'%* 



78 



EQUINE ANATOMY. 



two extremities* The superior wall or roof ; the in- 

 ferior or floor with Jacobson's apparatus ; the lateral 

 external with the turbinated bones and meatuses ; the 

 middle meatus having an opening of communication 

 with the sinuses ; the lateral internal is formed by 

 the septum nasi. The anterior extremity forms tlie 

 nostrils ; the posterior looks into the pharynx. Struc- 

 ture : nasal, maxillary, frontal, palate, ethmoid and 

 turbinated bones, middle septum of the nose ; pituit- 

 ary membrane; blood vessels, the ophthalmic and 

 nasal arteries ; nerves, first and fifth pairs of cranial 

 nerves. 



Sinuses. — Five: the frontal, sphenoidal, ethmoidal 

 and two maxillary. All communicate through the 

 middle meatus. The inferior maxillary sinus opens 

 by itself into the nasal fossa. They are all lined by 

 mucous membrane and develop with age. 



Buccal Cavity. — Division : Six regions. 



a. Lips. Superior and inferior, united by com- 

 missures. Two faces; two borders, one adherent 

 and one free. Structure : skin, mucous membrane, 

 muscles, viz: tlie orbicularis, super-maxillo labialis, 

 super-naso labialis, great super-maxillo nasalis, tufts 

 •of the chin and posterior intermediate ; glands, the 

 labial ; blood vessels, the palato-labial and coronary 

 arteries ; nerves, the fifth and seventh cranial pairs. 



