Supinator

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The Supinator is in the Deep Layer of the Posterior Compartment of the forearm.

The Supinator has two layers: Superficial Layer and Deep Layer.

ATTACHMENTS:

• Lateral epicondyle of the humerus and the proximal ulna to the proximal radius.
  • The proximal ulnar attachment is onto the supinator crest of the ulna.
  • The distal attachment is onto the proximal 1/3 of the posterior, lateral, and anterior radius.

ACTIONS:

• Supinates the forearm at the radioulnar joints.

NOTES:

1. The supinator and pronator teres muscles attach at nearly identical locations on the radius, but approach the radius from different directions, hence the antagonistic joint actions of supination versus pronation.
2. The posterior interosseus nerve (a branch of the radial nerve) runs between the two layers of the supinator and can become compressed there.