Your Body’s Communication Network: Understanding the Anatomy of the Nervous System

The nervous system is quite literally aligned with every part and function of your body. Since it is so intertwined with every part of your body, it is a bit complicated to break down and cover it’s many different parts and functions. We will be covering the nervous system in a series of posts to allow space to cover the many jobs it does in the body.

First, let’s talk about the physical anatomy of the Nervous System. What most likely comes to mind are your brain, spinal cord and nerves – and you would be right! Your brain is the control center for your nervous system but in order to know what to control and to have anything to control it needs to be able to receive and send out messages. This is where you nerves come in. Your nerves are a part of an intricate and detailed network that branches out into your body. There also needs to be a way for these messages to get to and from your brain and nerves and that is your spinal column’s job.

We use several different terms to describe the nervous system. To explain the anatomy portions of the nervous system we have the Central Nervous System (CNS) and the Peripheral Nervous System (PNS). The Central Nervous System is made up of your brain and spinal cord. The Peripheral Nervous System is made up of the nerves that branch out from your spinal cord to each part of your body.

The Central Nervous System

The Central Nervous System includes your brain and spinal cord. Your brain and spinal cord are very delicate so the body has several protective mechanisms in place. You skeletal system protects them through your skull and the vertebrae of your spinal column. Next they are protected by the meninges which are three layers of membranes that cushion the brain and spinal cord. The meninges also contain the final protective layer, the cerebrospinal fluid to cushion the brain and spinal cord. The cerebrospinal fluid also brings nutrients to the brain and spinal cord and takes away the waste that is created.

The Peripheral Nervous System

The Peripheral Nervous System is anything outside of the brain and spinal cord, this means all of the nerves that travel from the spinal cord and out into the body are part of the peripheral nervous system. We name these nerves based on where they come out from the Central Nervous System. The nerves that branch out from the base of the skull are called the cranial nerves. There are 12 cranial nerves and they travel to the head, neck and face. The Spinal Nerves branch out from the spinal cord in the spinal column and are named according to the area that the branch out from. There are 8 Cervical Nerves that branch out into the head, neck, upper arms, and diaphragm. There are 12 Thoracic Nerves that branch out into your arms and hands, into your chest wall to help control your rib cage, lungs and diaphragm as well as branching into the muscles of your abdomen and back. There are 5 Lumbar Nerves and they branch out into the abdomen, hips, knees and ankles. There are 5 Sacral Nerves that branch through the pelvis and gluteal muscles and down through the legs to the ankle. There is 1 Coccygeal Nerve that branches into the area around the tailbone.

Remember how we said that in order to control the body well the brain needs to be able to send AND receive messages? Well each nerve that leaves the spinal column is actually a “pair” of nerves. One part of the nerve is considered a “motor nerve” because it carries directions from the brain to the part of the body that the nerve controls. The second part of the pair is considered a “sensory nerve” because it carries information from the part of the body the nerve controls back to the brain. This allows for communication to go both ways within your body and for your brain to have the best information to make decisions to keep you functioning and safe.

The Nerve Cell

The basic structural piece of the nervous system is the nerve cell or neuron. We are going to talk a little more in depth about what makes up the nerve. This will help us to understand how certain injuries and illnesses can hurt the nervous system in a later blog post.

The neurons are tiny structures that allow messages to pass back and forth between all parts of the nervous system. A nerve is a bundle of these neurons. The neuron bundle is protected by a layer of connective tissue. Within this tissue a non-neuron cell called a glia helps to keep the nervous system functioning and protected for example by creating the substance myelin that insulates the nerves and helps to move messages back and forth across the neurons.