68 DISEASES OF THE HORSE’S FOOT 
accommodating as it does the frog-stay, preventing the 
tendency to backward movement becoming excessive, and 
directing the change of form to the sides. Where the 
greatest pressure is transmitted, then, is to the inner 
aspects of the flexible lateral cartilages. The coronary 
cushion being continuous with the plantar, the backward 
and outward movements of the latter will tend to pull upon 
and tighten the former, especially in front. This will 
account for the contraction noted by Lungwitz in the 
anterior half of the coronary edge of the hoof. 
Remove the body-weight, and naturally the elastic 
nature of the lateral cartilages and the coronary and 
plantar cushions, with, in a less degree, that of the hoof, 
cause things to assume their normal position. 
Repeat the weighting of the hoof, in this second case 
without frog-pressure, and we shall see at once that we have 
done away with one of the greatest factors in determining 
the outward and backward movements of the plantar 
cushion—namely, the pressure from below on its wedge- 
shaped mass. The movement of the plantar cushion will 
now be downwards as well as backwards; and, seeing that 
it is attached to the inner aspect of each lateral cartilage, 
we shall expect these latter, by the downward movement of 
the plantar cushion, to be drawn inwards. This Lungwitz 
has shown to occur. 
The chief function of the lateral cartilages, therefore, is 
to receive the concussion engendered by locomotion, which 
concussion is directed backwards and outwards by the pad- 
like plantar cushion. 
In addition to this, the lateral cartilages, together with 
the plantar and coronary cushions, play the part of a valve 
to the whole of the veins of the foot. 
It is in this way: We have only to refer to the chapter 
on anatomy to see that the whole of the foot is covered 
with a tissue of extreme vascularity. Thus we find papille 
over the coronary cushion; enlarged and modified papille 
—the sensitive lamine—covering the anterior face of the 
os pedis ; and numberless papille again covering the sole. 
