• mencing sometitnes at a distance of I f"'-3'" above the margin of the uterine lip and ex tending upwards either centrally or to one side of the median line, and reaching as far as the internal os, it terminates here in a bulbous expansion, or branches out into numerous small ramifications. From either side of this
median perpendicular fold are given off lateral Om, varying in number, but being usually not less than 6-9. These soon bifurcate once or twice, so that the number of folds will vary considerably, according as they are counted immediately at, or at some distance from, their line of junction in the central raphe. The uppermost pair of lateral plicx,or those next to the raphe, often exhibit the same bulbous extremity; and these together fill the upper or narrowest portion of the cer vical canal. Lower down, where the canal be comes wider, the lateral plicze spread out on either side of the central raphe, the upper ones in an oblique, the middle and lower ones in a more horizontal direction. These soon bifurcate, and form a series of oblique, hori zontal, or arched laminx, whose arrangement varies much according to the fulness of the folds, the depth of the furrows between them, and the distance by which the laminm are se parated. If the latter are prominent and very closely set, their margins may' overlie each other, iike the branchial lamin of a fish, so that no intermediate furrows are perceptible ; or the folds, not being very prominent, may merely' lie in apposition, leaving no visibie in terspace until they are drawn asunder ; but when the plicx are less full and prominent a furrow is perceptible between each. These furrows of necessity take the same direction as the plicw by w hich they are bounded.
In another common form which the plicm assume, the general lines of folds and interme diate furrows take a more vertical direction, so that sometimes as many as six or eight of the more central lamitim may be traced run ning down side by side to the very margin of the cervical lips ( fig. 424.). Here often the two most central folds appear to run up from one end to the other of the cervical canal ; but still commonly one of these is more fully developed than the rest ; its upper bulbous extremity- occupying the position in the narrow portion of the cervical canal. al ready described, m bile its lateral divisions being more numerous than those of the plicx next adjoining, it takes the office of a raphe, though its position may be, as it often is, more or less eccentric.