Our skeleton is amazingly designed. Let’s take a look at the arm. The upper part of your arm is made of one bone, the humorous. The lower part of your arm has two bones, the ulna and the radius. The ulna is on your pinky finger side, while the radius is on your thumb side. These two bones are able to twist, with the radius rotating while the ulna stays put. Hold out your arms and twist them. ...
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