From the list below, which is the group of muscles that run parallel to each other on either side of the vertebral column in three pairs?

The correct answer is the group of muscles known as the erector spinae. The erector spinae is a group of muscles that run parallel to the vertebral column and consist of three primary muscle columns: iliocostalis, longissimus, and spinalis. These muscles are crucial for the extension and lateral flexion of the spine, contributing to maintaining an upright posture and supporting the spine during various movements.

The quadratus lumborum does play a role in spinal stability and lateral flexion but is not arranged in three distinct pairs running parallel to the vertebral column; rather, it is more of a quadrilateral-shaped muscle located in the lower back. The latissimus dorsi, while significant in upper body movements, is mainly focused on the shoulder and does not run alongside the vertebral column in the manner described. The serratus anterior is primarily involved in the movement of the scapula and does not have a parallel arrangement along the spine itself.

Thus, understanding the anatomy and function of these muscle groups highlights why the erector spinae is the accurate choice for this question.