Which action is most characteristic of the brachioradialis muscle at the elbow joint?

• A. Pronation of the forearm at the radioulnar joints
• B. Extension of the forearm at the elbow
• C. Flexion of the forearm at the elbow, especially when the forearm is in a neutral (thumb-up) position
• D. Primary supination of the forearm at the radioulnar joints

Answer: (C)

Verified step by step guidance

1. Step 1: Identify the anatomical location and attachments of the brachioradialis muscle. It originates from the lateral supracondylar ridge of the humerus and inserts near the styloid process of the radius.
2. Step 2: Understand the primary function of the brachioradialis muscle. It acts mainly at the elbow joint and influences forearm movement.
3. Step 3: Recall that the brachioradialis is unique because it flexes the forearm at the elbow, especially when the forearm is in a neutral position (thumb pointing upward), unlike other muscles that flex with the forearm supinated or pronated.
4. Step 4: Differentiate the brachioradialis action from other movements such as pronation, supination, and extension at the elbow. It does not primarily cause these actions.
5. Step 5: Conclude that the most characteristic action of the brachioradialis at the elbow joint is flexion of the forearm, particularly when the forearm is in a neutral position.