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The Central & Peripheral Nervous System

The nervous system is a large and complex body system. It is responsible for regulating all of our conscious and unconscious movements, memories, and more. It is one system; however, in order for scientists and wellness experts to discuss it clearly, the nervous system is divided into several subsystems according to their respective functions. A critical piece of the puzzle is understanding the two main structural components of the nervous system and how they relate to each other.


The nervous system is divided into two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS).

The CNS is made up of the brain and spinal cord. The brain is an organ that weighs about three pounds and lives in the skull. It is, arguably, the most complex organ in the entire body, and is often referred to as “the seat of consciousness.” There is a lot about the brain that we still don’t understand, although through scientific and medical advances, we’ve learned more about the brain in the past 10 years of research than ever before. We do know that the brain is made up of two types of tissue:; about 40% of the brain is grey matter, and the other 60% is white matter.

The spinal cord starts at the brain stem and extends down the back through the center of the spine. It ends in the lumbar region of the spine (low back). So, the CNS covers the area starting at the brain and running all the way down the spine—quite a large region of the body.

The PNS is made up of nerves that connect the CNS to the limbs and organs. There are 12 cranial nerves (meaning they start at the head) and about 31 pairs about spinal nerves (nerves that originate from various parts of the spine). Unlike the CNS, the nerves of the PNS are not protected by bones, so they are more susceptible to damage. The PNS moves from the CNS out to the rest of the entire body, making the nervous system quite very comprehensive.


The PNS carries signals to and from the CNS. It gathers information from the internal and external environments of the body and sends that information to the CNS for processing. The grey matter in the brain is primarily responsible for this processing, while the white matter helps send information to different areas of grey matter. The brain makes a decision on how to respond to the information it is given, and sends out signals to the rest of the body by way of the PNS.

The spinal cord helps to connect the brain to the PNS, and is also responsible for carrying out reflexes. If you touch a hot stove, a signal is sent via the PNS to the spinal cord. The spinal cord responds with a reflex to pull your hand away from the stove quickly. If the signal went all the way to your brain, by the time your body responded, there may might already be tremendous damage to your hand. Therefore, the spinal cord sends the signal for the reflexive response so you can pull your hand away from the stove before your brain senses the danger (and pain).

Why Take Care of the CNS and PNS?

Take a moment and imagine a classroom. First, picture the classroom with no teacher. There are several students, all picking up interesting bits of information about their environment, but with no teacher to help guide them. Now picture the same classroom with a teacher but no students. The teacher has great ideas to share with the class, but without any students, she can’t get very far. For an effective classroom setting, you need both the students, hungry for knowledge and sharing all sorts of insights; and a teacher, who can help guide and focus the students toward productive activities. The nervous system is much like the classroom. Both the PNS (students) and the CNS (teacher) are needed for your body to function properly.

Because the nervous system is so large and spans the entire body, if you experience any kind of pain, injury, or condition anywhere in the body, it likely will affect your nervous system. Unfortunately, nerve cells cannot regenerate, so if a nerve gets damaged or destroyed, that’s it. If someone experiences a concussion, which is trauma to the head, several brain cells quite literally die. Those brain cells will never regenerate, so the capacity for the CNS to receive and process information is compromised.

Similarly, if you develop tendinitis in your shoulder, the inflammation (though it comes with the best intentions of healing the injury) increases the pressure inside the joint. All joints are designed to have a certain amount of space so all the bones, tendons, nerves, and muscles have room to function properly. Since the PNS has nerves that pass through all your joints, if there is too much compression in the joint, a nerve may become compressed or impinged. Compression of a nerve is very painful and can lead to irreversible damage. Say the swelling is persistent, but doesn’t compress the nerve. You’re good, right? Maybe not. Swelling triggers a buildup of connective tissue which becomes hard (or dehydrated) to protect the joint from further injury. This connective tissue is sometimes referred to as scar tissue. Scar tissue tends to be very strong and inflexible. Scar tissue that surrounds a nerve can lead to a condition called nerve entrapment. When a nerve is entrapped, the scar tissue and adhesions prevent signals from being transferred through the nerve. Both nerve impingement and nerve entrapment create blockages in the communication pathway between the body and brain, which decreases the nervous system’s efficiency and effectiveness.

When in perfect alignment, the body is the healthiest, most efficient version of itself. All the joints have the proper amount of space, and the muscles are proportionately strong and stretched. Unfortunately, no one has perfect alignment. Years spent repeatedly taking postures where the weight distribution is not equal on the left and right sides (and front and back) take their toll on our bodies, leading to all sorts of injuries and conditions which can inevitably cause damage to the nervous system. By practicing better alignment in your everyday life, you decrease your risk of developing injuries (like tendinitis) and set yourself up for a happy, healthy nervous system.

Common Ailments

Common ailments that affect the CNS include encephalitis, ADHD, autism, Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and certain forms of cancer. Common ailments that affect the PNS include autonomic neuropathy, burning feet, pinched nerves, dysautonomia, and hereditary spastic paraplegia.

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