객관식
Which facial muscle is primarily responsible for raising the eyebrows?
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10. Muscles
Muscle Actions
객관식
Which muscle is the prime mover for abduction of the arm at the shoulder (glenohumeral) joint?
A
Deltoid (middle fibers)
B
Pectoralis major
C
Teres major
D
Latissimus dorsi
검증된 단계별 안내1
Step 1: Understand the term 'prime mover' (agonist) — it refers to the muscle primarily responsible for producing a specific movement at a joint.
Step 2: Identify the movement in question, which is abduction of the arm at the shoulder (glenohumeral) joint. Abduction means moving the arm away from the midline of the body.
Step 3: Recall the main muscles involved in shoulder movements: the deltoid, pectoralis major, teres major, and latissimus dorsi, and understand their primary actions.
Step 4: Analyze each muscle's function: the deltoid (especially its middle fibers) is known for abducting the arm; pectoralis major primarily adducts and medially rotates the arm; teres major and latissimus dorsi mainly adduct and medially rotate the arm.
Step 5: Conclude that the deltoid muscle, specifically its middle fibers, is the prime mover for abduction of the arm at the shoulder joint.
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