82 THE HUMAN BODY. 



The pelvic arch, on the contrary, is firmly and immovably 

 fixed to the sides of the sacrum. The socket of the scapula, 

 into which the head of the humerus fits, is very shallow and 

 allows a far greater range of movement than is permitted by 

 the deeper socket on the pelvis, into which the head of the 

 femur fits. Further, if we hold the right humerus tightly 

 in the left hand and do not allow it to move, we can still 

 move the forearm bones so as to turn the palm of the hand 

 either up or down: no such movement is possible between 

 the tibia and fibula. Finally, in the foot the bones are much 

 less movable than in the hand, and are arranged so as to make 

 a springy arch (Fig. 38) which bears behind on the calcaneum, 

 Ca, and in front on the distal ends of the metatarsal bones, 

 Os ; over the crown of the arch, at Ta, is the surface with 



Sfhl 



FIG. 38. The bones of the foot. Ca, calcaneum, or os calcis ; Ta. articular sur- 

 face for tibia on the astragalus ; N, scaphoid bone ; CL CII, first and second 

 cuneiform bones ; Cb, cuboid bone ; Ml, metatarsal bone of great toe. 



which the leg-bones articulate and on which the weight of 

 the Body bears in standing. 



The toes, too, are far less movable than the fingers, and 

 this difference is especially well marked between the great 

 toe and the thumb. The latter can be made to meet each of 

 the finger-tips and so the hand can seize and manipulate very 

 small objects, while this power of opposing the first digit to 

 the rest is nearly absent in the foot of civilized man. In 

 children, however, who have never worn boots, and in savages, 

 the great toe is far more movable, though it never forms as 

 complete a thumb as in many apes, which use their feet, as 

 well as their hands, for prehension. By practice, however, 

 our own toes can be made much more mobile than they 

 usually are, so that the foot can to a certain extent replace 

 the hand; as has been illustrated in the case of persons born 



