Supinator

The supinator is a muscle within the deep compartment of the posterior forearm.

It forms the floor of the cubital fossa, and has two heads – which the deep branch of the radial nerve passes between.

• Attachments: Originates from the lateral epicondyle of the humerus and the posterior surface of the ulna. Inserts onto the posterior surface of the radius.

• Actions: Supination of the forearm.

• Innervation: Radial nerve (deep branch).
• Blood supply: Ulnar artery.

By TeachMeSeries Ltd (2025)

Fig 1
Muscles in the deep layer of the posterior forearm.