ACSM Personal Trainer Certification Practice Exam

Which joint movement is NOT typically associated with the pectoralis major?

1. Horizontal adduction

2. Abduction

3. Internal rotation

4. Extension

The correct answer is: Abduction

The correct answer is that abduction is not typically associated with the pectoralis major. The primary actions of the pectoralis major muscle include horizontal adduction, internal rotation, and extension of the humerus, particularly from a flexed position. When evaluating the functions of the pectoralis major, it's important to recognize how this muscle is anatomically positioned and how its fibers are oriented. The muscle originates from both the sternum and the clavicle and inserts into the humerus, which allows for powerful movements in front of the body. Horizontal adduction involves bringing the arm across the body, which is a key action of the pectoralis major. Internal rotation, on the other hand, reflects its role in rotating the arm toward the body. While the pectoralis major does assist with extension when the arm is elevated, it does not facilitate abduction, as that movement involves lifting the arm away from the body, which is primarily achieved through the deltoids and other muscles like the supraspinatus. Thus, understanding the anatomical function of the pectoralis major clarifies why abduction is not a primary movement associated with this muscle.