Your peripheral nervous system (PNS) is one of two main parts of your body’s nervous system. Your PNS feeds information into your brain from most of your senses. It carries signals that allow you to move your muscles. Your PNS also delivers signals that your brain uses to control vital, unconscious processes like your heartbeat and breathing.
Your peripheral nervous system (PNS) is that part of your nervous system that lies outside your brain and spinal cord. It plays key role in both sending information from different areas of your body back to your brain, as well as carrying out commands from your brain to various parts of your body.
Some of those signals, like the ones to your heart and gut, are automatic. Others, like the ones that control movement, are under your control.
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Your nervous system consists of two main parts: your central nervous system and your peripheral nervous system. Your central nervous system includes two organs, your brain and spinal cord.
Your peripheral nervous system is everything else and includes nerves that travel from your spinal cord and brain to supply your face and the rest of your body. The term “peripheral” is from the Greek word that means around or outside the center.
Your peripheral nervous system has two main subsystems: autonomic and somatic.
Those two subsystems are how your peripheral nervous system does its three main jobs:
Your brain is like a powerful supercomputer. However, it knows nothing about the world outside your body without outside input. That’s why your peripheral nervous system is so important. A computer needs peripheral devices like a camera, microphone or keyboard to give it information from outside itself, and your brain is the same.
Your peripheral nervous system is how your brain gets information about the outside world. Most of your peripheral nervous system travel to the rest of your body by exiting or entering your spinal cord. Your cranial nerves are unlike other peripheral nerves in that these very special nerves connect directly to your brain. These nerves carry signals from your nose, ears and mouth, as well as many other organs. Your cranial nerves also give you a sense of touch in the skin of your face, head and neck.
Other peripheral nerves intertwine throughout every part of your body. They stretch out everywhere, including to the tips of your fingers and toes. The sensory nerves in your hands and feet are also part of your brain’s ability to get information from the outside world. The motor nerves allow you to move various parts of your body.
Your peripheral nerves that branch outward throughout your body deliver command signals from your brain to your muscles. That allows you to move around and do all kinds of tasks, ranging from simple ones, like scratching your nose, to complicated ones, like juggling.
Your autonomic nervous system functions without you thinking about it. Part of your brain is always working, managing processes that keep you alive. Your brain needs your peripheral nervous system to control those functions. Examples of these processes include your heart rate, breathing, blood pressure and your gut’s digestion of food.
Your nerves consist of bundles of nerve cells, which have long, arm-like extensions called axons. The nerve cells and their axons twist and intertwine together to form nerve fibers. This is similar to how multiple strands of spun cloth fibers twist together to form sewing thread. Some of the nerves in that bundle carry information into your brain, while others carry information out of your brain.
Your autonomic nervous system, which is a part of your peripheral nervous system, helps your brain control all of the vital organs in your body. That also helps your brain care for itself. An example of this is your brain controlling your heartbeat, which ensures your heart pumps blood to your body and brain. Without that blood flow, your brain would die in minutes.
Your peripheral nervous system also relays nerve signals from those organs to your brain. Examples include feeling warmth inside of your stomach when you drink a hot beverage or feeling full after a meal.
Your peripheral nervous system extends everywhere in your body that isn’t your spinal cord or brain. It includes:
The above nerves all branch out and become smaller nerves that spread throughout your body. They eventually end at places like the tips of your fingers and toes or just underneath the surface of your skin.
One way to imagine the nervous system is like an upside-down tree, with your brain as the root of the tree and your spinal cord as the tree’s trunk. Your peripheral nervous system spreads out through the rest of your body like limbs, branches and twigs of the tree.
Your peripheral nervous system consists of various types of nerve cells and structures. Peripheral nerves and cranial nerves have command centers that are neurons as well as highways that send information called axons and dendrites. The cell types are as follows, with more about them listed below:
Neurons are the cells that send and relay signals through your nervous system, using both electrical and chemical signals. Each neuron consists of:
Neuron connections are incredibly complex, and the dendrites on a single neuron may connect to thousands of other synapses. Some neurons are longer or shorter, depending on their location in your body and what they do.
Glial (pronounced glee-uhl) cells have many different purposes, helping develop and maintain neurons when you’re young and managing how the neurons work throughout your entire life. They also protect your nervous system from infections, control the chemical balance in your nervous system and create the myelin coating on the neurons’ axons. Your nervous system has 10 times more glial cells than neurons.
There are many conditions and causes of peripheral neuropathy, which means disease or damage of your peripheral nervous system. Some of the most common examples include:
Your peripheral nerves may also show effects of conditions that affect any part of your central nervous system. While these don’t directly affect your peripheral nervous system, they can still disrupt how it works.
The symptoms of peripheral nervous system problems depend on the types of nerves affected.
Damage to motor nerves affects your muscles by causing:
Damage to sensory nerves causes the following symptoms:
Damage to your autonomic nerves can affect the following organs and systems:
Many tests can help diagnose conditions that affect your peripheral nervous system. The most common starting point is a neurological exam, where your healthcare provider has you use different parts of your body, especially arms, hands, legs and feet, in certain ways.
Some of the most common tests include:
The treatments for peripheral nervous system problems are as varied as the problems themselves. In many cases, treating the underlying cause of peripheral nervous system issues can relieve the effects on that system. It’s also common that treatments for a condition (or similar conditions) won’t work for other kinds of problems.
Potential treatments include, but aren’t limited to, the following:
Prevention is key for many of the conditions that can cause peripheral nervous system damage. Some of the most important things you can do include:
A note from Cleveland Clinic
Your peripheral nervous system is a key part of your life. It helps you move around and delivers vital information from your senses to your brain. Prevention is key when caring for this part of your nervous system. If you have conditions that affect your peripheral nerves, there’s a wide range of ways healthcare providers can diagnose and treat these conditions. Even with incurable conditions, it’s usually possible to limit how the symptoms of these conditions affect your life.
Last reviewed by a Cleveland Clinic medical professional on 05/25/2022.
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