The pronator quadratus is a muscle within the deep compartment of the anterior forearm. It is a square-shaped muscle which lies deep to the tendons of flexor pollicis longus and flexor digitorum profundus. Attachments: Originates from the anterior surface of the ulna and attaches to the anterior surface of the radius. Actions: Pronates the forearm. Innervation: Median nerve (anterior interosseous branch). Blood supply: Ulnar artery By TeachMeSeries Ltd (2025) Fig 1Deep flexor muscles of the anterior forearm. Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Print Article Rate This Article