BOXES OF THE SPINE, OR A^ERTEBR.E. 349 



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the cavity of the mouth. They unite with each other at the 

 middle of the upper lip, and with the superior maxillary bones 

 where the tushes rise. They hold the six upper incisors, or 

 cutting teeth. 



The lower javj, or inferior maxillary, bone constitutes the walls 

 of the lower part of the cavity of the mouth. It is a very 

 large bone, having two sides exactly alike, and which, at an 

 early period, are not solid at the point of the chin. It articu- 

 lates, or joins, to the bones of the skull by a movable hinge- 

 joint. It receives the six lower grinders on each side, the two 

 tushes, and the six lower incisors. T^o bone in the skeleton 

 has so much to do with the beauty of the animal as this. If 

 the lower jaw is not perfect, but large and clumsy, we at once 

 infer coarse stock in the horse. 



BONES OF THE SPINE, OR VERTEBRAE. 



The spine, or back-bone, is composed of thirty-one pieces or 

 distinct bones, united together by tough, elastic cartilage, situ- 

 ated between the different pieces, which are still more firmly 

 bound together by many straps of ligament. These bones are 

 called vertebrae. There are seven of the neck, called cervical 

 vertebrae; eighteen of the back, called dorsal vertebrae; six of 

 the loins, called lumbar vertebrae. A large canal or hole 

 passes through all the vertebrae, and terminates in the sacrum, 

 or rump-bone. It is filled by the spinal cord, commonly 

 called the spinal marrow. 



The cervical vertehrce have a body and three projections, or 

 processes, one process standing out from each side, and one from 

 the upper side, called the superior spinous process. The atlas, 

 or first cervical vertebra, has no body nor superior spinous 

 processes, but the transverse processes are very broad. The 

 second is called the dentata, or tooth -like vertebra, because it 

 has a tooth-like projection which unites it with the atlas. The 

 other bones of the neck are very much alike. The bones of 

 the neck admit of very great motion, and are worked by 



