INCISIONS. 131 



ment, to avoid the possibility of extending the incision beyond the 

 necessary limits. 



The direction and size of incisions require careful consider- 

 ation. They must run as nearly parallel with the direction of the 

 muscular fibres and the large blood vessels and nerves of the 

 region as the condition of the part will permit. 



Their direction should also correspond to that of the long 

 axis of the part or tumor undergoing operation, and in such a 

 manner that the retraction of the sMn wiU not tend to separate 

 the borders of the wound. Sometimes, according to the unavoid- 

 able natural motions occurring in a region, the normal folds of 

 the skin should be considered. A vertical incision is always pre- 

 ferable, as more readily allowing the escape of liquids, pus or 

 otherwise, which may have accumulated. 



As much as possible, and generally, incisions should be made 

 with a single stroke, and of the full length and depth required by 

 the further steps of the operation. Besides diminishing the suf- 

 fering of the animal, such an incision will greatly facilitate all 

 the subsequent manipulations of the operator. 



Incisions are made by four principal methods : first from 

 without inwards; second, from within outwards; third by sub- 

 cutaneous division; and fourth by the slicing, scraping or shaving 

 method. In the first two modes the instrument may be turned 

 in five directions. 



(a) Towards the operator, by beginning at the farthest point 

 aud moving the instrument in the direction of his own person. 



{b) From the operator, by reversing the former movement. 



(c) From left to right and transversely, the instrument being 

 held with the right hand. 



(c?) From right to left, or in the opposite direction, with the 

 instrument in the left hand. 



(e) From above downwards, in a vertical or slightly oblique 

 direction. 



Incisions from left to right and from above downwards are the 

 most convenient, and for this reason the surgeon practices them 

 as much as possible. 



1st. Incisions from without inwards. — These incisions are 

 carried from the surface of the skin towards the deep structures 

 underneath. They may be made with any kind of bistoury, but 

 the convex is to be preferred. 



