68 



THE HUMAN BODY 



support for the body has sacrificed its prehensile structure almost 

 altogether; the toes are less flexible than the fingers and the great 



FIG. 33. Diagram showing the relation of the pectoral arch to the axial skeleton. 



toe cannot be opposed to the others. A special modification of 

 the foot for its particular function is seen in the arching of the 

 instep. As Fig. 35 shows the bones of the foot form a springy arch, 

 ^^^^^^ the points of contact with the ground 



^r ^^^ being at the extremity of the heel 



f \^^ bone (os calcis, Ca of figure), and the 



^j^ J : distal ends of the metatarsals. The 

 ^^^^Jb*S bones of the leg are mounted upon 



the crown of the arch ( Ta of figure). 



FIG. 34. Diagram showing the ., 01 i 



attachment of the pelvic arch to Peculiarities of the Human Skele- 



ton. These are largely connected 



with the division of labor between the fore and hind limbs re- 

 ferred to above, which is carried farther in man than in any other 

 creature. Even the highest apes frequently use their fore limbs 



Cl 



M5 



Cli 



FIG. 35. The bones of the foot. Ca, calcaneum, or os calcis; Ta, articular surface 

 for tibia on the astragalus; N, scaphoid bone; CI, CII, first and second cuneiform 

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



in locomotion and their hind limbs in prehension, and we find ac- 

 cordingly that anatomically they present less differentiation of 

 hand and foot. The other more important characteristics of the 

 human skeleton are correlated for the most part with the mainte- 



