THE BONY FRAMEWORK 



The radius is fastened to the ulna in such a 

 manner that it can glide partly round it. This 

 gives us the power of twisting the hand. 



Experiment 10. To illustrate the action of the radius. 

 Rest the forearm on a table, with the palm up. The 

 radius is on the outer side (thumb) and parallel with 

 the ulna. If now, without moving the elbow, we turn 

 the hand as if to pick up something from the table, the 

 radius may be seen and felt crossing over the ulna, 

 while the latter bone has not moved. 



FIG. 21. The 

 Humerus. 



49. The Hand. The hand consists of the 

 eight bones of the wrist (carpal), the five 

 long bones of the palm (metacarpal), and the 

 fourteen small bones of the fingers 

 (phalanges). Each finger has 

 three bones, each thumb two. The 

 bones of the fingers are arranged 

 in three rows, as shown by closing 

 the hand. 



The twenty-seven bones of the 

 hand are held in place by strong but flexible 

 ligaments. By this beautiful contrivance, the 

 greatest strength and mobility are given to 

 the hand, which is thus fitted for all kinds of 

 work, from grasping heavy hammers to han- 

 dling the pen, playing difficult music on the 

 piano, and threading the finest needle. 



THE BONES OF THE LOWER LIMBS 

 50. The Lower Limbs. The general struc- 



ture and number of the bones of the lower limbs 



FIG. 22. The 

 Ulna and the 



bear a striking similarity to those of the upper Radius. 



