74 Roaring in Horses. 



the " pharynx," and its lower opening is continuous with 

 that of the windpipe, or trachea. It is placed in the same 

 direction as the latter, which, again, has the same direction 

 as the neck. Usually it is at an angle when the neck is more 

 or less horizontal, its long axis being obliquely directed for- 

 wards and upwards ; but it becomes vertical as the head 

 and neck are raised or extended. It will be considered as 

 vertically placed, in order to facilitate description. 



It is, fundamentally, a dense cartilaginous box, made up 

 of several pieces which can move on each other ; and it is 

 composed, intrinsically, of cartilages, muscles, ligaments, 

 mucous membrane, nerves, and bloodvessels. The latter ■ 

 need not be alluded to here. 



CARTILAGES. 



The cartilages which constitute the framework of the 

 larynx are five in number — the Thyroid, Cricoid, two 

 ArytcBnoid, and the Epiglottis. 



There are also two pairs of rudimentary cartilages, only 

 one pair of which — the cartilages of Santorini — may be 

 noticed in this place. 



1. Thyroid Cartilage {Cartilago thyroidea). Figs. 1, e ; 

 2,dd; 3, d e. — This is the largest piece in the larynx, form- 

 ing, as it does, the two sides and a portion of the front of 

 the box. Its middle part, the body (Fig. 3, e), is situated 

 in front, and is a short, narrow, protuberant mass, known in 

 human anatomy as Adam's apple {pomum Ad'ami) ; it is 

 usually bony in old horses. It suddenly expands in bend- 

 ing round, to form the sides or wings (alee) of the larynx, 

 each of which is a wide, somewhat quadrangular plate, 

 slightly convex externalljr, concave internally, extending 

 the whole length, from before to behind, of the organ. 

 Owing to its shape, a somewhat large triangular space is 

 left between the wings in front, which is filled in by an 

 elastic membrane or ligament, the middle crico-thyroid 

 (ligamentuni crico-thyroideum medium). 



