ANATOMY OF REGIONS. 
197 
ANATOMY OF REGIONS. 
Translated from Pencil and Tons saint's , Precis de Chirurgie V eterinaire ., 
By A. Liautard, M. D. V. S. 
[i Continued from Page 159.] 
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SECTION 3.—REGION OF THE NASAL FOSSAE AND OLFACTORY 
APPARATUS. 
As indicated by its name, the olfactory apparatus serves to the per¬ 
ception of odors; it is besides that the anterior part of the respiratory 
apparatus. In horse, whose velum palate is very long, it constitutes the 
only possible passage for the entrance of air into the lungs. 
The nasal fossae represent two symetrical canals, elongated according 
to the great axis of the head from the nostrils to the pharynx, and sep¬ 
arated by a median bony, cartilaginous septum. Their bony walls are 
formed by the nasal, superior maxillary, ethmoid, turbinated, frontal, 
palate and pterygoid bones. 
Each cavity has the form of an elongated tunnel with an anterior 
and a posterior opening , two lateral walls , a roof or arch , a floor, a pos¬ 
terior chamber , the septum which separates them, the mucous membrane 
which covers all these parts, and at last blood vessels and nerves. 
The anterior opening is flattened sideways ; it has for wall outward¬ 
ly the inferior extremity of the maxillary turbinated bone, divided in 
two branches—the inferior covers the ascending apophysis of the small 
maxillary—the superior has a movable, cartilaginous skeleton, easily felt 
when the finger is introduced in the nostril ; it is covered by the skin, 
and prolonged by a peculiar thick fold which separates it from the false 
nostril, and is continued with the superior extremity of the internal lip 
of the nostril. 
The posterior opening , also called guttural, is about quadrilateral, 
slightly elongated in the direction of the axis of the head, with round angles; 
it is divided in two parts, corresponding to the two nasal fossae, by the 
border of the vomer which supports the median septum. The palate and 
pterygoid bones circumscribe it outwards. Formed by bony walls it is 
not susceptible of expansion. The inflammation or thickening of the 
mucous membrane can alone influence its diameter by narrowing it. 
