4Qfi THE UTERUS. 



Nerves.— The distribution of the nerves has been previously described. They 

 are derived fi-om the inferior hypogastric plexuses, the spermatic plexuses, and 

 the third and fourth sacral nerves. They consist of both medullated and plain 

 fibres ; they are in greatest number in the neck, where they run into the papillce 

 of the mucous membrane. 



In animals small ganglia have been observed in the submucous tissue con- 

 nected with the plain fibres. According- to Frankenhauser. the dark bordered 

 fibres rmi into the muscles. di\ading into plain fibres before they form bulbs, and 

 are at last traceable into the nuclei of the muscular cell-filores (Chrobak, in 

 Strieker's Handbuch, and Frankenhiiuser, Die Kerven der Gebaermutter, &c., 

 Jena, 1867). The nerves, especially the dark bordered fibres increase con- 

 siderably during pregnancy. 



Periodic structural chang-es in the Tlterus. — The changes which accom- 

 pany menstruation and gestation may be shortly indicated here. 



Accordi^ig to the observations of J. Williams, already quoted, which confirm 

 and greatly extend those of previous inquirers, it appears that at each successive 

 recurrence of iiii'ii.stniation a complete removal of the glandular part of the 

 mucous membrane takes place by a process of softening and molecular disuitegi-a- 

 tion which commences, along with the menstrual discharge, close to the cervix, 

 or at the os internum, and advances progressively towards the fundus dui-ing the 

 remaining days of the flow of blood. Previous to this periodic change, in addi- 

 tion to gi-eatly increased general vascularity of the parts, the mucous membrane 

 becomes very much thicker, attaining a diameter of a fifth or even a quarter of 

 an inch, and the utricular glands are proportionally enlarged. The process of 

 disintegration reaches as far as the inner muscular fibres which rtm between the 

 deepest parts of the glands ; and as the smaller blood-ves?els are similarly 

 affected, the hemorrhage is the dii'ect result of their destruction and open 

 condition. 



The process of restoration of the uterine membrane and its glands, which i& 

 effected in the interval, and which begins even before the cessation of the 

 menstrual flow, proceeds in the same order from the lower end upwards to the 

 fundus of the cavity, and consists in a very rapid proliferation of the cells and 

 nuclei which occupy the interstices of the inner muscular fibres, and among 

 which are probably embedded the deepest parts of the utricidar glands. The 

 lining membrane of the cer\-ix does not participate in the changes now 

 referred to. 



In (ic^tafion more extensive alterations ensue, which necessarily affect the size, 

 shape, and position of the uterus, the thickness and amount of substance in its 

 walls, the dimensions and form of its cp.vity, and the character of its cervis 

 and of its os externum and os internum. Its weight increases from about one 

 oimce to a pound and a half or even three pounds. Its colour becomes darker, 

 its tissue less dense, its muscular bundles more evident, and the fibres more devel= 

 oped. A very great increase takes place in the muscular tissue, and this increase 

 is the result not only of the enlargement of already existing elements, the fibre- 

 cells becoming enlarged to the extent of from seven to eleven times in length, 

 and from two to five times in breadth (Kolliker), but also of new formation. The 

 increase in length and thickness is general ; the new formation occra-s mainly in 

 the innermost layei-s. and continues until the sixth month of pregnancy, when it 

 ceases. The round ligaments become enlarged, and their muscular structm-e 

 more marked; the broad ligaments are encroached upon by the intrusion 

 of the growing utcnis between their layers, The mucous membrane and 

 the glands of the body of the uterus undergo an enlargement very similar to 

 that which precedes menstruation, and they subsequently become the seat of 

 peculiar changes, which lead to the formation of the decidual membrane, to be 

 more pai-ticularly stated under Development ; whilst the membrane of the cervis 

 loses its columns and laigre. The blood-vessels and lymphatics are gi-eatly en- 

 larged, and it is observed that the aiteries become exceedingly tortuous as they 

 ramify upon the organ. The neiwes, as stated above, undergo also considerable 

 enlargement. 



After parturition, the uterus gi-adually but rapidly diminishes till it regains tlis 



