The Framework of the Body 



37 



the two bones of the forearm, and is so called from its 

 resemblance to the spoke of a wheel. It is on the same 

 side as the thumb. Its slender upper end articulates 

 with the ulna and humerus ; its lower end is wider and 

 gives attachment in part to the bones of the wrist. This 

 bone radiates or ., 



turns on the II: 

 ulna, carrying 

 the hand with it. 



Experiment 14. 

 Rest the forearm 

 on a table, with 

 the palm up (an 

 attitude called 

 supination). The 

 radius is on the 

 outer side and par- 

 allel with the ulna. 

 If now, without 

 moving the elbow, 

 we turn the hand 

 (pronation) as if 

 to pick up some- 

 thing from the 

 table, the radius 

 may be seen and 

 felt crossing over 

 the ulna, while the 

 latter bone has 

 not moved. 



FIG. 23. Bones of the Hand and Wrist, as shown 



by an X-Ray Photograph. 

 (Two rings are plainly shown.) 



/ 53. The Hand. The hand consists of twenty-seven sepa- 

 rate bones, and is divided into three parts, the wrist, the 

 palm, and the fingers^ 



The carpus, or wrist, consists of eight bones, arranged in 

 two rows of four each, and bound together with ligaments 

 which admit of ample flexibility. Thus the wrist is much 



