SENSE ORGANS. 20Q 



the chest as a fulcrum for the action of the great 

 muscles of the trunk and limbs. 



MUSCLES OF THE LARYNX. 



The muscles by which these changes are accom- 

 plished are numerous, some tightening, some loosening 

 the cords, some closing the chink. The following are 

 the main ones : 



Crico-thyroids ) ^ 



_ . ' . \ Tensors. 



Crico-arytenoids, posterior ) 



Thyro-arytenoids \ Relaxers. 



Inter-arytenoids ) .-,, 



r (closers. 

 Crico-arytenoids, lateral ) 



Of the tensors, the crico-thyroid, as seen in Fig. 130 

 arising from the cricoid, takes hold of the thyroid and 

 pulls it downward, and its upper part forward. The 

 crico-arytenoids, arising from the cricoid behind, take 

 hold of the arytenoids and pull them backward. These 

 may be seen in Fig. 134, being indicated by the dotted 

 spaces. These two, the one pulling the angle of the 

 thyroid forward and the other pulling the arytenoids 

 backward, stretch the vocal cords. These, therefore, 

 are the stretchers or tensors of the cords. 



The relaxers must pull the thyroid and the arytenoids 

 toward one another. This is done by the thyro-aryte- 

 noids, which run fore and aft within the larynx from 

 the thyroid to the arytenoids just outside of the vocal 

 cords. They are seen in Fig. 133. 



The closers are of two kinds — one, the inter-arytenoid, 

 runs from arytenoid to arytenoid and brings these to- 

 gether ; the other, the lateral crico-arytenoids, rotate 

 the arytenoids in such wise as to bring together the for- 

 ward projecting points to which the cords are attached. 

 These can not be well shown except on a model. 



