What is the action of the brachioradialis?

• A. Flex the elbow
• B. Extend the elbow
• C. Pronate the forearm
• D. Supinate the forearm

Answer: (A)

Brachioradialis primarily flexes the elbow. It travels from the lateral lower humerus to the radial styloid, crossing the elbow joint, so its main job is bending the elbow rather than extending it. It’s most effective when the forearm is in a neutral position (neither fully pronated nor fully supinated), which is why you’ll often feel it working during mid-pronation elbow flexion. It does not rotate the forearm itself—that’s the job of pronator or supinator muscles—so pronation and supination are not its actions.