Lateral epicondyle of humerus; radial collateral and anular ligaments; supinator fossa; crest of ulna

Lateral, posterior and anterior surfaces of proximal third of radius

Radial recurrent artery, posterior interosseous arteries

Deep branch of radial nerve (C₇, C₈)

Supinates forearm; rotates radius to turn palm anteriorly or superiorly (if elbow is flexed)