THE SPINE AND BACK 245 



THE SPINE AND BACK. 



The spine, or back, consists of a cliain of bones from tlic poll to tl)f 

 extremity of the tail. It is made up of twenty-three bones from the neck 

 to the haunch ; eighteen, called dorsal vertebrae, composing the back ; and 

 five, lumhar vertehroe, occup}'ing the loins. On this part of tlie animal the 

 weight or burden is laid, and thei'e are two things to be principally con- 

 sidered, easiness of carriage and streng-th. If the back were composed of 

 unyielding materials — if it resembled a bar of wood or iron, suchjarrin"" 

 and jolting, in the rapid motion of the animal, could not possibly be endui'ed. 

 In order to avoid this, as well as to assist in turning, the back is divided 

 into numerous bones ; and between each parr of bones there is interiiosed 

 a cartilaginous substance, most highly elastic, that Avill jield and give way 

 to every jar, not so much as to occasion insecurity between the bones, or 

 to permit considerable motion between any one pair, but forming altoo-ether 

 an aggregate mass of such perfect elasticity that the rider sits almost 

 undisturbed, however high may be the action or however rapid the pace. 



Strength is as important as ease ; therefore the bones are united 

 together -with peculiar firmness. The round head of one is exactly fitted 

 to the cup or cavity of that immediately before it ; and between them is 

 placed the elastic ligamentous substance which has been just described, 

 so strong, that in endeavouring to separate the bones of the back they 

 win break before this substance will give way. In addition to this thci-e 

 are ligaments running along the broad under-surface of these bones — 

 ligaments between each of the transverse processes, or side projections of 

 the bones — ligaments between the simious processes or ujiright projections, 

 and also a continuation of the strong ligament of the neck running alono- 

 the Avhole course of the back and loins, lengthening and contractino-, as in 

 the neck, with the motions of the animal, and forming a powerful bond of 

 union between the bones. 



By these means the hunter will carry a heavy man -without fatigue or 

 strain through a long chase ; and those shocks and jars are avoided which 

 would be annoying to the rider and injurious and speedily fatal to the 

 horse. 



These provisions, however, although adequate to common or even severe 

 exertion, -will not protect the animal from the consequences of brutal usao-e ; 

 and, therefore, if the horse is much overweighted, or violently exercised 

 or too suddenly pulled upon his haunches, these ligaments are strained. 

 Inflammation follows. The ligaments become changed to bone, and t'ae 

 joints of the back lose their springiness and ease of motion ; or rather, in 

 point of fact, they cease to exist. On account of the too hard service re- 

 quired from them, and especially before they had gained their full streno-th, 

 there are few old horses who have not some of the bones of the back or 

 loins ancliylosecl — united together by bony matter and not by ligament. 

 When this exists to any considerable extent the horse is not pleasant to 

 ride ; he turns with ditticulty in his stall, he is unmlling to lie down, and 

 when down to rise again, and he has a singular straddhng action. Such 

 horses are said to be hrolien-liaclcecl or chinked in the hack. 



The length of the back is an imj^ortant consideration. A long-backed horse 

 will be easy in his paces, because the increased distance between the fore 

 and hind legs, which are the supports of the sjiine, will afford greater room 

 for the play of the joints of the back. A long spring has much more play 

 than a short one, and will better obviate concussion. A long-backed horse 

 is likewise formed for speed, for there is room to bring his hinder lees 

 njore luider him in the act of galloinng, aud thus more powerfully propel 



