ACSM Personal Trainer Certification Practice Exam 2025 – All-in-One Study Resource to Achieve Certification Success!

The trapezius muscle plays a multifaceted role in shoulder girdle movements, making "All of the above" the most accurate choice. It is a large, triangular muscle that extends from the back of the neck down to the middle of the back and out to the shoulder girdle.

The muscle is comprised of different fiber orientations that allow it to perform various functions effectively.

1. **Retraction**: The middle fibers of the trapezius are primarily responsible for pulling the scapulae (shoulder blades) together towards the spine, a movement known as retraction.

2. **Depression**: The lower fibers assist in depressing the scapula, moving it downward away from the shoulder.

3. **Elevation**: The upper fibers are involved in elevating the scapula, which raises it toward the ears.

Because the trapezius muscle is involved in all three of these movements, it highlights its significant role in stabilizing and mobilizing the shoulder girdle, enabling a greater range of motion and effective arm movement. This comprehensive functionality demonstrates how integral the trapezius is to shoulder girdle dynamics, affirming that "All of the above" is the correct response.