Spinal Anatomy Exam III Practice

Intrinsic back muscles are the deep group that originate on the spine and act primarily on the vertebral column to stabilize and move the spine. Rotatores fit this description perfectly: they are tiny, short muscles of the transversospinales that extend from a transverse process to the spinous process of a nearby vertebra above. Their main roles are stabilizing the spinal segments and assisting in rotation and slight extension of the spine. This places them squarely among the intrinsic back muscles. The other options work on the shoulder girdle or rib cage rather than the spine itself, so they’re considered extrinsic back muscles. Latissimus dorsi, for example, originates from the pelvis and lower spine and attaches to the humerus to move the arm. Levator scapulae and serratus posterior inferior mainly act on the scapula or ribs rather than the vertebral column.