Multiple Choice
Which of the following muscles is NOT part of the rotator cuff?
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10. Muscles
Muscle Actions
Multiple Choice
Which muscle is the primary agonist responsible for extension of the elbow joint?
A
Brachialis
B
Biceps brachii
C
Triceps brachii
D
Pronator teres
Verified step by step guidance1
Step 1: Understand the term 'agonist' in muscle movement. The agonist is the primary muscle responsible for producing a specific movement at a joint.
Step 2: Identify the movement in question, which is extension of the elbow joint. Extension refers to straightening the elbow, increasing the angle between the forearm and upper arm.
Step 3: Recall the main muscles involved in elbow movement. The biceps brachii and brachialis primarily perform elbow flexion (bending the elbow), while the triceps brachii is responsible for elbow extension.
Step 4: Analyze the options given: Brachialis and biceps brachii are flexors, pronator teres is involved in forearm pronation, and triceps brachii is the only muscle that extends the elbow.
Step 5: Conclude that the triceps brachii is the primary agonist muscle responsible for extension of the elbow joint.
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