430 ANATOMY AND PHYSIOLOGY OF THE IIORSE’s FOOT. 
Nothing can be better adapted for these purposes than the 
vesicles of adipose tissue : consequently we find the plantar 
cushion abundantly supplied with this material where it is most 
needed — towards the posterior and inferior parts of the foot. 
The comparative anatomist will at once perceive that we 
have, in the elastic apparatus of the horse's foot, an arrange- 
ment not found in that of any other animal outside the family 
of solipeds, and which, though to some extent complicated — 
as the demands made upon the organ itself are complicated — 
is yet most admirably adapted to the requirements of this 
extremity of the limb, forming, as it does, one continuous 
structure surrounding its circumference, and protecting the 
most essential and vulnerable portion of its plantar face. 
To form a good estimate of its form and disposition, with a 
view to comprehend the part it plays in the economy of the 
foot, it has been suggested to remove the coronary and 
navicular bones, as well as the expansion of the deep flexor 
tendon, from the pedal bone, taking care, however, to leave 
the lateral cartilages and plantar cushion as intact as possible. 
The effect of this will be understood by referring to figure 3, 
representing a longitudinal section of the foot. It will then 
be observed that this resilient, suspensory, and weight- 
diffusing structure, in its entirety, together with the pedal 
bone, constitutes a kind of basin-shaped receptacle, partly 
bony, partly fibrous and fibro-cartilaginous. In front this 
cavity is bordered by the pyramidal process (fig. 9, i), and 
around it, and extending along the sides of the organ towards 
the heels, is the plantar cushion ; on each side are the large 
plates of cartilage (fig. 9, //), and, behind, the upper margin of 
the plantar cushion. It will also be observed that this composite 
surface offers two inclined planes, which are opposed to each 
other; these are situated, one before, the other behind. The 
first is the shortest and densest, and is formed by the articu- 
lating surface of the pedal bone (figs. 4 ,/; 9, h ) ; the second, 
or posterior, slopes in an opposite direction from behind to 
before, is the longest and by far the most extensive, and is con- 
stituted by the upper or front surface of the plantar cushion. 
On these two planes, then, inclined towards each other, 
and composed, as they are, of a diversity of materials bound 
together in the most admirable fashion, the whole weight of 
the body ultimately falls after its transmission through the 
rays forming the column of support, the last of which is 
imbedded in this bony, fibrous, and cartilaginous socket. The 
manner in which they distribute this weight, without im- 
pairing, in the slightest degree, the other functions of the 
foot, will be considered presently. 
