764 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



the elasticity of the displaced thyroid and arytenoid cartilages corner 

 into play and causes them to assume their original position. The thyro- 

 arytenoid and the lateral crico-arytenoids may likewise serve to produce 

 relaxation of the vocal cords. 



To recapitulate : the tension of the vocal cords is principally due to 

 the crico-thyroid and the posterior crico-arytenoids ; the narrowing of 

 the respiratory part of the glottis is accomplished by the transverse and 

 oblique arytenoids ; and the narrowing of the vocal glottis is accom- 

 plished by the contraction of the thyro-arytenoid and the lateral crico- 

 arytenoids, the former muscle likewise increasing the tension of the 

 vocal cords. 



With the exception of the crico-thyroid all the intrinsic muscles of 

 the larynx are supplied by the inferior laryngeal nerve. The superior 

 laryngeal nerve supplies the crico-thyroid, and is at the same time 

 the sensory nerve of the mucous membrane of the larynx. 



For the mechanism of articulated speech the reader is referred to 

 text-books on human physiology. 



