Pronator quadratus

Definition

The pronator quadratus is a square-shaped muscle on the distal forearm that acts to pronate (rotate) the forearm and wrist, turning the palm downward. It lies between the ulna and radius bones of the forearm.

Related terms

Pronation:

The rotational movement of the forearm or foot that turns the palm or sole down or backwards, respectively.

Forearm: The part of the arm between the wrist and the elbow, consisting of two long bones (radius and ulna) surrounded by muscles.

Radius:

One of the two large bones in the forearm, located on the side of the thumb, which plays a key role in arm movement