Pronator quadratus muscle

The pronator quadratus muscle is a muscle in the forearm near the wrist that serves to pronate the hand. It also helps to keep the distal radius and ulna together.

Origin
The pronator quadratus originates from the ulna, on the lower quarter of anterior medial shaft.

Insertion
The pronator quadratus inserts on the radius, at the lower quarter of anterior lateral shaft. Some fibers also attach at interosseous membrane between the radius and ulna.

Innervation
The pronator quadratus is innervated by the anterior interosseous nerve (C8).