INCISOR TEETH. 291 



the following anatomical parts ; the body, or crown, which is free 

 of the gum, the grinding or cutting surface of which is the table ; 

 ths cervix, or neck, the part invested by the gum ; and the fang, 

 or root, which is inserted into the socket or alveolus. The 

 ulvtoli are more porous, spongy, and vascular than other bone ; 

 they appear and grow with the teeth, and when these decay, 

 become absorbed. They are lined by periosteum, which, 

 reflected from the gum, at the base of the socket, covers the 

 fang, communicating with the pulp cavity, which runs up the 

 fang centre, and contains a highly vascular and nervous organ,- 

 WiQ pulp, whence the dentine of the tooth grows. This pulp is 

 enclosed in a vascular membrane, the dentine tubuli radiating 

 from it. In the aged tooth this membrane becomes ossified, 

 forming the secondary or osteo-dentiyie. The sensory nerve of 

 the pulp comes from the fifth pair; and it is owing to its 

 extreme sensibility that toothache is so severe w^ien the pulp is 

 exposed. 



Teeth are arranged alongside of each other, so as to form the 

 dental arches : these are interrupted at each side, leaving the 

 interdental spaces, or dlcistemce. Teeth are of three kinds ; the; 

 Incisors, or cutting teetb, situated in front of the arches; Canine 

 teeth, or tushes, in the interdental spaces; and Molars, or grinders, 

 behind. The horse, like many other animdls, has two sets ; the 

 temporary or milk teeth, and the permanent or horse tefeth, the 

 former numbering 24, the latter 40. In the mare there are 

 usually. 36 permanent teeth, the tushes being wanting or rudi- 

 mentary. 



INCISOR TEETH. 



The incisor or front teeth in the horse are 12 in number, 6 

 in each jaw ; the upper ones are the longer, their surfaces meet- 

 ing those of the lower ones ; in rare cases the former overlap, 

 constituting a '' parrot mouth." The central pair are the largest, 

 the adjacent ones are called the middle, or lateral, while the 

 outer ones, which are the smallest, are termed the corner incisors. 

 The row of incisors forms a curve, which is part of the so- 

 called dental arch; the younger the tooth the greater the 

 curvature, which gradually decreases with age. The anterior 

 surface of a young incisor tooth presents a triangular shape, with 

 th« base at the table. Viewed laterally it is still triangular, but 



