The term chiropractic is practically synonymous with the term adjustment. Many people swear by that relief providing crack or pop delivered by their chiropractor. But what is happening here? Why does it feel so good? This week’s post will provide a brief explanation of what an adjustment is and a couple of things that take place physiologically.
First off, an adjustment, also referred to as a manipulation takes place when a force is applied, mainly to a joint, in order to deliver stimulation to that area or beyond. Although not always necessary for an adjustment to occur, the crack or cracking you hear is known as a cavitation.
Many of our joints are lined with synovial fluid that keeps them lubricated and assists in smooth movements. Due to the contour of the bones and cartilage that make up each joint, a bubble lined with synovial fluid and filled with gas forms. When a joint is taken slightly beyond its end range that bubble has the potential to pop and thus you have your satisfying crack. Eventually gas and pressure refills the joint and another synovial bubble is re-established. This is not instantaneous and the reason why immediate successive cavitations are rare.
So let’s now take a look at some of the physiological explanations for the potential benefits the adjustment can provide. If you’ve received an adjustment before, you most likely have experienced a release of tight musculature. Whether it be a stiff neck, stiff back, or headache, introducing a stimuli that causes a spazzing muscle to relax can seem life saving.
The reason this occurs is due the fact that most of our skeletal muscles attach either directly or indirectly to a joint. During an adjustment, when a joint is taken to and beyond that end range that I mentioned, the muscles that attach to that to that joint (directly or indirectly) are stretched.
This stretching stimulates receptors called GTOs (Golgi Tendon Organs) that are located in the tendons of the muscle. The GTOs send a signal back to the spinal cord by way of your peripheral nerves, that sends a signal back out to that same muscle that was stretched, inhibiting or relaxing that muscle. So now those tight trapezius muscles causing a stiff neck, or those over-contracted sub-occipital muscles contributing to a tension headache are “turned off” due to the fast stretch provided by the adjustment, and thus relief is experienced.
Another powerful and extremely beneficial therapeutic mechanism served up by an adjustment is that of an analgesic or pain killer. We have certain nerves that pick up the sensation of nociception or pain. This can be for a variety of reasons, but very often is due to physical trauma or inflammation. (The chemicals released by your body during inflammation actually stimulate these nociceptive nerves.)
The nerve fibers that transmit this nociceptive signal, synapse or connect in the spinal cord where the signal is sent north to the brain, where it is perceived as pain. Fortunately for us, these nociceptive nerve fibers are small and slow and can be over-ridden by their larger, faster counterparts. This is a phenomenon called closing the physiological pain gate. This gate can be closed in your spinal cord due to collateral connections and shared pathways of our nerves. Due to the fibers that transmit non-painful stimuli, including touch, being bigger and faster, they have the ability to cut off or close the gate on the transmission of nociception and thus the perception of pain.
You may have experienced this fascinating phenomenon before by shaking or rubbing your hand after banging it against something. By shaking or rubbing, you stimulated these bigger, faster fibers and thus closed the physiological pain gate in your spinal cord. You are provided temporary relief because the signal that would normally stimulate your brain to perceive pain in brain has been blocked in the spinal cord.
The way in which an adjustment has a strong influence on the pain gate is due to the fact that our joints are heavily populated with sensory receptors called mechanoreceptors. More so than any other region of our body as a matter of fact, with the joints of the spine being the most densely populated. These mechanoreceptors transmit their signal by way of fibers bigger and faster than those pain producing fibers. When stimulated by an adjustment, especially one where the aforementioned joint bubble pops, you are bombarded by sensory input and provided with arguably the most powerful way of manually closing the pain gate.
(It should be noted that we are always looking beyond the pain and into what is causing that pain. However, while investigating and addressing the underlying cause, the adjustment is capable of providing some much desired relief for the patient.)
Perhaps most importantly though is what the adjustment can do for us centrally. When I say centrally, I am referring to our master control center, the brain. As covered in previous posts on functional neurology, our brain is made up of two separate but interconnected hemispheres. For various reasons, these hemispheres can become imbalanced, leaving one side functioning at a lower level. This can manifest itself in a countless numbers of ways from constipation or sexual dysfunction, to an over or under active immune system.
Due to in depth study and subsequent mapping of our internal wiring, decreased function of our left or right cerebral hemisphere (aka hemisphericity) can be ascertained through observation of various forms of outward signs and symptoms. The side of the body that which these outward expressions take place offers clues to a possible deficit on the corresponding side of the brain. Things such as posture, accuracy and quickness of movements, pupillary response to light, etc. can all be measured and used to form a diagnosis and subsequent treatment plan.
An adjustment is one of the strongest tools in addressing a potential hemisphericity for a variety of reasons. One is due to the extremely high number of mechanoreceptors located within a joint, leading to an extremely powerful stimuli delivered to the spinal cord and up to the brain.
The second reason the adjustment can be such a powerful tool is due to the knowledge of our internal wiring. When I say internal wiring I am speaking specifically of the pathways that the sensory input travels from joint to our brain. We know that sensory input or an adjustment from one side of the body will ultimately cross over and affect the opposite side of our brain.
What this all means is that if a right sided deficit is discovered in the brain, an adjustment to the left side of the body can be delivered knowing that it should reach and stimulate the right side of the brain. There are many ways that this influence on central function can be confirmed such as measuring the size of our blind spots, but these are other topics for another post. The point is that the adjustment has been shown through research to have a direct effect on the level of functioning of the brain. And that my friends is some powerful stuff.