The median nerve is one of the main nerves of the arm, which runs down the arm's full length into the hand; it is a branch of the brachial plexus.

The median nerve controls the muscles of the forearm and hand, which carry out bending movements of the wrist, finger, and thumb, and which rotate the forearm palm-inwards. This nerve also conveys sensations from the thumb, index finger, middle finger, part of the ring finger, and the region of the palm at the base of these digits.