thf: uterus 1047 



Variations in form according to age. — Jn young cliildrcn the l)ody is but 

 slightly developed in proportion to the cervix, and the i)roniinence of the intra- 

 vaginal segment is relatively great. In the virgin uterus ol a young adult the 

 knigtli is al)out equally divided between body and cervix, but after childlnrth the 

 body never returns to its original size, and its length Avhen involution is complete 

 is nearly double that of the neck. In old age the entire organ undergoes atrophy. 



The cavity of the uterus is reduced to a fissure b}' the antero-posterior llattening 

 of the walls. It is divisible into two segm(uits, that of the body and that of the 

 neck. The shai)e of the cavity of the body is that of a triangle with convex sides 

 (in the virgin) and three open angles. At the two superior angles are the orifices 

 of the oviducts, and the lower angle presents the os uteri internum or a])erture 

 of coinmunication with the neck. The walls are smooth, and moistened with 

 mucus. 



The average length of the cavity in the nulliparous adult is about two inches 

 (5 cm.); in multipara?, two and a quarter to two and a half inches (5 '5 to 6 cm,). 

 The greatest transverse diameter is a little less than half of these measurements. 



The cavity of the neck is fusiform, terminating in the os internum al)Ove, and 

 in the os externum below. The sui)erior opening is circular, the inferior usually 

 in the form of a transverse fissure. The mucous lining of the anterior and j)osterior 

 walls })resents ridges which bear some resemljlance to those of the vagina, Init are 

 dependent u])on the arrangement of the innermost layers of the muscular wall, and 

 not upon a sim])le plication of the mucous membrane. The whole length of each 

 wall is traversed by a longitudinal nearly median ridge or stem, from which pass 

 a number of branches in an outward and slightly upward direction. The 

 figure formed by these folds is designated by the name of arbor vitse uterina ; it is 

 most marked in the young, and tends to effacement after repeated parturitions. 

 The cavity usually contains a plug of alkaline mucus. 



Structure. — The uterus is composed of three coats — an outer sero- fibrous, a 

 middle muscular, and an inner mucous. The serous membrane covers the upper 

 half or two-thirds of the anterior surface, the Avhole of the supravaginal portion of 

 the posterior surface, and the summit. The lower portion of the anterior wall is 

 separated from the bladder by cellular tissue continuous with the subperitoneal 

 fascia, and a thin layer of the same structure may be demonstrated over the lower 

 part of the posterior surface and laterally into the base of the broad ligament on 

 either side between the two peritoneal lamina?. Owing to this dis])Osition of the suV)- 

 serous tissue, the whole of the cervix uteri may be amputated without encroaching 

 upon the peritoneal cavity. 



The muscular coat constitutes the greater part of the thickness of the organ. 

 The arrangement of the fibres is very com])lex, but a fairly satisfactory division 

 into three layers may be demonstrated: — a thin outer layer, partly longitudinal, 

 l)artly transverse in direction, continuous with the muscular fibres of the oviducts, 

 vagina, round, ovarian, and utero-sacral ligaments, and with the nmscular expan- 

 sion in the broad ligaments; a middle layer, very thick, its fibres plexiform, run- 

 ning in all directions, and intermingled with large venous plexuses in the body of 

 the uterus, the innermost strands forming s])hincteric rings around the os internum 

 and around the orifices of the oviducts; and a thin internal layer, longitudinal in 

 the l)ody, and ]trodu(itig the ridges of the arlx)r vitic in the cervix. 



The mucous membrane of the body is smooth and pale, lined with cylindrical 

 ciliated ei)itiielium, and pierced by innumerable tubular glands. The ciliary motion 

 is from within outwards. The mucous membrane of the cavity of the Dcrk is 

 thicker and is plicated in the maimer already described; its epithelium is ciliated 

 down to the external opening, but there undergoes a transition into the squamous 

 laminated epithelium which covers the intravaginal jiortion of the os. Many tubu- 

 lar and racemose mucous glands open into the furrows of the arbor vitre. and these 

 are lialtle to pathological changes which cause them to assume a vesicular charac- 

 ter, when tlu'v are sometimes known under the fanciful name of ovula Nabothi. 



Ligaments. — The so-called ligaments of the uterus are of two kinds, ])eritoneal 

 and nniscular. 



The peritoneal ligaments are six in numlter: two lateral, two anterior, and two 

 posterior. 



