24 HORSESHOEING. 



peculiar form, and, by their special power of contraction, 

 change the relative positions of the bones and thus make it pos- 

 sible for the animal to move. For this reason, the muscles are 

 called the active, and the bones the passive, organs of motion. 

 By carefully examining a muscle it will be found to consist of 

 actual, minute, reddish, muscular fibres. As a rule, muscles 

 terminate in more or less strong, glistening, fibrous cords called 

 tendons, or fibrous sheets tenned aponeuroses, by which they 

 are attached to the bones. In the limbs are muscles terminating 

 in very long tendons, which act as draw-lines upon the distant 

 bones of the foot (long and short pasterns and pedal bone) and 

 set them in motion. Such long tendons are enclosed in sheaths 

 of thin, membranous tissue, known as tendon sheaths. The 

 inner surface of such a sheath is in direct contact with the 

 surface of the tendon, and secretes a thin slippery fluid 

 (synovia) which lubricates the tendon and facilitates its gliding 

 ■udthin the sheath. 



As long as the bones, articulations, muscles, and tendons of 

 the limbs remain healthy, just so long will the legs maintain 

 their natural direction and position. Frequent!}^, however, 

 this normal condition of the limbs is gradually altered by dis- 

 ease of the bones, joints, and tendons, and defects in the form 

 and action of the lower part® of the limbs arise that often 

 require attention in shoeing. 



THE FOOT. 

 A. The Bones of the Foot. 



Since the horse is useful to man only by reason of his move- 

 ments, his foot deserves the most careful attention. The horse- 

 shoer should be familiar with all its parts. Fig. 3 shows the 

 osseous framework of the foot, consisting of the lower end of the 

 cannon bone (A), the long pastern (5), the two sesamoid bones 

 (C), the short pastern (D), and the pedal bone (E). The lower 

 end of the cannon, or large metacarpal bone (A) exhibits two 

 convex articular surfaces (condyles) separated by a median 

 ridge running from before to behind, and all covered by articu- 



