THE REASONED EQUITATION 



hand, permits four motions, extension, flexion, lateral 

 inclination, and circumduction. Its movements are 

 given by the muscles of the neck, obliquus capitis, 

 sterno-maxillaris, rectus capitis, scalenus, longus coll, 

 splenius, and angularis scapula. All these muscles are 

 either attached or related to the three other muscles 

 which work the lower jaw. They are, therefore, 

 most intimately concerned in the position which is 

 given to the head and neck, through the sensation 

 of the bits on the bars. It is the position of the 

 head and neck which is the object of the flexions. 

 Two other especially powerful muscles of the 

 neck are concerned primarily with locomotion. 

 The rhomboideus is connected at the atlas region 

 with the other muscles of the head and neck; but 

 when this atlas region is fixed, it draws the 

 shoulder forward and upward. It is, therefore, 

 related to the scapulo-angularis and latissimus 

 dorsi of the chest. The other large muscle, the 

 mastoido-humeralis, has also one of its ends at the 

 atlas region, and the other at the shoulder and 

 chest. When the atlas region is fixed, at the same 

 time that the rhomboideus lifts the fore leg, the 

 mastoido-humeralis carries it forward. But if the 

 chest region is the fixed point, this muscle draws 

 the head and neck to one side. It is by means of 

 the flexions that we obtain for these two muscles 

 the fixed point in the atlas region. When the horse 

 accepts contact of the bits on the bars, the rider 

 controls directly the muscles of the head, and 



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