ELEMENTS OF BIPPOLOOY. 97 



CHAPTER VI.I. 



THE BACK. 



The back is mainly of interest because it furnishes the posi- 

 tion of the saddle, and it is necessary to know something of its 

 anatomy to be able to place the saddle and its load so they will 

 not injure it. 



The bones of the back are eighteen vertebrae of the spinal 

 column, and the ribs. The first eight of these vertebrae, with 

 their muscular coverings, are called, taken collectively, the 

 withers The upper spines of six or seven, usually, of these 

 bones are much longer, as can be seen in Figure 67, than on any 

 of the others, and they furnish points of attachment for the sus- 

 pensory ligament of the neck and for several important muscles 

 of the back, shoulder, and ribs. 



In front of the haunch-bone are six vertebrae, called the 

 lumbar vertebrae ; they slope towards the front. All the verte- 

 brae of the back are well padded with muscles on the sides, but 

 are very close to the skin on top, and these upper extremities 

 must be very carefully protected from any pressure. 



Looking at Figure 66, the muscles of the back are seen to be 

 broad and long. These muscles have slight motions; they are 

 several inches thick, and are admirably adapted to receive the 

 saddle and its load, provided the load is kept off the spinal 

 column and is evenly distributed. 



On each side of the withers, a little lower than their crest, 

 lie the upper ends of the shoulder-blades. These bones are 

 tipped with a broad, thick band of cartilage — indicated in Figure 

 67 — to protect the bone itself from injury. 

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