The thumb-side forearm bone

What it does

The radius runs from the elbow to the thumb side of your wrist. At the elbow its head can spin, and at the wrist it carries most of the hand. When you turn a door key or flip your hand palm-up, the radius rotates around the ulna to make the movement possible.

Why it matters

Every time you use a screwdriver, pour a drink or turn a page, you are rotating your radius. That twisting movement is something few other animals can do as well, and it underpins much of what our hands can do.

Nearby

• The little-finger-side forearm bone
• The upper arm bone
• The scaphoid (wrist bone)
• The pronator teres
• The supinator

Read more

• Radius — Wikipedia