THE LARYNX 7, 



area should undergo careful preparatory treatment in the way of shaving 

 and cleansing. 



A cutaneous incision is made in the median line, and should 

 extend from the body of the thyroid to the second tracheal ring. 



The incision should next be carried through the thin layer of 

 panniculus, and subsequently, if sufficient care be taken to strike the 

 median line, when the lips of the wound are separated, the delicate 

 septum between the two inner divisions of the sterno-thyro-hyoideii 

 muscles may be seen. These muscles are made very tense owing to the 

 manner in which the head has been disposed. 



The part should now be carefully sponged and the operation 

 continued by making an incision along the septum referred to. Little, 

 if any, haemorrhage arises from the last-named step. 



The scalpel should next be held with but a short portion {e.g., 

 half an inch) of the blade exposed, and plunged into the crico- 

 thyroid membrane ; and having done this, the membrane should be 

 slit from the thyroid to the cricoid cartilages. 



All that now remains is to turn the cutting edge of the knife 

 towards the cricoid cartilage, and cut through the latter by applying 

 steady pressure. By separating the edges of the wound thus made a 

 good view of the interior of the larynx is obtained. 



Care must be taken not to injure the thyro-laryngeal branch of 

 the carotid artery. The laryngeal division of this vessel runs upwards 

 to the larynx a short distance to the outer side of ihe seat of operation, 

 whilst its thyroid branch takes a retrograde direction to enter the 

 upper or anterior face of the gland. 



The posterior extremity of the submaxillary gland lies to the outer 

 side of the anterior extremity of the incision, and to the outer side of this 

 again lie the excretory duct of the parotid, namely, the Duct of Stenson, 

 and the submaxillary artery with its accompanying vein. 



The edges of the wound should be hooked back and fixed whilst 

 the examination of the interior of the larynx is being carried out. 



