34 THE ARTISTIC ANATOMY OF ANIMALS 



The antibrachial extremity of the humerus is flattened 

 from without inwards. It terminates in two articular 

 surfaces, which articulate with the radius and ulna. 



The olecranon process of the ulna being slightly developed, 

 it follows that the olecranon fossa is not large ; neither is 

 the coronoid. 



General View of the Form of the Forearm and Hand 



We now proceed to the study of the two regions of the 

 fore-limbs which present the greatest variety in regard to 

 the number of bones and also in regard to form and pro- 

 portions. These two regions are the forearm and the hand. 

 It is first of all necessary to say that in man, when the 

 fore-limb hangs beside the body, and the dorsum of the hand 

 looks backwards, the two bones of the forearm are parallel, 

 and that this position is known by the name of supination. 

 It is also necessary to remember that there is another 

 attitude, in which the radius, crossing the ulna, and carrying 

 the hand with it, displaces the latter in such a way that the 

 palmar surface looks backwards. This second position is 

 known as pronation. 



Let us now suppose that a man wishes to walk in the 

 attitude of a quadruped. It will be necessary, in order that 

 his upper limbs, being for the moment anterior ones, may act 

 as members of support, to place the forearm in pronation, in 

 order that, as is more normal, the hands may rest on the 

 ground by their palmar surfaces. In this position the radius, 

 being rotated on its own axis at its upper extremity and 

 around the ulna in the rest of its extent, shall have its 

 inferior extremity situated on the inner side of the corre- 

 sponding extremity of the latter. 



Such is the situation of the bones of the forearm and the 

 attitude of the hand in quadrupeds. In short, quadrupeds 

 have their anterior members in the position of pronation. 



The individual whom we have just supposed placed in the 

 attitude of a quadruped would be able to maintain this 

 position by pressing en the ground more or less extensive 

 portions of his hands ; the whole palm of the hand may 

 be applied to the ground (Fig. 22) ; or the fingers only — 



