190 



Diseases of the Horse. 



toe to heel, and shows the bones in their natural position 

 in the healthy hoof. 



FIG. 21. — A SECTION OF THE HORSE'S FOOT. 



Commencing above, the letter D indicates the lower end 

 of the long pastern bone; b is the coronary bone, which lies 

 internally from the upper or coronary border of the wall 

 of the hoof; c is the coffin bone, or foot bone, os pedis; 

 d is the navicular bone, a small bone of very great interest 

 to the surgeon, because injury and inflammation of surface 

 tissues is a very frequent cause of lameness, producing that 

 condition called " grogginess/^ The navicular bone bears 

 no part of the weight, but is apparently inserted for the 

 purpose of giving increased leverage power to the long 

 tendon, e, which passes from the coffin bone backward, 

 over the navicular bone and up the leg. 



It will be seen that from the upper part of the long 

 pastern bone 'to the end of the coffin bone is a straight 

 line, inclined at an angle of about 45° to the surface of the 

 ground. This obliquity of position enables the bone to act 

 as a spring, for the purpose of modifying concussion. 



