10/17/2026
There’s a twist to how your forearm works.
Your forearm has two bones: the radius and the ulna. When you rotate your palm from facing up to facing down, the radius crosses over the ulna.
That simple movement helps you turn a doorknob, pour a cup of coffee and use a screwdriver. A lot of coordination happening beneath the surface, without you giving it a second thought.
Be honest. You just looked at your arm and tried it.