6 



THE EXTERIOR OF THE HORSE 



The Mouth.^Tlie mouth is an elongated cavity situated between the 

 upjDer and lower jaws. Below it is limited by the lips, laterally by 

 the cheeks, while above it communicates with the cavity of the throat 

 (pharynx). When the mouth is opened the parts exposed are — 1, the 

 teeth; 2, the tongue; 3, the bars; 4, the froenum. 



The Teeth. — The front teeth, of which there are six in each 

 jaw, are distinguished as incisor teeth. Beyond these, in the male 

 animal, are four canine teeth, one on each side above and below. 

 In the mare these are absent. Still farther back will be seen the 



molar or large teeth, or, as they are commoidy 

 termed, grinders, of which there are twenty-four, 

 arranged in rows of six, right and left of each 

 jaw. The eruption of the teeth and the changes 

 which they undergo serve to indicate the age. 

 (See Dentition.) 



The Tongue. — The tongue is the soft Heshy 

 organ hlling up the channel of the mouth. 

 The anterior part is free and capable of being 

 protruded, while the posterior portion is fixed 

 to the lower jaw. Behind, it is connected with 

 a bone (os hyoides) having several joints, so 

 arranged that the organ may be freely extended 

 and retracted. It is acted upon by five pairs of 

 muscles, by which it is capable of being moved 

 in every direction. 



Endowed with a high degree of sensibility 

 and mobility, it plays an important part in 

 the function of mastication and deglutition. 



The Bars. — The bars are represented by 

 that small section of the lower jaw situated 

 in the male between the canine teeth and the 

 grinders. In the mare, where the former are absent, the space is larger, 

 being limited in front by the corner incisors. The bars are covered by a 

 thin, sensitive membrane, on which the bit rests, and are frequently the 

 seat of injury in " pullers", often resulting in death and sloughing of a 

 portion of the jaw-bone. They vary in form in different animals, in some 

 the edge of the bone is sharp and in others rounded. In the former 

 condition the pressure of the bit on the part is more severe in its effects 

 than in the latter, and the difference in the "mouths" of horses is in a large 

 measure due to this cause. As the result of bad breaking and unskilful 

 riding the bars frequently become callous, and the natural sensitiveness 



Fig. 3. — Portion of Lower Jaw, 

 showing Tongue, &c. 



B, Circumvallate Papillae, 

 c. Fungiform Papilla?. 



D, Tongue. 



E, " Bar " or Interdental Space. 



1, Canine Tooth. 3, Lateral Incisor. 



2, Corner Incisor. 4, Central Incisor. 



