Sit on seat in machine with feet apart . Position padded lever on side of head. Center body so neck is in line with lever axis. Grasp handles for support.
Move head down to side by laterally flexing neck. Return head to opposite side and repeat. Sit in machine backwards and continue with opposite side.
See all muscle used in Lateral Flexion:
Movement of the Thoracic / Lumbar Spine is typical in this movement. See animation of spinal lateral flexion.