BONES AND MUSCLES OF THE FOOT. 
487 
than those of the carpus, and some of them of considerable 
size. The articulation with the leg is formed by one of these 
only, the astragalus ,, which projects above the rest, and is im¬ 
bedded between the projecting extremity of the tibia (which 
forms the inner boundary of the ankle-joint) and that of the 
fibula. The astragalus rests on the os colds or bone of the 
heel, which projects considera¬ 
bly backwards, and is connected 
in front with the other bones of 
the tarsus. In front of the 
tarsus we find the metatarsus, 
composed of five long bones, 
which in man are all attached 
to each other, but of which one 
is separate in the Quadrumana, 
in order to give freer play to 
the great toe, the action of which 
resembles that of the thumb. 
The toes, like the fingers, are 
composed of three phalanges 
(with the exception of the 
great toe, which has only two); 
these are in Man much shorter 
than those of the hand, and 
are evidently not adapted for 
prehension ; but in many of the 
Quadrumana, their length is 
nearly equal to that of the 
fingers, and the great toe is as 
opposable as the thumb. The 
foot is far from being thus con¬ 
verted, however, into a perfect 
hand; but it becomes a very 
useful instrument for clasping 
the small branches and twigs 
of the trees among which these 
animals live. The foot of Man 
is distinguished from theirs, by 
its power of being planted flat upon the ground, and thus 
affording a firm basis of support. Even the Chimpanzee 
and the Orang, when they attempt to walk erect, rest upon 
Fig. 230,— Muscles of the Sole of 
the Foot (Middle Layer). 
1, accessory of the long flexor of the 
toes; 2, tendon of the long flexor 
issuing from its sheath; 3, tendon 
of the long flexor of the great toe; 
4, first lumbricalis ; 5, tendon of 
the superficial flexor, divided be¬ 
hind its perforation; 6, short flexor 
of the little toe ; 7, short flexor of the 
great toe; 8, portion of the oblique 
abductor of the great toe ; 9, poste¬ 
rior extremity of the fifth metatar¬ 
sal bone; 10, sheath of the long pero¬ 
neal; 11, os calcis, or bone of the 
heel. 
