Elevating 'The Gravity' of Gravity

"The nervous system controls all other systems and relates the individual to his or her environment."
Gray's Anatomy, 29th American Edition, Page 4

For Pettibon practitioners, Dr. Henry Gray's fact is interpreted as:

  • Humans develop, act and react in time and need to their environment under the direction and control of the nervous system.

For Pettibon practitioners, humans' functional spinal environment is gravity. And gravity is an absolute environment to which the upright spine and posture must develop and relate to.

The role that gravity plays in how the spine gets displaced and subluxated is fundamental to Pettibon chiropractic principles. As Burl explains, "The nervous system always wants us to hold our heads upright. And the nervous system will do this at the expense of subluxlating the lower spine."

The Ten Key Principles of The Pettibon System

  1. The skull is a vertebra. It's the only vertebra that is assured of its position in three- dimensional space. The nervous system's five righting reflexes continually send it positional information about the skull. The nervous system, acting on this reflex information, then works with the brain to produce an innate organizing energy that contracts and relaxes muscles of the lower spine as needed to hold the head upright. The inference of the nervous system's attention to the skull's position is that the nervous system considers the skull to be the spine's most important vertebra.
  2. The normal global spine is divided by the opposing spinal curves of the human spine into six functional, crank-like lever arm units upon which spinal muscles act. The six spinal units-made up of vertebrae working together as a part of the lever arm system-rather than each vertebra, is considered a separate functional or motion unit. After the skull, the global spine's position is the most important. And the global spine's position relative to gravity must be corrected first, if it's displaced, before additional corrections can take place.
  3. A spinal unit's position and function are second in importance—subservient to the global spine. A spinal unit is either in a normal position, a compensated subluxated position, a non-compensated subluxated position, or an uncompensated subluxated position. These unit positions are logical and explain expected spinal functions or non-function.
  4. Individual spinal vertebra does not subluxate independent of its unit unless the ligaments that hold the vertebra together are torn. Individual spinal vertebra is last in importance. If ligaments aren't torn, the vertebra will be corrected by global or spinal unit corrections.
  5. Muscles control the global spine, spinal units, and posture. Muscles' actions are directed by the nervous system and the innate organizing energy it creates. With the sensory input it receives from the five righting reflexes, the nervous system and the innate organizing energy organizes and re-organizes the lower spine and posture into displaced positions or aligned positions in order to keep the skull upright.
  6. Gravity is an absolute environment to which the upright spine and posture of humans must develop and relate.
  7. Since gravity is an absolute, there has to be an absolute optimum position for the upright spine and posture. The spine functions best when it's in its optimum position relative to gravity.
  8. A less than optimum spine and posture position (form), relative to gravity, results in the loss of the spine's function and the individual's ability to function optimally.
  9. The nervous system has five righting reflexes that continually send it skull and spine positional information. The five righting reflexes and their functions are:
    • Labyrinthine Reflex (inner ear). Its function is to maintain the head's orientation in space (medulla).
    • Optic Reflex (ocular). Its function is to keep the head in proper orientation to its gravitational environment (occipital cortex).
    • Neck Righting Reflex (joints of the neck). Its function is to orient the body in space (midbrain).
    • Body Righting Reflex # 1 (from the body's surface receptors). Its function is to orient the body in space (midbrain).
    • Body Righting Reflex #2. Its function is to keep the head oriented to the body (midbrain).


      Arthur C. Guyton, M.D., Textbook of Medical Physiology,
      Philadelphia: WB Saunders Company, 2000

  10. Collectively, the righting reflexes and the nervous system's innate organizing energy control all aspects of the muscular-skeletal system so that the lower spine is organized and/or reorganized in time and in need in order to hold the head upright with respect to gravity (front-to-back and side-to-side).