ANATOMY AND PHYSIOLOGY OF THE HORSE'S FOOT. 177 
uninterruptedly the circulatory and nutritive functions of the 
organ, even when it is subjected to great pressure and danger 
of injury from concussion against the ground, and in power- 
fully co-operating to avert shock to the whole limb by evenly 
distributing the weight which is suddenly, and oftentimes 
even violently, thrown upon it ; while it is, above all, beau- 
tifully adapted to facilitate long-continued speed, and, with 
its appendages, that which is most of all necessary in an 
organ from which so much is required — elasticity. 
In the horse of six years old, with a healthy well-formed foot 
— one which has not been tampered with by the unskilful 
farrier, or which has not been subjected to the gross mis- 
management with which we are so familiar — we find the 
most favorable subject for examination. In such a foot the 
lower surface of the os pedis is seen to be of a crescent shape 
(fig. 5), the convexity being directed forwards, and the con- 
cavity towards the posterior part of the organ. Springing 
upwards from the convex border, and receding at an angle 
of from 50° to 60° in front, we have the face or largest 
surface of this bone, and that to which it mainly owes its 
shape. This antero-lateral face corresponds to the inner 
surface of the wall or crust of the hoof, preserving the same 
degree of obliquity as it does in the healthy foot ; it rises 
boldly until it culminates in a triangular peak immediately 
in front (th z pyramidal eminence , fig. 4, a), into the base of 
which is implanted the extensor tendon of the foot. From 
this eminence the upper border of the bone dips somewhat 
suddenly on each side, and, gradually declining, proceeds 
backwards to the two branches, wings, or horns of the 
crescent. 
Looking closely into the structure of this wide surface, 
there will be observed a diversity in the arrangement of its 
plates or fibres — if we may use such a term when speaking 
of a bone — which exhibits design and adaptation to an * 
eminent degree. These fibres appear to grow lengthways 
(from above downwards), in order to confer strength and 
resistance, and are, in the front and upper portions, closely 
bound together to form a compact exterior, which is slightly 
furrowed and perforated by grooves and minute openings for 
the reception and passage of blood-vessels that issue from the 
interior of the bone, or distribute themselves in the most 
wonderful manner over its face. Nearer* the lower margin 
of the os pedis these fibres open out, apparently with the 
object of gaining a wider superficies without adding to the 
weight of the bone, until, on reaching that border, they 
become so widely separated and thin, yet so interwoven one 
