LABYNGOTOMY AEYTENECTOMY. 465 



animal is cast, and he is tlirown in. the usual maimer, on a good 

 bed of straw or moss or litter. The chloroform bag is put on, and 

 when the required state of narcosis is induced, the animal is placed 

 on his back, and maintained there by sacks fiUed with straw, placed 

 close under each side of the body. The neck and head are ex 

 tended in a hne with the body, the head placed on the vertex and 

 kept steady by an assistant. The operator places himself in a 

 kneeling position, on the off, or right side of the body, if right 

 handed, beside the neck, with his back to the shoulder and face 

 toward the head." 



The operation is divided into three stages : 



First Stage. — " With a scalpel, an incision of from four to six 

 inches in length is made through the skin, the middle line of the 

 laxynx and trachea, opposite the posterior border of the lower jaw, 

 extending from the body of the thyroid cartUage to the second or 

 third tracheal ring. This exposes the subscapulo-hyoid, sterno- 

 hyoid and sterno-thyroid muscles, which are incised to the same 

 extent, and as close as possible to their line of junction {raphe) 

 in the middle, the section being then carried through to the larynx 

 and trachea. There is a variable amount of hemorrhage now to 

 contend with, which, if only oozing, may be checked by sponging 

 it dry until the blood has ceased to flow ; and if it comes from 

 twigs of arteries or veins, they may be seized, and twisted, or 

 ligated." 



Second Stage. — "The middle crico-thyroid ligament, cricoid car- 

 tilage, and one, two or three tracheal rings are cut through, in a 

 straight line, exposing the interior of the larynx and trachea. If 

 blood vessels are cut, they should be taken up. A retractor is 

 applied to the sides, and these being pulled gently apart by an 

 assistant, there is ample space in which to manipulate. The con- 

 vex lower border of the arytenoid on each side can now be seen, 

 and if the respiration is deep, that which is next the operator (the 

 right), wiU be observed to move actively from the side toward the 

 middle ; while if the roaring is due to paralysis of the left dilator 

 muscle, there is no movement in the opposite cartilage. "When the 

 breathing is very tranquU, which is often the case, the right carti- 

 lage moves almost imperceptibly, and it becomes necessary to as- 

 certain whether the left one is really immovable. This can be 

 done by passing the finger, or a long probe, up toward the epi- 

 glottis, when the act of swallowing will be excited, during which 



