MECHANISM AND CHEMISTRY OF RESPIRATION 211 



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lake the framework of the organ of voice. Their arrange- 



jnt there is as follows: 



The uppermost cartilage, the thyroid, a broad U-shaped 



irtilage, lies horizontally with the opening at the back; its 



>nt curve protrudes and is 



It through the skin as 

 'Adam's apple"; Fig. 105. 

 The tips of the sides of the 

 U at the back have short 

 vertical growths on them, 

 one extending upward and 

 one downward on each arm 

 of the U. 



Below the thyroid is the 

 cricoid cartilage. This is a 

 complete ring, narrow in 

 front and broad behind. 

 Its lower hind border is 

 hinged on each side to the 

 lower prongs on the thyroid; 

 Fig. 105. On the upper edge 

 of the hind border of the 

 cricoid are located the two 

 small, triangular arytenoid 

 cartilages shown in Figure 

 106, which represents a view 

 looking into the larynx from 

 above. These four cartilages together with tendons, muscles 

 and connective tissue make up the voice box. 



The passage through this structure will be seen in Figures 

 106 and 107, to be nearly closed by two transverse, curtain- 

 like membranes attached at the back (one to each arytenoid 

 cartilage) , along the sides, and at the front (to the thyroid) . 

 In front these two membranes come nearly together, while 

 they are separated at the back, thus leaving an approximately 



FIG. 105. THE LARYNX AS VIEWED 

 FROM THE LEFT SIDE 



Slightly enlarged. 



