"When the head moves in any of the three planes it will create spinal joint motion in a “top-down” sequence. The driving force is moving down into the spine. In contrast, when the pelvis moves in response to the legs, that pelvis movement will create lumbar spinal joint motion from the “bottom-up”. The driving force is coming up into the spine. When the shoulders rotate in the transverse plane, motion will be driven “top-down” into the thoracic and lumbar spine. At the same time the cervical spine will experience “bottom-up” motion in the opposite direction. Simultaneously the driving force is down into the thoracic and lumbar while up into the cervical."