THE LARYNX 



:m 



this membrane ; or, if the thyroid cartilage is fixed, the 

 cricoid cartilage moves in the same way upon its articula- 

 tions with the thyroid. When the thyroid moves down- 

 wards or the cricoid upwards, 

 the distance between the front 

 part of the thyroid cartilage 

 and the back of the cricoid is 

 necessarily increased ; and when 

 the reverse movement takes 

 place the distance is diminished. 

 There is, on each side, a large 

 muscle, the crico-thyroid, 

 which passes from the outer 

 side of the cricoid cartilage 

 obliquely upwards and back 

 wai-ds to the thyroid, and pulls 

 the latter down ; or, if the 

 thyroid is fixed, pulls the cricoid 

 up (Fig. 103, G.th). 



Perched side by side upon 

 the upper edge of the back part 

 of the cricoid cartilage are two 

 small irregularly-shaped but, 

 roughly speaking, pyramidal 

 cartilages, the arytenoid car- 

 tilages (Fig. 105, Ary). Each 

 of these is articulated by its 

 base with the cricoid cartilage 

 by means of a shallow joint 

 which permits of very varied 

 movements, and especially al- 

 lows the front portions of the two arytenoid cartilages to 

 approach, or to recede from, each other. 



It is to the forepart of one of these arytenoid cartilages 

 that the hinder end of each of the two vocal ligaments is 

 fastened ; and they stretch from these points horizontally 

 across the cavity of the larynx, to be attached, close to- 



FiG. 104. — Vertical and 

 Transverse Section 



THROUGH THE LaRYNX, 

 THE HINDER HALF OF 

 WHICH IS REMOVED. 



Ep. Epiglottis ; Th. thy- 

 roid cartilage ; a, cavities 

 called the ventricles o_f 

 larynx above the vocal liga- 

 ments (F); X the right 

 thyro-arytenoid muscle cut 

 across ; Cr. the cricoid car- 

 tilage. 



