58 BOVINE OBSTETRICS 



which might be looked upon as the deep perineal fascia, viz.: 

 the perineal muscles, the sphincter of the anus, the depres- 

 sor of the tail, the retractor of the vagina, and some muscular 

 fasciculi extending between the broad ligaments and vulva. 



As a consequence of these anatomical conditions, the 

 expulsion of the calf experiences some obstacle at this spot; 

 the dilatation of the vaginal walls is painful, on account of the 

 numerous sensory nerves. 



The vaginal wall further consists of a muscularis and 

 mucosa. The muscularis shows externally longitudinal, in- 

 ternally circular fibres, increasing in number at the vestibule, 

 which represents the thickest portion of the muscular layer. 

 Between both layers are numerous elastic and fibrous fasciculi. 

 The internal surface of the genital passage is a mucosa. 

 Beginning at the spot where the foetus develops, and up to the 

 vulva, viz., the whole tract through which the calf passes, we 

 find a dilatable wall, the inner surface of which is lined with a 

 mucous layer. In the unimpregnated state, the cervix uteri 

 lies in the pelvic cavity or upon the anterior pubic border, but 

 during advanced pregnancy in the abdominal cavity. That 

 part of the cervix uteri extending into the vagina, known as 

 the vaginal portion of the uterus, remains firmly closed during 

 pregnancy. The anatomical arrangement of the cervix uteri 

 permits it to be opened to such an extent that the body of the 

 uterus and vagina form a common canal. As a consequence 

 of the elasticity of the walls, it is possible to obtain au 

 amount of dilatation only limited by the bony canal. 



II. 



CAUSES, COURSE AND TREATMENT OF NORMAL 

 BIRTH. 



Whenever the foetus has reached full maturity, it is ex- 

 pelled. This ends intra-uterine life, and extra-uterine life 

 begins. This course, subject to many deviations, including 

 mother and foetus, is termed birth or partus, the act itself 



