Multiple Choice
Which statement best describes the action of the zygomaticus major muscle?
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10. Muscles
Muscle Actions
Multiple Choice
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
Verified step by step guidance1
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.
Step 2: Understand the primary function of the brachioradialis muscle. It acts mainly at the elbow joint and influences forearm movement.
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.
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.
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.
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