X] 



THE OROAXS OF LOCOMOTION 



127 



The plantar cushion is a libi()eh\stic pad containing fatty 

 tissue and few vessels. It is continuous with the coronary 

 cushion. It is sometimes called the 'sensitive frog' and rests 

 upon the frog or foot-pad. The sensitive sole is the part above 

 the horny sole. 



The principal functions of the foot are three, (1) wear and 

 tear. (2) sup];)orting weight, and (3) warding off concussion. The 

 plantar cushion is especially constructed for the last of these 

 functions, but in common with the vascular part generally it 

 produces the horn which goes to form the hoof. 



The foot contains three bones, the os pedis or coffin bone, the 

 navicular which rests slightly on the os pedis and is held in 

 position by ligamentous tissue, and the os coronae, which onty 

 partly belongs to the foot. Above the os coronae, is the os 



Fig. 57. Horse's Foot (from Smith, Messrs Bailliere, Tindall and Cox). 

 1. OS coronae. 2. os pedis. 3. naviculae. 4. wall. 5. sole. 6. fi"Og. 

 7. plantar cushion. 8. perforans tendon. 9. wall-secreting sub- 

 stance. 10. extensor pedis tendon. 11. junction of wall and sole. 



sufifraginis which articulates with the cannon bone, but neither 

 of these bones belong to the foot. The pedal bone does not 

 occupy the whole of the interior of the hoof but its place is taken 

 on either side by a plate of lateral cartilage. The two lateral 

 cartilages which reach high above the level of the hoof are 

 attached to the pedal bone. 



The navicular supplies a yielding articulation to the os 

 coronae, since the latter bone rests partly on the navicular and 

 only partly on the pedal bone. A direct concussion of the pedal 



