The supinator is a muscle within the deep compartment of the posterior forearm. It forms the floor of the cubital fossa, and has two heads – which the deep branch of the radial nerve passes between. Attachments: Originates from the lateral epicondyle of the humerus and the posterior surface of the ulna. Inserts onto the posterior surface of the radius. Actions: Supination of the forearm. Innervation: Radial nerve (deep branch). Blood supply: Ulnar artery. By TeachMeSeries Ltd (2025) Fig 1Muscles in the deep layer of the posterior 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