What Is the Peripheral Nervous System? Everything to Know

Your peripheral nervous system (PNS) includes all the nerves in your body that send signals to and from your central nervous system. Its primary function is communication with your brain and the rest of your body, such as your skin, muscles, and organs.  The organs of your peripheral nervous system include nerves and ganglia, which pick up sensory information from your environment. The peripheral nervous system communicates with the brain by converting this information to electrical signals called nerve impulses.

This article looks at how the peripheral nervous system works and what health conditions affect it. 

Your nervous system is your control center regulating and communicating with all the systems in your body. It is your center for learning, memories, and thoughts. Together with the endocrine system, your nervous system maintains homeostasis, where your body systems are balanced.

Although just one system, your nervous system is subdivided into the central nervous system (CNS) and peripheral nervous system (PNS). Your CNS contains your brain and spinal column.

Your PNS includes all the nerves and ganglia that branch from your brain and spinal column. Both parts work together to keep your body in touch with your environment internally and externally. 

Your PNS contains millions of receptors that detect changes occurring inside and outside your body. They monitor things such as:

• temperature
• light
• sounds
• pH
• carbon dioxide concentration
• levels of various electrolytes 

Your PNS converts the sensory input to electrical nerve impulses and sends the information to the brain, where responses are created and sent back through the PNS. The PNS may cause reactions such as

• muscles movement
• gland secretion
• blood pressure change
• increase or decrease in heart rate

Your PNS is divided into the autonomic nervous and somatic nervous systems.

The autonomic nervous system is responsible for regulating automatic processes such as:

• heart rate
• blood pressure
• breathing
• digestion
• sexual arousal

The autonomic nervous system is also in charge of your fight or flight response, which takes over when your brain senses danger. 

Your somatic nervous system is responsible for the voluntary movement of your muscles. These include all movements you are aware of, such as the movement of your arms, legs, and other parts of your body.

The somatic nervous system also contains sensory nerves and is responsible for your reflexes. 

A nerve cell or neuron contains a cell body that holds the nucleus. An axon is a long extension off the cell body containing bundles of nerve fibers surrounded by connective tissue. On the end of the axon are dendrites, which communicate with other nerve cells. 

Certain neurons control motor functions, such as generating movement in our muscles, while other neurons are sensory and detect such things as touch, light, sound, or taste. 

There are 12 pairs of cranial nerves that branch out from the front of your brain. They control your senses and the movement of your facial muscles. 

There are 31 pairs of spinal nerves that branch from the spinal cord. These nerves extend to all your internal organs and arms, and legs. 

Several conditions can affect the peripheral nervous system. These conditions can cause problems with your movement and ability to sense things. 

Amyotrophic lateral sclerosis (ALS) is a rare neurological disease that occurs when the nerves responsible for controlling voluntary muscle movements gradually deteriorate and die.

The condition is progressive, which means the symptoms worsen over time. Currently, there is no cure for ALS and no treatment able to stop or reverse the progression of the weakness. However, some treatments can help to alleviate symptoms.

Peripheral neuropathy refers to several conditions resulting from damage to the nerves of the PNS.

Possible causes of damage to the nerve signaling include:

• trauma
• diabetes
• blood flow problems
• autoimmune disorders

The damage may cause weakness or a loss of sensation in an area. 

Carpal tunnel syndrome happens when the median nerve in your forearm becomes pressed or squeezed at the wrist.

The squeeze may be from thickening from irritated tendons or other swelling. This can cause weakness, numbness, and pain. 

Guillain-Barré syndrome occurs when a person’s immune system causes damage to their nerves. This can cause muscle weakness and sometimes paralysis.

Symptoms start as weakness and tingling in the feet and legs and progress upward over hours, days, or weeks. The condition can happen because of a reaction to a vaccine or virus. 

Other conditions that may affect the PNS include:

• lupus
• diabetes
• Epstein-Barr virus
• rheumatoid arthritis
• thoracic outlet syndrome
• tumors
• vitamin D deficiency

Conditions that affect the PNS cause symptoms such as:

• numbness
• tingling
• loss of feeling
• pain
• burning
• skin sensitivity
• weakness
• complete loss of mobility

Your peripheral nervous system is an essential part of your functioning.

Contact your doctor if you’re experiencing symptoms of problems with your nerves. This can include weakness, loss of sensation, or numbness.

To diagnose PNS conditions, your doctor may ask questions about your symptoms and whether you’ve noticed anything that can trigger or relieve them. They may also ask about your medical history and any medications you’re taking.

Your doctor may then conduct a physical exam. The physical exam can include a neurological exam, where your doctor may ask you to perform some movements. They may also press on areas of your feet, legs, hands, and arms and ask whether you feel them pressing. 

Further testing they may order includes:

• lab tests
• genetic tests
• nerve conduction velocity tests
• electromyography
• nerve biopsy
• imaging studies such as MRI or CT scan

Treatment depends on the cause of the nerve damage, symptoms, and location.

Certain medications may alleviate some symptoms of nerve damage, such as tingling or a “pins and needles” feeling. Your doctor can advise on which medications they recommend for your symptoms.

Mechanical aids may help to reduce pain or physical disability. These can include hand or foot braces, orthopedic shoes, and splints.

Transcutaneous electrical nerve stimulation (TENS) is a noninvasive method of pain relief for many conditions. It uses electrodes you attach to your skin at or near the site of the pain. The TENS machine then sends a gentle electrical current that can help to reduce the pain.

Some types of neuropathy benefit from surgical procedures. Your doctor can advise on whether they recommend surgery for your condition.

Complementary methods such as acupuncture, massage, herbal remedies, cognitive behavioral, and other psychotherapy approaches may help you manage pain. You may wish to contact your doctor for advice before starting any complementary or alternative therapies. 

Although some damage is not preventable, you can take steps to reduce your risk of nerve damage. These include:

• maintaining a moderate weight
• avoiding toxic exposures
• consuming a balanced diet
• getting enough regular exercise
• quitting smoking if you smoke
• controlling your blood glucose levels

Your peripheral nervous system (PNS) is a network of nerves connected to your spine and brain. They are responsible for several important functions, such as muscle movement, maintaining homeostasis in your body, and sensing the environment around you. 

Several conditions affect the PNS. They can cause numbness, tingling, pain, or weakness. 

Maintaining a moderate weight, eating a balanced diet, and regular exercise can help lower your risk of peripheral nerve damage. 

Contact your doctor if you experience symptoms of conditions affecting your PNS. They can conduct tests to reach a diagnosis and advise on treatments.