radialis

Radialis is a Latin adjective meaning “of the radius” and is used in anatomy to indicate a relationship to the radius bone or to the radial (thumb-side) aspect of the forearm or hand. The term appears in the names of arteries, nerves, and muscles, and in directional terminology such as radial vs ulnar.

Nervus radialis, the radial nerve, is a major nerve of the upper limb. It arises from the posterior cord of the brachial plexus (roots C5–T1), travels down the arm in the radial groove with the profunda brachii artery, and supplies the posterior compartment of the arm and forearm. In the forearm it divides near the lateral epicondyle into a superficial (sensory) branch and a deep motor branch that becomes the posterior interosseous nerve, which innervates most of the extensor muscles. Sensation from the dorsal, lateral hand and forearm is carried by its superficial branch.

Arteria radialis, or the radial artery, is a major forearm artery. It continues from the brachial artery at the elbow, runs along the lateral forearm between the brachioradialis and pronator teres, and enters the hand to contribute to the deep palmar arch. The radial pulse is commonly palpated at the wrist near the distal radius.

Several forearm muscles have -radialis in their names, indicating their relationship to the radius. Examples include flexor carpi radialis, extensor carpi radialis longus, and extensor carpi radialis brevis. These muscles act to flex or extend the wrist and to abduct or adduct the hand as appropriate.

Radialis is also used to describe radial direction or location in anatomical nomenclature, contrasted with ulnaris for the ulnar side.