OUTLINE OF THE STKUCTUEE OF THE HORSE. 29 



legs, the hips, and parts of the jaws. These are the largest 

 and strongest in the body, as they need to be, in order to 

 resist the great strain and pressure to which they are con- 

 stantly subject. The spongy bones include the ends or heads 

 of all the bones that articulate to form the joints ; the entire 

 number of small bones that form the joints; the shoulder- 

 blades, the ribs, and the upper and back portions of the 

 maxillaries, or jaw-bones. The spongy portions are those in 

 which disease and exostosis, or enlargement, nearly always 

 make their appearance. 



The entire movements of the body and limbs, with a few 

 trifling exceptions, are effected by the agency of that pe- 

 culiar substance known in our butchers' shops as flesh, and 

 which is recognized by anatomists as muscular tissue. This 

 constitutes the chief bulk of the soft parts outside the three 

 great cavities of the body (the cranial, thoracic, and abdom- 

 inal). They possess great power of motion, being composed 

 of numberless little strings, or fibers, each of which has a 

 contractile and elastic power of itself, the whole being so ar- 

 ranged as best to serve the purpose intended. "While each 

 fiber has an independent elasticity, it acts, at the same time, 

 in conjunction with all the others in the muscle of which it 

 forms a part, so that their united power becomes very great. 

 This may be realized when we consider that it is they which 

 give to the horse his immense strength. One very noticeable 

 feature in the anatomy of the muscles is the albuminous 

 coating which surrounds each fiber, and thus prevents fric- 

 tion. It fills the interstices throughout the muscle, all whose 

 parts are united and bound together by means of its sticky, 

 waxy qualities, with the strength of " a three-fold cord which 

 can not be broken." 



Each muscle terminates in a more solid, compact, whitish 

 substance, commonly called a cord. Such it really is, acting 

 with reference to the joint in the same manner as the cord 

 to a pulley. (See description under heading, The Tendons.) 



9 



