Question
Which of the following muscles is not involved in overhead abduction of the arm?
| A. |
Serratus anterior
|
| B. |
Deltoid
|
| C. |
Trapezius
|
| D. |
Pectoralis major
|
Show Answer
|
Correct Answer � D
Explanation
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|
Pectoralis major: The pectoralis major muscle is primarily involved in adduction and internal rotation of the arm, not abduction. It works against the motion of abduction.
The primary muscles involved in the action of arm abduction include the supraspinatus, deltoid, trapezius, and serratus anterior.
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The supraspinatus is the primary muscle for the abduction of the arm to 15 degrees.
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The deltoid controls abduction from 15 to 90 degrees.
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The trapezius and serratus anterior coordinate with each other and the scapula to facilitate abduction of the arm upwards of 90 degrees.
