The lateral epicondyle of the humerus is part of the origin of which muscle?

• A. Supinator
• B. Pronator Teres
• C. Brachioradialis
• D. Extensor Carpi Radialis

Answer: (A)

The main idea here is where forearm muscles attach near the elbow and how that affects their function. The lateral epicondyle of the humerus serves as a proximal anchor for muscles involved in forearm rotation and extension, and the Supinator has its origin at the lateral epicondyle (with additional attachment to the ulna). When the Supinator contracts, it wraps around the proximal radius and rotates the radius to turn the palm upward—forearm supination. That direct origin-on-pemetration connection is why this muscle is the correct choice. The other muscles start from different humeral landmarks or perform different actions: Pronator Teres starts medially and pronates the forearm; Brachioradialis originates on the lateral supracondylar ridge and mainly flexes the elbow; Extensor Carpi Radialis has a lateral-epicondyle-related origin but its primary action is wrist extension, not forearm rotation.