THE MUSCLES. 221 



head on which it turns, without any motion of the humer- 

 us ; and as the bones of the wrist are attached to the 

 lower end of this bone alone, and not to the ulna, c, 

 when the radhis revolves, the whole hand turns with it. 

 The alternate rolling motion is called pronation and supi- 

 nation. 



688. Motions of the Fingers. The motions of the 

 fingers do not merely result from the actions of the large 

 muscles, which lie on the forearm, these being concerned 

 more especially in the stronger actions of the hand. 



689. The finer and more delicate motions of the fingers 

 are performed by small muscles, situated in the palm and 

 between the bones of the hand, and by which the fingers 

 are expanded, and moved in all directions with wonderful 

 quickness. 



690. These are the organs which give the hand the 

 power of performing all its nicest motions, and by which 

 we are enabled to execute our finest works ; such as en- 

 graving, writing, sewing, and painting ; in all these cases- 

 the motions are directed by the will, while the instrument 

 is guided by the eye. 



691. The Thumb. The thumb is the antagonist to the 

 fingers. On the length, strength, free lateral motion, and 

 perfect mobility of the thumb, depends the power of the 

 human hand. Without the fleshy ball of the thumb the 

 power of the fingers would avail nothing ; and according- 

 ly, the large ball, formed by the muscles of the thumb, is 

 the distinguishing character of the human hand, and espe- 

 cially that an of an expert workman.* 



692. The Fingers of different Lengths. Although the 

 fingers are of different lengths, yet when they are doubled 

 into the palm, their ends become parallel. This is owing 

 to their difference of length being chiefly in the first rank 



To what bone is the wrist attached ? By what organs are the finer and 

 more delicate motions of the hand performed ? What is said of the im- 

 portance of the thumb to the perfection of the hand ? 



Bell, on the Hand. 



19* 



