444 



FCE TA L D YS TOKIA . 



and are of the nature of deformity of the neck or head, or both ; we 

 have alluded to them when treating of " Contractions," at p. 392. 



It will readily be understood why misdirection of the head should 

 prove a serious obstacle to delivery, when we remember the part the 

 nose and cranium play in dilating the os and genital canal, and how 

 largely this voluminous region must add to the bulk of the neck, and 

 render expulsion impossible. 



Deviations of the head may be met with in the four principal positions 

 of the anterior presentation ; and they may occur alone, or be com- 

 plicated with misdirection of the fore-limbs. These will not again be 

 referred to, but the head will be studied in three different deviations 

 from the normal direction : 1. Doivmvard deviation, the nose being 



■^-#^ 



Fi?. 132. 



Anterior Presextation, Dorso-S.vcral Position : Downward Deviation of the 



Head. 



towards the trachea, and the " poll " or upper ridge of the neck present- 

 ing ; 2. Bent under the body, the neck being flexed ; 3. Lateral devia- 

 tion to the right or left side, the head being carried towards the shoulder 

 or flank of that side, the side of the neck presenting ; 4. Upicard devia- 

 tion, the head being bent upwards and backwards in the direction of 

 the withers, or twisted to the right or left side of the chest, with the 

 throat — either straight or twisted — presenting. 



Doivmvard Deviation. 



This is usually the deviation of the head met with in hydrocephalus, 

 though it is not very uncommon when the cranium is normal and the 

 foetus well formed. It is usually met with in the dorso-sacral position, 

 though it is not infrequent in the dorso-pubic ; it perhaps occurs oftenest 

 in the Cow, 



The cause is usually ascribed to premature rupture of the foetal 

 membranes, the deviation occurring when the foetus is entering the 

 pelvis. If the head is not exactly in the axis of the inlet, but inclines 

 a little downwards and is at the same slightly flexed, the nose comes 

 in contact with the brim of the pubis, and is retained there ; while the 



