26 Veterinary Obstetrics 



where they serve specially as occlusive agents to establish a sep- 

 aration of the uterine from the vaginal cavity. 



The peritoneal layer of the uterus is derived from that of the 

 abdominal walls and completely envelops the organ except at the 

 points of continuity with the oviducts and vagina and the inter- 

 stice between the two peritoneal sheets of the broad ligament at 

 their points of uterine attachment. The broad ligaments have 

 already been described on page 21. 



Those portions of the Muellerian ducts from which the uterus- 

 is later developed are formed early in embryonic life behind the 

 peritoneum and later leave the abdominal walls, to float freely 

 within the abdominal cavity, suspended by the broad ligaments- 

 or, in the gravid state, to rest upon the abdominal floor. 



The uterus is further retained in position by its continuity 

 anteriorly with the oviducts and posteriorly with the vagina. 

 The round ligament of the uterus, arising from the skin ordartos 

 in the region normally constituting the fundus of the scrotum in 

 the male and passing up through the inguinal canal and abdom- 

 inal ring and thence to the cornu or oviduct is functionally of 

 little or no interest. 



The uterus of the mare, with its cornua, constitutes a some- 

 what crucial-shaped organ, the horns leaving the body laterally- 

 at right angles or somewhat recurved. It is located immediately 

 beneath the rectum with its two cornua passing obliquely out- 

 ward and upward on either side. The uterine body is oblong, 

 flattened somewhat from above to below, varying from 5 to 8- 

 inches in length and i J^ to 2)^ inches wide. In the non-gravid 

 organ, the mucous surfaces of its walls are normally in contact 

 with each other. Posteriorly, its cavity is continuous with that 

 of the vagina through the medium of the cervical canal, a con- 

 stricted portion of the genital tube which serves to fix a bound- 

 ary between the two cavities and to, in a measure, close the 

 uterine cavity to the exterior. This canal is a somewhat- 

 elongated and tortuous channel, dependable for its length upon 

 that of the cervix uteri, which it traverses, and for its width upon 

 the development and degree of contraction of the circular muscle 

 fibers of the latter. 



The cervix uteri consists of a constricted area of the uterus in 

 which the circular piuscle fibers are comparatively much more- 

 numerous than in other portions of the organ. Posteriorly the 



