Supinator

The Supinator muscle assists Biceps Brachii in supinating the hand, that is turning it over so that the palm faces up. To isolate the supinator muscle, supinate the hand whilst extending the elbow as this takes out the Biceps muscle.

Origin

  • Lateral supracondylar ridge of the humerus. 
  • Posterior part of the ulna. 

Insertion

  • Outer surface of the upper third of the radius. 

Actions

  •  Supination. 

Innervation

  • Posterior interosseous branch of the radial nerve. 

Daily uses

  • Turning a screwdriver. 

Example strengthening exercises

Related muscles