226 THE ANATOMY OF THE HORSE. 



by laryngeal mucous membrane ; the outer surfiice receives the insertion 

 of the thyro-arytenoid muscle ; the posterior surface is covered by the 

 arytenoid muscle. The base of the cartilage possesses within its area a 

 smooth, depressed facet for articulation with the cricoid. Two of the angles 

 of the base require particular notice, viz., the anterior angle, which is 

 pointed, and projects horizontally forwards to receive the insertion of the 

 vocal cord ; and the postero-extemal angle, which is thick and rounded, 

 and receives the insertion of the crico-arytenoid muscles. The apex is 

 directed upwards, and is prolonged by a slender piece of yellow fibro- 

 cartilage representing the cornicula laryngis of man. Tliis curves back- 

 wards and inwards ; and with the cori'esponding process of the opposite 

 side forms, behind the upper aperture of the larynx, the pitcher- 

 like lip. Except in the apical prolongation, which is composed of 

 yellow or elastic fibi'o-cartilage, the texture of the arytenoid is hyaline 

 cartilage. 



The Epiglottls is shaped like an ovate, pointed leaf. Its anterior 

 surface is concave in the vertical direction, and convex from side to side. 

 Near the base it receives on the middle line the insertion of the hyo- 

 epiglottideus muscle. The posterior surface has the converse configura- 

 tion, and presents numerous pits in which are lodged mucous glands. 

 The borders of the cai-tilage are convex, and they are free above, but 

 below they are enveloped by the aryteno-epiglottic folds of mucous mem- 

 brane. The apex is pointed, and curved forwards in the iipright 

 position of the cartilage. The base of the cartilage is expanded, and 

 rests on the body of the thyroid. Fi-om each side of it an irregular bar 

 of caililage projects horizontally backwards. The epiglottis is composed 

 of yellow fibro-cartilage. 



ARTICULATIONS, LIGAMENTS, AND MEMBRANES OF THE LARYNX. 



Mode of Union with the Hyoid Bone. The larynx is suspended to the 

 base of the skull through the intervention of the hyoid bone, the tip of 

 the thjToid comu (heel process) of that bone being connected by liga- 

 mentous fibres (without a synovial membrane) to the so-called siqyeHor 

 comu at the supero-posterior angle of the thyroid ala. The connection 

 between the hyoid bone and the larynx is furtlier maintained by the 

 thyro-hyoid membrane, which is attached, on the one hand, to the body and 

 thyroid cornua of the hyoid, and, on the other, to the body and upper 

 edge of each wing of the thyroid cartilage. 



Mode of Union with the Trachea. The lower edge of the cricoid 

 cartilage is connected to the first ring of the trachea by a fibro-elastic 

 membrane — the aico-tracheal lu/ament. 



Union of the Cricoid and Thyroid Cartilages. The postero-inferior 

 angle, or inferior cornu, of each thyroid ala is articulated to the concave 

 facet on the bezel jof the cricoid in a diarthrodial joint, provided with a 



