226 THE ANATOMY OF THE HORSE. 



by laryngeal mucous membrane ; the outer surface 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 post^ro-external angle, which is thick and rounded, 

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

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

 cartilage representing the cornicida laryngis of man. This curves back- 

 wards and inwards ; and with the corresponding 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 fibro-cartilage, the texture of the arytenoid is hyaline 

 cartilage. 



The Epiglottis 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 cartilage 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 upright 

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

 rests on the body of the thyroid. From each side of it an irregular bar 

 of cartilage projects horizontally backwards. The epiglottis is composed 

 of yellow fibro-cartilage. 



ARTICULATIONS, LIGAMENTS, AND MEMBRANES OP 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 thyroid cornu (heel process) of that bone being connected by liga- 

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

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

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

 ihyro-hyoid memh-ane, 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-elastio 

 membrane — the crico-tracheal ligament. 



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 of the cricoid in a diarthrodial joint, provided with a 



