152 



THE STRUCTURE OF THE HORSE 



ening (extension) only in one plane; and (2) the radius, 

 which turns or rotates in a peculiar way round the 

 former, carrying the hand with it, and thus enabling 

 the palm or the back of the hand to be turned upper- 

 most at will — motions described as ( supination ' and 

 c pronation.' In the horse there is nothing of the kind ; 

 the radius is a strong bone of almost equal size at both 

 ends, and the ulna is reduced to its upper part, which 

 is firmly fixed to the radius, its only function being to 

 strengthen the very perfect hinge of the el bow- joint 

 behind. The hand is thus permanently fixed in the 

 prone position, with its dorsal surface turned forwards. 

 A flexible and revolving wrist-joint, though essential 

 to the performance of the duties required from the 

 human hand would be quite incompatible with those 

 needed from the corresponding part of the horse. 



The consolidation of parts into a single supporting 

 column, so conspicuous in the forearm, is carried out to 

 a still greater extent in the last segment of the limb 

 of the horse. The eight carpal bones of the human hand 

 are, it is true (with one exception, the trapezium, the 

 inner bone of the distal or lower row, which supports 

 the thumb), all present, even to the pisiform, which pro- 

 jects backwards from the others on the outer side of the 

 wrist. These bones are, however, more solidly com- 

 pacted together than in the human hand, the flat sur- 

 faces by which they come in contact scarcely allowing 



