AND LEG OF THE HORSE. 
565 
ligaments to tlie os coroiicC, on which the large pastern bone in part 
rests; and thus, as Mr. Percivall shews, the elasticity of the sus¬ 
pensory ligament is communicated to another joint, which by the 
common observer would have been regarded as beyond its influence. 
The suspensory ligament thus affords to the fetlock a beautiful 
spring, and at the same time a firm and effectual protection to the 
joint. If we divide the flexor sinews, the animal will be able to stand 
without difficulty; but, if we likewise cut through the suspensor}^ 
ligament, the fetlock joint immediately comes to the ground; thus 
shewing that the principal use of the ligament is to support weight. 
“We find that in oxen the ligament is more than double the size 
of that of the horse, whilst the sinews are often smaller; but with 
an increased size we have a great decrease in elasticity. From this 
fact of comparative anatomy, we are disposed to conclude that the 
chief use of the suspensory ligament is to support the fetlock; an 
office as a spring which though highly important, is yet to be regard¬ 
ed as secondary. In the action of the limb, we find that a consider¬ 
able portion of the superincumbent weight rests upon the sessamoid 
bones, which, in consequence, recede and descend, or rather move 
backwards, like a door on its hinges, thus putting the ligament on 
the stretch : but, in order that they should not be strained too much, 
a limit is put to their action by the flexor tendons, which brace the 
sessamoid bones, and support the joint. Thus we see how important 
it is that the ligament should possess elasticity, and that the tendons 
should not. If the former were not elastic, we should lose an im¬ 
portant spring; and if the latter were so, they could no longer stay 
the action of the suspensory ligament. The tendons would also, 
by an elastic structure, be unfitted for the purpose of communi¬ 
cating motion to the muscles; for to do so, it would be necessary 
to put them on the stretch, before the latter could communicate the 
requisite motion to the foot. A similar effect would, indeed, be 
produced, as if we were to drive with India-rubber traces, in which 
a certain loss of power must be exhausted in overcoming the elas¬ 
ticity of the traces, before the vehicle could be put in motion. 
“ The Pastern Joint contributes towards the elasticity of the leg 
in proportion to its obliquity; this inclination taking off the weight 
from the bones, and throwing it upon the elastic parts behind. 
The large pastern bone, we have seen, rests in a great measure on 
a ligament, which, though not clastic itself, can act as such, from its 
connexion with the sessamoid bones and the suspensory ligament— 
thus affording a considerable spring. The small pastern bone rests, 
throughout its whole posterior surface, on the flexor perforans ten¬ 
don, and the latter, at this part, is embedded in, and supported by, 
the soft cushions of the heels, which recede at every step; thus 
aflbrding one of the most elastic s])rings in the whole body, though 
VOL. XIIT. 4 F 
