1^4 EQUINE ANATOMY. 



Thyroid. 



(Shield-like.) Composed of two portions united in front and 

 above to form its body ; to its superior part the epiglottis is at- 

 tached. The lateral portions have an external surface, covered 

 by muscles ; an internal, covered by mucous membrane ; an an- 

 terior or superior bo7'der, to which the great cornua of the hyoid 

 and the thyro-hyoid membrane is attached ; 2i posterior hox'^^x, 

 showing in front the attachment of the crico-thyroid membrane, 

 and behind an articulating facet with the cricoid. 



Cricoid. 



(Like a ring.) Shaped like a seal ring with the seal upward, 

 and shows an external face, smooth, and on its flattened portion 

 spaces for the origin of the posterior crico-aiytenoids, outside 

 these the articular facets for the thyroid ; an internal face, cov- 

 ered by mucous membrane ; a superior boi-der, with facets for the 

 arytenoids and attachment of crico-thyroid membrane ; an infer- 

 ior border, responding to the trachea. 



Epiglottis. 



A soft, flexible lid that covers the entrance to the larynx. It 

 has an anterior face, which gives attachment to the hyo-epiglot- 

 tideus ; 2i posterior, covered by mucous membrane; a circumfer- 

 ence and base attached to the thyroid. 



Arytenoids (two). 



(Like a pitcher.) Are situated above the cricoid and near the 

 top of the larynx. They are irregularly quadrilateral and show 

 an internal face lined with mucous membrane ; an external, giv- 

 ing attachment to arytenoid, thyro arytenoid and lateral crico- 

 afytenoid muscles ; a superior border, united with the opposite ; 

 an inferior, giving attachment to the vocal cord ; an anterior, 

 joining with its fellow and giving the pitcher appearance ; 2. post- 

 erior, which articulates with cricoid. 



Articulations of Cartilages. 



Thyroid, with co7'nua of hyoid, by thyro-hyoid ligament and 

 thyro-hyoid membrane. 

 Thyroid with c?'icoid. 



Capsular ligaments for facets and crico-thyroid membrane. 

 Arytenoids with cricoid. 

 By capsular ligaments for facets. 

 Arytenoids with thyroid. 

 By vocal cords, a pair of fibrous bands which enclose a triangu- 



