The Neck. 485 



hyoid and sterno-thyroid muscles are identified. Sep- 

 arating these muscles with the handle of the scalpel and 

 avoiding any veins that may appear, the trahcea, covered 

 with fascia, is reached, the isthmus of the thyroid is dis- 

 placed downwards, and the trachea, having been steadied 

 by a hook introduced into the cricoid cartilage, is incised 

 with a knife, held with the cutting part towards the 

 patient's chin, and inserted about three rings below the 

 cricoid cartilage so as to cut upwards. The margin of the 

 wound in the trachea is held open with a pair of forceps 

 and the tracheotomy tube introduced. Should the isth- 

 mus be in the way, while operating on children, it may be 

 safely divided, as it is very small in these patients. 



Laryngotomy may occasionally be performed as a 

 substitute for tracheotomy, but should not be undertaken 

 in children under thirteen, as, in them, the crico-thyroid 

 space, through which the incision is made, is very narrow, 

 since, even in the adult, the height of the space is only 

 about half an inch. An incision is made in the median 

 line over the lower part of the thyroid cartilage, over the 

 crico-thyroid space and the cricoid cartilage ; the interval 

 between the muscles is identified and these structures 

 separated, the crico-thyroid space exposed and the mem- 

 brane divided just above the cricoid cartilage, so as to 

 avoid the crico-thyroid artery that runs across, immediate- 

 ly below the thyroid cartilage. 



Diseases of the region of the Neck. Burns. When 

 a burn is deep enough to affect the platysma, considerable 

 deformity, as a rule, results from its subsequent contrac- 

 tion, because of the extensive surface presented by this 

 muscle and its connection with the muscles of the lower 

 part of the face. Abscess. An abscess, situated outside 

 of the deep fascia, may spread externally, without any 

 special direction being imparted to it, by any arrangement 



