30 



ANIMAL PHYSIOLOGY. 



which is much slenderer above than at its lower end, and 

 supports the hand, is bound to the ulna at its upper end 

 by an orbicular ligament, which permits it to rotate with- 

 in its grasp, and is fastened to it below in such a way 

 that it revolves round that bone as on a pivot, carry- 

 ing with it the hand, and accomplishing pronation and 

 gupination, or the turning of the palm downwards and 

 upwards. 



The hand consists of eight 

 little carpal bones arranged 

 in two rows, five metacarpal 

 bones, which form the skeleton 

 of the palm, and the phalanges 

 or finger bones, of which the 

 thumb has two, and the other 

 digits three each. 



The bones of the upper row 

 of the carpus are named 

 beginning at the outer or 

 thumb side the scaphoid, 

 semihmar, and cuneiform 

 bones, and the pisiform, 

 smaller than these, and arti- 

 culated in front of the' cunei- 

 form. The bones of the second 

 row are called trapezium, tra- 

 pezoid, os magnum, and unci- 

 form, the unciform supporting 



Fig. 12. FKONT VIEW OF THE 

 BONES OF THE HAND, a, 



the metacarpal bones of the 

 ring and little fingers, and 



trapezium; 6, scaphoid, _and, the - others Sup p rting one 



beneath it, the trapezoid; c, 

 semilunar, and, beneath it, os 

 magnum; d, pisiform; e, cunei- 

 form; /, unciform. 



metacarpal bone each. 



The movements of the wrist 



are accomplished partly by 

 movement of the upper row of carpal bones on the radius, 

 and partly by one row of carpal bones moving on the other. 

 There is little perceptible movement allowed between the 

 carpal bones of the second row; but it is not without import- 

 ance that they are separate bones; for when we lean or push 

 with the palm, and the wrist is over-extended, the members 



