458 OPERATIONS ON THE RESPIRATORY APPARATUS. 



but our experience has taught us that the recumbent position is 

 the safest, especially if there are plenty of assistants at hand, with 

 instructions to keep the head of the animal steady, and in a mode- 

 rate state of extension on the neck. 



The operation is divided into three steps ; 1st, The incision of 

 the skin and dissection of the parotid ; 2d, The jyuncture of the 

 pouch through the occipito-hyoideus muscle ; and 3d, The estab- 

 lishment of the counter-opening. 



Before considering these three steps, it will be well to answer 

 sundry important questions put by Lecoq in the first good de- 

 scription of the operation, made in 1841. 



'Where shall the puncttire he made ? 



The anatomical disposition, which we have already examined, 

 suggests as an answer to this query, that the occipito-hyoideus 

 inuscle is the proper place for the puncture. Its inner side is 

 lined with the mucous membrane of the pouches, and as has al- 

 ready been remarked, when this is distended by fluid and becomes 

 tense and resisting, it is in a much better condition for the pass- 

 age of the knife through its thickness than when flabby and soft, 

 and therefore movable and shifting, as if endeavoring to evade the 

 knife. At any other point the pouches are so surrounded by im- 

 portant blood vessels and nerves that the operation is precluded 

 by the ganger which would be incurred by attempting it. 



Where must the first incision he made to reach the occipito- 

 hyoideus muscle? 



It would be easy to reach the muscle by a division of the paro- 

 tid gland, bvit this would involve the formation of a fistula, and a 

 wound difiicult to heal, to avoid which the gland must be raised 

 out of the way. This should be done by raising the posterior bor- 

 der, where it is loose and free from blood vessels or nerves of 

 importance, in j)reference to doing so by disturbing the anterior 

 border or superior extremity, where the posterior auricular artery, 

 the facial nerve and the sub-zygomatic artery are situated. The 

 superior extremity of the incision must begin near the inferior 

 border of the tendon common to the splenius and small com- 

 plexus muscles, a little in front of the transverse border of the 

 atlas, and extend downward for a space of two or three inches. 

 Upon v}hat point of the muscle must the puncture he made? 



The answer to this is — upon the central portion of the muscle. 

 The introduction of the bistouiy into the superior part of the 



