Supinator Muscle, Posterior View

Description

Posterior forearm anatomy centers on the supinator wrapping around the proximal radius, spanning from the lateral epicondyle region and supinator crest of the ulna toward the lateral and anterior surfaces of the radial shaft. Superficial to it lie the extensor muscle mass, including extensor digitorum and extensor carpi ulnaris more medially, and extensor carpi radialis longus and brevis more laterally, with brachioradialis forming the lateral border toward the distal humerus. Proximally, the anconeus sits posterolateral to the elbow, while distally the extensor tendons course toward the dorsum of the wrist. Deep relations are the point: the posterior interosseous nerve (deep branch of the radial nerve) passes through the supinator at the arcade of Frohse near the radial neck. Tight quarters. Compression of the posterior interosseous nerve within the supinator produces posterior interosseous nerve syndrome, classically presenting with finger and thumb extension weakness without cutaneous sensory loss, a pattern that helps separate it from more proximal radial neuropathy. This posterior perspective also maps cleanly onto surgical approaches to the proximal radius and radial head, where the supinator must be respected to protect the nerve and preserve supination strength. Anatomy at the radial neck matters. Educators will find this view practical for upper limb gross anatomy labs when teaching the deep extensor compartment and the transition from superficial extensors to the supinator plane. It also supports orthopedic and hand surgery texts discussing radial tunnel decompression, radial head fracture exposure, and postoperative weakness patterns after proximal forearm dissection. Anatomical accuracy verified by SciePro's Medical Advisory Board.