BONES 159 



hung. The bone in front is slender and long and is called 

 the collar bone, or clavicle. Its inner end rests against the 

 breast bone. The bone behind is flat and forms the shoul- 

 der blade, or scapula. It is not joined to any bone, but 

 is hung only by muscles. These two bones form the 

 shoulder. 



315. The arm. From the side of the shoulder a long, 

 strong bone hangs down to form the frame of the arm 

 above the elbow. It is called the humerus. At the elbow 

 it joins two other bones which form the frame of the arm 

 below the elbow. The bone upon the thumb side of the 

 arm is called the radius, and upon the little finger side, 

 the ulna. 



316. The wrist and hand. At the ends of the radius 

 and ulna are eight small, rounded bones which form the 

 wrist. These bones are firmly joined together by con- 

 nective tissue like the tarsal bones of the foot. They 

 make the wrist more springy than it would be if it were 

 a single bone. 



At the lower end of the wrist are nineteen slender bones, 

 joined end to end so as to form five strings of bone as in 

 the foot. The first bones of each string are buried in the 

 flesh and make the frame work of the palm of the hand. 

 The outer bones of each string form the fingers. 



317. Hand and foot compared. The hand and foot are 

 each made of the same number of bones and upon the 

 same plan. The instep is much larger and stronger than 

 the wrist, for it must bear great weights. The toes are 

 much shorter than the fingers, but they have the same 

 muscles and can be moved in the same ways. The great 

 toe cannot be turned in so as to be brought against the 

 other toes as the thumb can against the fingers. The 

 foot would be a very clumsy hand, yet some persons who 



