radial nerve

In biology, the nerve in the upper arm. Nervous impulses to regulate the function of the muscles which extend the arm, the wrist, and some fingers pass along these nerves. They also relay sensation to parts of the arm and hand. The radial nerve arises from the brachial plexus (network of nerves supplying the arm) in the armpit and descends the upper arm before dividing into the superficial radial and interosseous nerves.