268 



ANIMAL PHYSIOLOGY. 



rotation, and the superior being united by ligaments of some 

 length to the hyoid bone. 



Surmounting the back part of the cricoid are the arytenoid 

 cartilages, two bodies shaped like three-sided pyramids, 

 articulated at their bases to the cricoid cartilage, and curved 

 backwards at their apices, so as to give the mucous mem- 

 brane which covers them an appearance in the middle line 

 like the spoilt of a water-jug, from which they get their 

 name. At the anterior angle of the 

 base, they are prominent, and give 

 attachment to elastic* fibres which 

 pass directly forwards to be attached 

 to the thyroid cartilage close to the 

 middle line. These are what in 

 1 strict anatomical language are known 

 as the vocal cords. 



But by the term vocal cords are 

 most frequently understood, not 

 merely the few fibres mentioned, 

 but likewise the folds of mucous 

 membrane in which they lie. The 

 mucous membrane, disposed cylin- 

 drically in the interior of the cricoid 

 cartilage, approaches the middle line 

 from each side to cover the elastic 

 fibres described; and is then ab- 

 ruptly reflected outwards, forming 

 on each side a hollow called the 

 ventricle, prolonged into a little sac- 

 Fig. 131 -MESIAL SEC- d i n front, and limited above by 

 TION OF LARYNX, , ., J ! , .. ,, 1 ,, - 7 '. 



Hyoid bone ; b c d, a semmmar fold called the jalse vocal 

 thyroid, cricoid, and cord. The first-mentioned folds, or 

 arytenoid cartilages ; e, true vocal cords, are those by whose 

 true vocal cord;/, false ^ration the voice is 'produced; in 

 vocal cord, and beneath T , , i 



it the ventricle of the vocalization they are approximated 

 larynx; g, epiglottis; A, to the middle line; they are pro- 

 tongue, tected with squamous epithelium 

 from the force of the air which whistles past them, and have 

 their position and tension regulated by muscles. The space 

 between them is termed the glottis or rima glottidis. 



