LATERAL FACES OF THE HEAD. 59 



lated, produced by the bulging of the cheek in consequence of the 

 accumulation of aliment between the latter and the molar arcades. It 

 is observed principally in old horses. Horse-merchants always take 

 the precaution to cleanse the mouth of such horses with vinegar and 

 water before they are presented for sale, in order to mask the fetid 

 odor which it exhales. The employment of these manoeuvres, how- 

 ever, is insufficient for those who examine carefully the condition of 

 the teeth, on the one part, and pouch in the cheek on the external sur- 

 face, on the other. The latter, on account of its continual distention, 

 is not closely applied upon the molars, but remains flabby, pendulous, 

 and presents longitudinal ridges. We can understand that this defect 

 of itself does not depreciate much the value of the horse, but that its 

 gravity depends upon the cause which produces it and the means which 

 remedy it. 



Blemishes. The blemishes of the cheek are traces of setons, indicating 

 that the animal has been treated for an affection of the eyes or of the nasal cavi- 

 ties. A seton improperly applied to this region may produce paralysis of the cor- 

 responding lips by injuring the branches of the sub-zygomatic plexus of nerves ; 

 the former is then drawn to the side opposite to that of the paralysis. 



A salivary fistula, following an accidental opening of the duct of Stenon, may 

 be found on the maxillary fissure or the side of the face. A transparent, limpid 

 liquid escapes from the opening, perhaps in jets, when the food is masticated on 

 that side. It is a serious accident, on account of its long continuation, the ineffi- 

 ciency of its treatment, and the malnutrition which results from the loss of the 

 saliva. 



F. The Nostrils (Fig. 19). 



Situation ; Limits ; Form ; Divisions. The nostrils are 

 the external orifices of the nasal fossa?, and the only passage through 

 which the air can enter the lungs in solipeds, which respire only 

 through the mouth in ordinary conditions. Designated as right and 

 left, and situated at the inferior extremity of the head on each side of 

 the median line, they are limited, internally, by the " tip" of the nose ; 

 below, by the superior lip ; and, externally, by the cheek and the face. 

 The form of the orifice is auricular or crescent-shaped, extending 

 from above to below, and slightly from without to within. They 

 present two lips, wings, or alee, and two commissures. 



Anatomical Base. a. The internal ala or lip, flattened and thin at its 

 free border, which is convex, is turned downward and outward, and is constituted 

 centrally by the nasal cartilage, whose flat portion, with the one on the opposite 

 side, forms the cartilaginous plate of the extremity of the nose. The latter, covered 

 externally by the transversalis nasi muscle and the skin, and internally by soft 

 skin and mucous membrane, is prolonged downward and outward through the 

 inferior commissure, to terminate in the external ala. 



