ll-J 



y///: /,/:>///;. i yo/.'V APPARATUS i.\ W.n/.v.i/./.i. 



Ontt-r icidl. This is chiefly constituted hy the tmperinaxillary }nm<; 

 is very rugged, and is divided into three nittu*i>8, or passages, by the 

 turbinatod bones the irregular columns applied against the inner face of the 

 before-mentioned bone. 



The turl>inatcd bones have already been described, and we will only n<>\v 

 refer to the principal features of their organisation. Kaeh is formed of a 

 bony plate rolled upon itself (Fig. 223, 2, 3), and is divided, internally, into 

 two sections, the superior of which forms part of the sinus, and the in- 

 ferior belongs to the nasal fossae ; they are continued, inferiorly, by a tibro- 

 cartilaginous framework, which prolongs their nasal section to the external 

 orifice of the nose. The flexible appendix of the ethmoidal turbinated bone 

 is usually single, sometimes double, and disappears before reaching the alte 

 of the nose. That of the maxillary turbinated bone is always bifurcated, 



Fig. 223. 



TRANSVERSE SECTION OF THE HEAD OF AN OLD HORSE, SHOWING THE ARRANGEMENT 

 OF THE NASAL CAVITIES AND MOUTH. 



1, Nasal fossa; 2, Superior turbiiiated bone; 3, Inferior ditto; 4, Medinn septum of 

 the nose; 5, Central part of the buccal cavity (drawn more spacious tluin it 

 really is when the two jaws are brought together) ; 6, 6, Lateral portions of the 

 same ; 7, Section of the tongue. 



and its antero-superior branch is directly continued by the superior extremity 

 of the internal wing of the nostril. 



The meatuses are distinguished into superior, middle, and inferior, or into 

 anterior, middle, and posterior, as the head is inspected in a vertical or hori- 

 zontal position. The superior passes along the corresponding border of the 

 ethmoidal turbinated bone, and is confounded with the r<x>f of the nasal 

 cavity; it is prolonged, behind, to new the cribriform plate of the ethmoid 



