678 



A MANUAL OF VETERINARY PHYSIOLOGY 



be restored by pressure, but that pressure must be ground 

 pressure. It is possible by means of a bar-shoe to throw con- 

 siderable pressure on the pad and heels, but the foot still con- 

 tracts ; it is only when the pad is bearing on the ground that it 

 continues in a healthy condition, and retains its normal size. 

 Foot-pad pressure is, therefore, one of the rules in shoeing if the 

 part is to be able to exercise its natural functions. In thinking 

 of the foot-pad as a buffer, sight must not be lost of the fact that 



Fig. 239. — Horizontal Section through the Structures of the Foot 

 Parallel to the Ground and Two Inches above it. 



The plantar cushion, I, 1, practically occupies half the foot, and is lodged between 

 2, 2, the lateral cartilages : these may be seen extending forward and attached 

 to the wing of the pedal bone at 6 ; they end posteriorly at 3, fusing with the 

 plantar cushion ; 4, cut surface of perforans tendpn ; 5, cut surface of the 

 navicular bone ; 7, the pedal bone ; 8, the white line, extending around the 

 wall from heel to heel ; 9, the wall : note the difference in thickness between 

 the toe and the heel ; 10, the vascular laminae. 



it affords protection to the joints and flexor tendon of the foot, 

 matters of vital importance. The position of these relative to 

 the foot-pad is seen in Fig. 220. 



Use of the Lateral Cartilages. — Those functions of the lateral 

 cartilages which have already been referred to may be sum- 

 marised as follows : These structures form an elastic wall to the 

 sensitive foot, and attachment to the vascular laminae ; they also 



