218 



STRUCTURE OF THE VERTEBRATES 



Vocal cords are found first in the anuran amphibia. These are 

 membranous bands of tissue attached to the arytenoid car- 

 tilages, and partially closing the glottis on either side. The con- 

 traction or relaxation of these membranes by movements of the 

 larynx give a limited change in pitch to the voice. This primitive 



Glottis 



Vocal- 

 cords 



C. Glottis 



B. Dorsal View 



Fig. 128. Structure of the Human Larynx. (A) Shows the thjToid car- 

 tilage attached to the hyoid; (B) is a dorsal view with the esophagus 

 removed; and (C) shows the appearance of the glottis as seen through 



the mouth. 



