The supinator (or supinator muscle, latin: musculus supinator) is a small muscle of the forearm that belongs to the posterior muscle group, lying in the second or deep layer.
The supinator originates from the lateral epicondyle of the humerus, the supinator fossa and the crest of the ulna.
The supinator inserts onto the lateral, posterior and anterior surfaces of the proximal third of radius.
The main function of the supinator is supination of the forearm.
The supinator is innervated by the radial nerve.