The radial nerve

Radial nerve · nervus radialis

The nerve that straightens your elbow, wrist and fingers.

What it does

The radial nerve winds around the back of the humerus in a shallow groove, then travels down the outer forearm. It powers the triceps and all the muscles that lift the wrist and straighten the fingers and thumb, and carries feeling from the back of the hand.

Surprising fact

Falling asleep with your arm draped over a chair back can squeeze this nerve against the humerus and cause a temporary "wrist drop", nicknamed Saturday night palsy.