Radius

Definition

The radius is one of the two long bones in the forearm, running parallel to the ulna, and plays a critical role in wrist and arm movement. It extends from the lateral side of the elbow to the thumb side of the wrist, enabling rotational motion of the forearm.

Related terms

Ulna: The bone that runs parallel to the radius on the medial side of the forearm, forming part of the elbow joint and extending to the smallest finger’s side of the hand.

Carpal bones: A group of eight small bones that make up the wrist joint, connecting the end of the radius (and ulna) to the metacarpal bones of the hand.

Supination: The rotational movement enabled by muscles acting on the radius that moves the forearm and hand into a position with palm facing up or forward.