82 TEE HUMAN BODY. 



ulna ; the five metatarsal bones to the five metacarpal, and 

 the phalanges of the toes to those of the thumb and fingers. 

 On the other hand, there is in the arm no separate bone 

 at the elbow-joint corresponding to the patella at the knee, 

 but the ulna bears above a bony process, the olecranon (0, 

 Fig. 32), which at first is a separate bone and is the rep- 

 resentative of the patella. There are in the carpus eight 

 bones and in the tarsus but seven. The astragalus of the 

 tarsus (Ta, Fig. 35) represents however, two bones which, 



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

 eton. 



have grown together. The elbow-joint bends ventrally and 



the knee-joint dorsally. 



Comparing the limbs as a whole, greater differences come 



to light, differences which are 

 mainly correlated with the 

 different uses of the two 

 limbs. The arms, serving as 

 prehensile organs, have all 

 their parts as movable as is 

 consistent with the requisite 



FIG. Si-Diagram showingthe attach- Strength, while the lower 



SSJtS. thepelvicarcht theaxial limbs, having to bear the 



whole weight of the Body, 



require to have their parts much more firmly knit together. 

 Accordingly we find the shoulder girdle, represented red in 

 the diagram (Fig. 33), only directly attached to the axial 

 skeleton by the union of the inner ends of the clavicles with 

 the sternum, and capable of considerable independent move- 

 ment, as seen, for instance, in " shrugging the shoulders." 

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



