Understanding Back Pain: The Nervous System
The nervous system consists of your brain, spinal cord and the nerves which extend out to almost every organ and soft tissue in the body. There are nerves that carry information down from the brain called EFFERENT nerves and nerves which carry signals back up to the brain, called AFFERENT nerves. These nerves allow for you to have a thought such as, “I want to pick something up” and to be able to carry out the movements such as extending your arm to complete the task. Simultaneously, there are nerves which provide feedback to the brain to fine tune and coordinate the movements so that it is smooth and efficient. More simply, there are MOTOR NERVES (efferent nerves) which control movement and there are SENSORY NERVES (afferent nerves) which allow for sensation or feeling things. In back pain, because of the relationship of the nervous system with the spine, the neuromusculoskeletal system becomes dysfunctional and various problems result.
Pain is signaled to the brain via the afferent system so that your brain can quickly interpret the problem and carry out an action to solve it, such as moving your hand away from something hot. Pain is a signal to your consciousness that something is wrong and is an attempt to protect you from damaging a tissue even further. But in back pain, where does the pain actually come from? The answer is that it depends upon where in the nervous system the signal is coming from.
As discussed in parts 1 and 2, the spine is a series of moveable joints connected by muscles and ligaments which allow the spine to move in certain directions. But the function of the spine is also to protect and organize the spinal cord as it extends down from the brain. From the spinal cord extend smaller branches of nerves which exit to the right and left at each joint level. These are called NERVE ROOTS. For example, between the L4 and L5 vertebrae, the L5 nerve roots exit (one on the right and one on the left) and go out to the legs, branching off into smaller and smaller nerves the deeper they go into a tissue. Problems with a nerve root cause the classic “pinched nerve” type of pain. Rarely does a nerve actually become pinched; it is more commonly inflamed or irritated with the end result being pain or numbness and tingling traveling down an extremity. Sciatica is the most common example of this type of pain. However, a nerve can be irritated anywhere along its course for various reasons, so proper diagnosis is important. But what about common back pain that affects the everyday functions of life?
Most commonly patients experience back pain that comes and goes or hurts with certain positions/movements such as sitting or getting up and down from a chair. This is the type of pain that is not debilitating but affects daily functions. In this case, the pain arises not from the large nerve roots but from smaller nerves inside and around the joint, as well as those imbedded in the tiny muscles which attach one vertebra to the next. These nerves are very sensitive to changes in stretch, position and pressure and when irritated they send pain signals to the brain to prevent movement into a certain position that maybe be damaging to a nerve, a muscle or an intervertebral disc. These are the same nerves which are irritated with spinal joint dysfunction as discussed in issues 1 and 2. Furthermore, since most back pain is the end result of prolonged spinal joint dysfunction, we can finally see how these nerves, those which are imbedded inside the joint and its associated soft tissues, are responsible for back pain. So what does this all mean?
To simplify, the spinal joints, the soft tissues and the nervous system are designed to work in coordination with one another. Injuries and/or slow de-conditioning over time to any of these components result in joint dysfunction which ultimately causes pain as the result of irritation to nerves. This series serves to explain the basics regarding each of these components and how their overall structure and function contribute to spinal health.
Understanding your spine and how it works is the first step in maintaining spinal wellness and understanding why it is so important. Future segments will be dedicated to topics such as posture, scoliosis, childrens’ issues and providing you with functional tools in maintaining spinal health for you and your family.