Which of the following is not considered a spinal muscle?

The infraspinatus is not considered a spinal muscle because it is primarily located in the shoulder region and is part of the rotator cuff group of muscles. Its main function is to stabilize the shoulder and facilitate arm movements, rather than providing support or movement to the spinal column.

In contrast, the rhomboid muscles, located between the shoulder blades, function to retract the scapulae and provide stability to the upper back, contributing to the overall support of the spine. The erector spinae is a group of muscles specifically designed to extend and laterally flex the vertebral column, playing a crucial role in maintaining posture and spinal alignment. The latissimus dorsi, while also a large muscle involved in shoulder movement, has attachments that extend to the lower spine and pelvis, thus contributing to movements that affect the lower back and spine as well.

In this context, recognizing the functions and locations of these muscles helps clarify why the infraspinatus does not fall under the category of spinal muscles.