Take a look at one of your own arms. Notice how you can rotate your lower arm along the lengthwise axis in order to change the orientation of your hand. Similarly you can rotate your upper arm in order to change the orientation of your elbow.
Stretch your arm. Now you can use either of these rotations to rotate your hand, the only difference is that with the upper arm rotation the elbow will follow along, for the lower arm rotation it won't. So logically if you rotate the upper arm in one direction and the lower arm in the other direction only the elbow would rotate while the hand stay in place.
I just realized that I can't do that, if I stretch my arm and will my elbow to rotate while the hand stays in place nothing happens. But if I do the two operations one at a time I can actually achieve approximately 90 degrees difference in elbow orientation with the same hand orientation.
Am I the only person with this inability?
Stretch your arm. Now you can use either of these rotations to rotate your hand, the only difference is that with the upper arm rotation the elbow will follow along, for the lower arm rotation it won't. So logically if you rotate the upper arm in one direction and the lower arm in the other direction only the elbow would rotate while the hand stay in place.
I just realized that I can't do that, if I stretch my arm and will my elbow to rotate while the hand stays in place nothing happens. But if I do the two operations one at a time I can actually achieve approximately 90 degrees difference in elbow orientation with the same hand orientation.
Am I the only person with this inability?
