28 ANATOMICAL CONSIDERATIONS/ 



and with other structures also lighten that part of the body in which 

 they are situated. 



The passage of the air to the lungs, and the admirable provisions to 

 admit its ingress and its egress, without destroying the mild and charac- 

 teristic aspect of the quadruped, having been described, it now becomes 

 the author's duty to dwell upon the extraordinary conditions which con- 

 serve the passages of the food. Referring again to the diagram here 



A DIAGRAM, EXPLANATORY OF THE SPECIAL PROVISIONS DISCOVERABLE IN THE HEAD OP A HORSE. 



1. The nostril leading direct to — 2. The larynx, situated at the commencement of the windpipe. 3. The 

 tongue. 4. The oesophagus or gullet. 5. The soft palate, which lies upon the tongue and affords a resting- 

 place, whereon reposes the epiglottis, or the guardian cartilage to the entrance of the larynx (2). 6. The 

 guttural pouches, or large membranous and open sacs, containing nothing but atmospheric air. 7. Nasal 

 or frontal sinuses. 



reproduced, we see the mouth, occupied by the tongue, (figure 3,) on the 

 base of which organ reposes a dark body, particularized by the figure 5. 

 This last is the soft palate, which drops pendulous from the osseous roof 

 of the masticatory orifice. Upon the soft palate lies the most forward of 

 the laryngeal cartilages, which is anatomically spoken of as the epiglottis ; 

 while the most backward of the laryngeal cartilages, which are called the 

 aretenoids, repose beneath the roof of the pharynx. This pharynx is the 

 enlarged and muscular commencement of the gullet, the situation and 

 direction of which channel is notified by the number 4. 



We thus perceive in its course the food is apparently thrice forbidden 

 to enter the gullet of the horse. In the first place, there is the soft 

 palate, retained firmly in its position by pressure of the epiglottis. The 

 second obstacle we recognize in the opening of the larynx; the third 

 impediment appears in the aretenoids, that seem to bar all entrance to 

 the tube which leads to the stomach. Moreover, the gullet itself being 

 a muscular organ, in the passive state of semi-contraction is closed ; 

 thus appearing to oppose a further hirjderance to the admission of sus- 



