Muscle · Elbow

Supinator

Musculus supinator

A flat muscle that wraps around the top of the radius and rolls the palm face-up. It is the supinator you use when the elbow is straight or the effort is light; add resistance or bend the elbow and the biceps takes over as the powerful one. Clinically its most important feature is a relationship rather than an action: the deep motor branch of the radial nerve tunnels straight through it, so a swollen or overworked supinator is a classic site of nerve compression that can be mistaken for stubborn tennis elbow.