Definition

By: Gregory R. Waryasz, MD

The supinator muscle of the musculoskeletal system is characterized by being a prime mover for slow, unopposed supination.

It is part of the forearm.  It consists of skeletal muscle fibers.

Its unique structural features include it forming the floor of the cubital fossa along with the brachialis.  It spirals medially and distrally from the continuous osseofibrous origin.  The muscle surrounds the proximal radius.

The origin is the lateral epicondyle of the humerus, radial collateral and anular ligaments, supinator fossa, and the crest of the ulna.

The insertion is the lateral posterior, and anterior surfaces of the proximal third of the radius.

The blood supply is from the radial recurrent artery and venous drainage is from the accompanying veins.

The innervation is from the deep branch of the radial nerve.

The supinator muscle as well as all other bones, muscles, and ligaments of the body are derived of mesodermal origin in the embryo.

The function of the supinator is to supinate the forearm.  The synergist is the biceps brachii.

Common diseases include radial tunnel syndrome.

Radial tunnel syndrome is a compressive neuropathy of the radial nerve. The radial nerve can be compressed by the supinator, the fibrous bands at the start of the radial tunnel, the blood vessels, or from the extensor carpi radialis brevis muscle tendon origin.  Symptoms include tenderness over the supinator muscle/lateral elbow. There can be numbness and tingling on the dorsum of the hand in the radial nerve distribution.  There is usually pain with resistance to supination and wrist extension.

Commonly used diagnostic procedures include clinical history, physical exam, EMG, and MRI.

It is usually treated with NSAIDs, physical therapy, and bracing for radial tunnel syndrome.  Surgery can be performed to decompress the nerve.

References

Lieberman J (ed), AAOS Comprehensive Orthopaedic Review, American Academy of Orthopaedic Surgeons, 2008.

Moore K, Dalley A (eds), Clinically Oriented Anatomy (5th edition), Lippincott Williams & Wilkins, Philadelphia, PA, 2006.

Wheeless’ Textbook of Orthopaedics: Supinator (http://www.wheelessonline.com/ortho/supinator)