ANATOMICAL CONSIDERATIONS. 



43 



in a direction from the plummet line. The angularity of the two top- 

 most pieces can, however, not possibly escape notice; neither can the 

 slanting position of the pastern bones fail to attract attention. Noting 

 these peculiarities, the reader recognizes that the 

 bones of the fore extremity cannot be self-sus- 

 taining, but they must be upheld or retained in 

 their relative situations by the structures which 

 surround them in the living subject. 



The scapula and humerus, or the two topmost 

 bones, are rendered firm by the joint action of 

 the powerful extensor and flexor muscles apper- 

 taining to the shoulder. The pastern bones trans- 

 fer their weight to the strong tendon which passes 

 immediately under their lower surfaces. The other 

 bones are held in their situations by the energetic 

 contractility of the muscles which embrace them. 

 Hence it is obvious the rider, when seated on the 

 back of a horse, is not upheld by any osseous re- 

 sistance. His burden reposes upon living fiber. 

 The bone limits the sphere of contractility, and 

 thus gives firmness to the limbs ; but it endures 

 no portion of the weight. So exquisitely has na- 

 ture adapted her creature to its uses, that in the 

 horse man is provided with a means of convey- 

 ance remarkable for fleetness, but more wonderful 

 for the elastic and buoyant seat which an admi- 

 rable body affords to an ungrateful master. 



Had weight been cast upon bone, the shock 

 communicated by placing the foot upon the ground would have been so 

 powerful as must have made the saddle a seat of torture. This is no 

 speculative conjecture, but it is a deduction drawn from positive fact. 

 Hard work causes the pastern bones to quit the slant, which is their 

 natural position, and to assume a more upright direction. They very 

 rarely become actually perpendicular; but as they verge toward that 

 attitude, so as partially to transfer their weight from the tendon to one 

 another, the jar communicated to the rider becomes most distressing. 

 The tendons of the foreleg are, therefore, of all importance ; the utility 

 of these structures cannot be better illustrated than by appealing to the 

 terrible effects which ensue upon injury to these organs. 



However, that the reader may fully appreciate the simplicity and the 

 seeming complexity developed in the various arrangements exposed upon 

 dissection, the next illustration is inserted, against which numerous lines 



THE PRINCIPAL FLEXOR TEN- 

 , DONS OF THE FORIXEQ. 



1. The perforans. 2. The per- 

 foratus. 3, 4. Accessory muscles. 

 5, 6. Restraining ligaments. 7. 

 The pedal cartilage divided. 8. 

 The navicular bone. 



