The supinator is one of the muscles of the deep layer of the posterior compartment of the forearm. The supinator muscle wraps itself around the proximal radius enabling its function in supinating the forearm.

The posterior compartment of the forearm consists of a superficial layer (7 muscles) and a deep layer (5 muscles).

All the muscles of the posterior compartment are innervated by the radial nerve.

The muscles of the deep layer include:

Origin

2 heads – superficial and deep

  • Superficial (humeral) head: lateral epicondyle of humerus, annular ligament, radial collateral ligament
  • Deep (ulna) head: supinator crest and posterolateral surface of ulna
Insertion
  • Lateral surface of proximal third of the radius – superior to the anterior oblique line and the insertion of the pronator teres
Innervation
  • Deep branch of radial nerve
Blood Supply
  • Superficial part – radial recurrent artery
  • Deep part – posterior interosseus and interosseus recurrent artery
Antagonist

Pronator teres and pronator quadratus

Action
  • Supination of the forearm: rotates the radius to bring the palm facing anteriorly