488 BONES AND MUSCLES OF THE FOOT. 
the side of the foot ; and the absence ef a projecting hee 
causes them to be very deficient in the power of keeping the 
leg upright upon it. For it is to this projection that the 
strong muscles of the calf of the leg are fixed, by which the 
heel is drawn upwards or the leg drawn back upon it. Othe 
muscles at the side and back of the leg, the direction of whos 
tendons is changed by a sort of pulley at the ankle-joint 
aided by the muscles of the foot itself, serve to bend the toes 
—an action which gives great assistance in walking, running 
leaping, &c. And the toes are straightened by an extenso: 
muscle, which lies on the front of the leg, and of whicl 
the tendon runs under an annular ‘ligament that encircle 
the ankle, and is then divided and spread-out to th 
toes, over the upper surface of the foot. The great toe i 
a very important instrument in the act of walking, sine 
much of the spring forwards is given by the bending o 
its phalanges ; and it is provided with two flexor muscle 
of its own. 
649. On the internal side of the foot, the bones of th 
tarsus and metatarsus form a kind of vault.or arch, whicl 
serves to lodge and protect the «vessels and nerves tha 
descend from the leg towards the toes. This arch furthe 
serves the important purpose of deadening the shock tha 
would otherwise be experienced every time that the foot i 
put to the ground; for, by the elasticity of the ligament 
which hold together the bones that compose it, a sort 0 
spring is formed, which yields for a moment to the shock 
and then recovers itself. We feel the difference which thi 
makes, when we jump from a height upon our heels ; the ja 
is then propagated directly upwards from the heel to the leg 
thence to the thigh, and thence to the spinal column, and 1 
it were not from the peculiar manner in which this is con 
structed ($ 631), a-severe shock of this kind might produe 
fatal effects by concussion (or shaking) of the brain. h 
animals which walk upon four extremities, the difference oa 
direction in which the legs are connected with the spin 
prevents a jar from being propagated along the latter to : 
similar degree. But in those which are destined to obtai 
their food by sudden and extensive leaps, such as the animal 
of the Cat tribe (the Lion, Tiger, &c.), we find an arrange 
ment of the bones of the foot, well adapted to diminish th 
