58 THE ROARING OPERATION 



veals the triangular crico- thyroid ean ligament with it? 

 rounded apex directed forward and its lateral borders 

 sharply defined by the hard borders of thealse of the thyroid 

 cartilage, while the base of the triangle rests upon the 

 more elastic anterior border of the cricoid cartilage. 



Having carefully identified the crico-thyroidean ligament, 

 place the back of the scalpel against the anterior border of 

 the cricoid cartilage, accurately upon the median line, the 

 point directed obliquely backwards toward the cavity of the 

 trachea. Push the scalpel through the ligament into the 

 laryngeal cavity, and carry the incision forward on the 

 median line to the body of the thyroid cartilage. 



Detach the slotted piece from the laryngeal retractor (Fig. 

 i8) and insert the closed retractor into the incision through 

 the ligament, the rachet end of the speculum being directed 

 toward the trachea, the curved spurs on the jaws of the 

 retractor resting within the cricoid ring. Open the dilator 

 to the full extent of the crico-thyroidean space. Insert the 

 hook of the slotted piece into the cavity of the thyroid 

 cartilage and secure in position by means of the thumb screw 

 as shown in Fig. 20. 



Illuminate the cavity of the larynx. In the standing 

 animal, when facing good light, the natural illumination 

 suffices. The illumination may be improved with the aid 

 of a hand mirror. 



Excellent illumination is always available by means of a 

 reflecting electric lamp. With a good lamp the illumination 

 may be perfectly controlled in a dark room or in the dark- 

 ness of night. When the animal is cast and turned upon 

 his back, the light rays should enter the larynx from above 

 obliquely downward and forward. If the operation is being 

 done in the open field by sunlight, the patient's head should 

 be directed away from the sun, or good illumination fails. 

 Observe the motion of the arytenoid cartilages, and de- 

 termine, if not previously done, whether the paralysis is 



