The Science of Chiropractic
Yes chiropractic is scientific! Here I will go through some of the basic neurology and neurophysiology that explains the importance of the spine in neurological movement patterns and the effect it has on the vesibular nuclei. It is a little bit heavy in places, however I will reference it all so that you can explore it in your own time. If you are more interested in what the science means to you as an individual, then please go to the banner headed Real Life Cases, to see how chiropractic could benefit you and your family.
So, very basic neurology. When your body interacts with the environment there are various sense organs that turn a variety of senses into a stream of electrical impulses that travel along nerves to tell your brain about the environment. Examples of the types of senses include the eyes which turn light into a series to electrical impulses in the optic nerve. Free nerve endings which interpret pain and convert that into nerve impulses. Also we are aware of temperature, pressure, body position, various tastes amongst others. In each example a specific and specialised nerve ending senses the environment and transmits impulses to the brain along its nerve pathway to tell the brain what environment we are in. eg windy, cold, warm, sweet, light, uneven etc etc.
All of this allows the brain to build an internal representation of the environment so that it may respond appropriately, by sending messages back out along nerves to end organs to (for example) move muscles, raise heart rate, constrict blood vessels, secrete digestive enzymes etc etc. Now not all of these processes involve higher brain functions such as cortical thought, and some rely on chemical processes, such as the chemical cholecystokinin (CCK) one of the many chemicals involved in telling the brain our stomach is full. Many neurological processes rely on reflex loops at both the spinal cord level as well as the brain stem and cerebellum to coordinate and adapt accordingly, such as balance, pain reflexes, deep tendon reflexes, but each of these can be overridden by the brain, such as dampening the startle reflex if your holding your new IPad.
If we focus on movement and balance then there is one main centre for orientation, the vestibular nuclei in the brain stem which relies on information from the body (proprioception or body position sense), from the eyes (to gauge the horizontal) and the inner ears (otoliths and semi-circular canals, for acceleration and rotation). Body position sense is formed from end organs such as golgi tendon organs and muscle spindle cells. When all three combine accurately and are balanced from one side to the other, the brain knows when we are balanced, upright and stationary.
So far so good, now what would happen if there was a disturbance to this system? What if, for example, a spinal joint were to become restricted? We could note that the nerve impulses regarding movement would not be coming from that joint, or its surrounding muscles and tendons, and gradually the nerve would weaken (nerves have their own metabolism and so the less a nerve is used the weaker it gets). This could lead to an imbalance across the vestibular nuclei from one side to the other, which would require a compensation.
Now the compensation could come gradually, such as in the form of a postural change (eg a head tilt, check the bottom of your ears in the mirror, are they level just after you open your eyes?), or more immediately in the form of a muscle spasm, but either way a lack of neurological information from one (or many) joints could be the culprit. So the next time you look in the mirror and see that one side of the pelvis is slightly higher than the other, or indeed one shoulder sits lower higher, then it could be a neurological imbalance driving that adaption process.
By restoring motion to the individual spinal segments a more accurate depiction of the environment is brought about in the brain stem and cerebellum allowing for more accurate responses in the neuromusculoskeletal system. This is why muscle spasm settles down, or posture is improves, or sports performance is enhanced.
So this is an extremely brief introduction and simplification of the extremely complex world of the neurology of chiropractic which I hope gives just a sense of what is involved. The science and the research are robust, and continue to be refined.
If you would like more information please contact the clinic and Dr Blackwood will be more than happy to meet and talk this through.
Chiropractic Development International
Kandel Schwartz and Jessell – Principles of Neural Science
H Haavik-Taylor, B Murphy – Cervical spine manipulation alters sensorimotor integration: a somatosensory evoked potential study – Clinical neurophysiology, (2007)