332 



ELEMENTARY PHYSIOLOGY 



LESS. 



gether, in the re-entering angle of the thyroid cartilage 

 rather lower than half-way between its top and bottom. 



Now when the arytenoid cartilages diverge, as they do 

 when the larynx is in a state of rest, it is evident that the 

 aperture of the glottis will be V-shaped, the point of the 

 V being forwards, and the base behind. 



For, in front, or in the angle of the thyroid, the two 



^r-./i. 



Fio. 105. — The parts si'RROUNmNo the Glottis partially dissected 



AND VIEWED FROM ABOVE. 



Th. the thyroid cartilage ; Cr. the cricoid cartilage ; F, the edges of the 

 vocal ligaments bounding the glottis; Ary, the arytenoid cartilages; 

 Th.A, thyro-arytcnoid ; C.aA. lateral criro-arytenoid ; C.a.-p, posterior 

 crico-arytenoid ; Ar.ip, posterior arytenoid muscles. 



vocal ligaments are fastened permanently close together, 

 whereas, behind, their extremities will be separated as far 

 as the arytenoids, to which they are attached, are separated 

 from each other. Under these circumstances a current 

 of air passing through the glottis produces no sound, the 

 parallelism of the vocal cords being wanting ; whence it 

 is that, ordinarily, expiration and inspiration take place 

 quietly. Passing from one arytenoid cartilage to the 



