566 DISEASES OF THE HORSE. 



pasterns and are called flexors^ because they flex, or bend, the pasterns 

 and coffin bone backward. One of the tendons is attached to the 

 upper end of the short pastern, while the other passes down between 

 the heels, glides over the under surface of the navicular bone, and 

 attaches itself to the under surface of the coffin bone. These two ten- 

 dons not only flex, or fold up, the foot as the latter leaves the ground, 

 during motion, but at rest assist the suspensory ligament in support- 

 ing the fetlock joint. 



The foot-axis is an imaginary line passing from the fetlock joint 

 through the long axes of the two pasterns and coffin bone. This 

 imaginary line, which shows the direction of the pasterns and coffin 

 bone, should always be straight — that is, never broken, either forward 

 or backward when viewed from the side, or inward or outward when 

 observed from in front. Viewed from one side, the long axis of the 

 long pastern, when prolonged to the ground, should be parallel to 

 the line of the toe. Viewed from in front, the long axis of the long 

 pastern, when prolonged to the ground, should cut the hoof exactly 

 at the middle of the toe. 



Raising the heel or shortening the toe not only tilts the coffin bone 

 forward and makes the hoof stand steeper at the toe, but slackens the 

 tendon that attaches to the under surface of the coffin bone (perforans 

 tendon), and therefore allows the fetlock joint to sink downward and 

 backward and the long pastern to assume a more nearly horizontal 

 position. The foot-axis, viewed from one side, is now broken for- 

 ward ; that is, the long pastern is less steep than the toe, and the heels 

 are either too long or the toe is too short. On the other hand, raising 

 the toe or lowering the heels of a foot with a straight foot-axis not 

 only tilts the coffin bone backward and renders the toe more nearly 

 horizontal, but tenses the perforans tendon, which then forces the fet- 

 lock joint forward, causing the long pastern to stand steeper. The 

 foot-axis, seen from one side, is now broken backward — an indication 

 that the toe is relatively too long or that the heels are relatively too 

 low. 



The elastic tissues of the foot are preeminently the lateral cartilages 

 and the plantar cushion. The lateral cartilages are two irregularly 

 four-sided plates of gristle, one on either side of the foot, extending 

 from the wings of the coffin bone backward to the heels and upward to 

 a distance of an inch or more above the edge of the hair, where they 

 may be felt by the fingers. Wlien sound, these plates are elastic and 

 yield readily to moderate finger pressure, but from various causes 

 may undergo ossification, in which condition they are hard and un- 

 yielding. The plantar cushion is a wedge-shaped mass of tough, 

 elastic, fibro-fatty tissue filling all the space between the lateral car- 

 tilages, forming the fleshy heels and the fleshy frog, and serving as a 

 buffer to disperse shock when the foot is set to the ground. It ex- 



