Pronator quadratus muscle

Pronator Quadratus Muscle

The Pronator Quadratus is a square-shaped muscle on the distal forearm that plays a crucial role in the pronation of the forearm. It is one of the primary muscles involved in turning the forearm so that the palm faces downwards. This muscle is located on the anterior side of the forearm, just above the wrist.

Anatomy

The Pronator Quadratus originates from the distal quarter of the anterior ulna and inserts into the distal quarter of the anterior radius. It is the deepest muscle in the distal forearm, lying just above the interosseous membrane that separates the ulna and radius bones. The muscle fibers run horizontally from the ulna to the radius.

Blood Supply and Innervation

The Pronator Quadratus receives its blood supply from the Anterior interosseous artery, a branch of the Ulnar artery. Its innervation is provided by the Anterior interosseous nerve, which is a branch of the Median nerve.

Function

The primary function of the Pronator Quadratus is to pronate the forearm. Pronation is the movement that turns the hand so that the palm faces posteriorly (downwards when the arm is outstretched). This muscle works in conjunction with the Pronator Teres muscle to achieve full pronation of the forearm. It also plays a minor role in stabilizing the distal radioulnar joint during forearm movements.

Clinical Significance

Injury to the Pronator Quadratus can result from fractures of the distal radius or ulna, and can lead to difficulty in pronating the forearm. Its location and function also make it a landmark in surgical procedures involving the forearm and wrist.

Rehabilitation

Rehabilitation exercises targeting the Pronator Quadratus include pronation and supination movements against resistance. Strengthening this muscle can help in the recovery from injuries and improve forearm function.

See Also

• Forearm muscles
• Pronation and Supination
• Distal radioulnar joint
• Median nerve