452 THE HORSE. 
laminal branch which passes through the foramen in the ala of the os 
pedis, and supplies the lamina. Thus the whole of these structures are 
full of blood-vessels, for not only are the arteries above described ramifying 
thus extensively upon them, but the blood is returned by corresponding 
veins. 
THE PEDAL AND NAVICULAR BONES have been minutely described at 
pages 324-5, but there are also two cartilaginous plates at the back of 
each ala of the pedal bone, which are of considerable importance. These 
have been called by the late Professor Coleman the lateral and inferior 
cartilages, whilst others have given them the name of the true and false. 
The lateral cartilages extend backwards and outwards from the posterior 
and upper borders of the coffin or 
pedal bone. They are united in 
front with the expanded termina- 
tions of the extensor tendon, and 
by cellular membrane with the lower 
end of the os corone. Posteriorly 
they wind upwards around the ala 
of the pedal bone, to which they 
are firmly fixed, forming the founda- 
tion for the heel. But in addition 
to these lateral or true cartilages, 
there are also two others, of a fibro- 
cartilaginous nature, which com- 
mence from the sides of the former 
and proceed forwards towards the 
heels of the pedal bone, and spread 
inwards upon the surface of the 
tendo-perforans. They are scarcely 
worthy of being described as dis- 
tinct cartilages, and appear more 
like ordinary condensed cellular 
membrane. 
It will thus be seen that the foot 
of the horse is a most complicated 
Tic. 6.—VIEW OF THE ARTERIES OF THE Froe 
AND Souk INTECTED: structure, which is liable to de- 
A. Lower porous surface of pedal bone. rangement whenever the hoof or 
B. Lateral surface of pedal bone. . arise 3 : 
C. ©. The plantar veins. horny case is interfered with, and 
D. D. The plantar arteries. this may occur either from mis- 
Kk. Lateral cartilage contracted by drying. E s : 
F. Veins of the frog, injected. management in shoeing, causing 
mechanical injury, or from inflam- 
mation of the secreting surface, which will end in the formation of imperfect 
horn, or from punctures or other wounds of the foot. Perhaps jn no organ 
does an injury so soon produce a return at compound interest, for the 
inevitable first result is a malformation of the hoof, and this again only adds 
to the original mischief. Hence it is that in the foot, more than in any other 
part even, prevention is better than cure, for in many of its diseases it 
happens that a cure cannot be obtained without rest; and yet it is also 
the fact that the secretion of horn will not go on perfectly without the 
stimulus of necessity afforded by exercise. The position of the leg is such 
that its veins have a hard task to perform at all times in returning the 
blood from the feet, but when the horse is not exercised at all they become 
doubly sluggish, and congestion in tliem is almost sure to occur. 
