Specify the action of the muscle that is highlighted in the image.
Retraction of the scapula Abduction of the arm Flexion of the arm Depression of the scapula Extension of the arm Lateral rotation of the arm
The Correct Answer and Explanation is :
The muscle highlighted in the image is the trapezius, a large, triangular muscle located in the upper back and neck. The trapezius plays a crucial role in various movements of the scapula and the arm.
Actions of the Trapezius:
- Retraction of the Scapula: The middle fibers of the trapezius pull the scapulae medially toward the spine, a movement known as retraction. This action is essential for activities such as pulling the shoulders back.
- Elevation of the Scapula: The upper fibers of the trapezius elevate the scapulae, as seen when shrugging the shoulders.
- Depression of the Scapula: The lower fibers of the trapezius depress the scapulae, moving them downward.
- Upward Rotation of the Scapula: The upper and lower fibers work together to rotate the scapula upward, which is necessary for raising the arm above the head.
- Extension of the Neck: When the scapulae are fixed, the trapezius can extend the neck, as in tilting the head backward.
- Lateral Flexion and Rotation of the Neck: The upper fibers can laterally flex the neck to the same side and rotate it to the opposite side.
Understanding the actions of the trapezius is vital for comprehending shoulder and neck movements, as it contributes to the stability and mobility of the upper limb and neck.