156 EQUINE ANATOMY. 



Roof. 



Nasal, frontal, ethmoid and sphenoid. 



Sides. . 



Nasal, inter-maxillary, superior maxillary, palate and turbi- 

 nated. 



Median Septum. 



Perpendicular plate of ethmoid, vomer and mesial cartilage. 

 Openings of Communication. 



Anteriorly, two nostrils. 



Posteriorly, two posterior nares, with pharynx. 



Laterally, by a common opening into the middle meatus, the 

 superior maxillary, sphenoidal, ethmoidal and frontal sinuses. 

 The inferior maxillary opens alone. 



Above, the openings of the cribriform plate transmitting the 

 olfactory nerves. 



Below, the incisive canal, leading to the mouth. 



THE NOSTRILS, 



Are the two oblong openings in the anterior and inferior portion 

 of the nose. 



Structure. 



Of three cartilages, the first one prolonged from the tip of the 

 nasal bones, two lateral cartilages meeting in the median line in 

 an x shape and attached at the side to the inter-maxillary bones 

 by a broad expanded portion; the lower extremity forms the 

 curve of the nostril. 



Muscles. 



Already described. 



Skin. 



Thin and sensitive. 

 Mucous Membrane.- 



Covers the whole surface of the nasal cavities and continued 

 into the sinuses. 



Divided into two portions. The olfactory in the upper one- 

 third, which is thin, with columnar and stratified epithelium, and 

 the cells of Schultze. These are fusiform in shape, with a deep 

 prolongation, continuous with the olfactory nerve, and a super- 

 ficial near the free surface of the membrane. It is supplied by 

 the first nerve. 



The Schneiderian is thick, soft and spongy, with numerous 



