There are 12 cranial nerves in the body. They come in pairs and help link the brain with other areas of the body, such as the head, neck, and torso.
Some send sensory information, including details about smells, sights, tastes, and sounds, to the brain. These nerves have sensory functions. Other cranial nerves control the movement of various muscles and the function of certain glands. These are known as motor functions.
While some cranial nerves have either sensory or motor functions, others have both. The vagus nerve is such a nerve. The cranial nerves are classified using Roman numerals based on their location. The vagus nerve is also called cranial nerve X.
Explore the diagram below to see the location of the vagus nerve.
What does the vagus nerve affect?
The vagus nerve also called the pneumogastric nerve, is responsible for various internal organ functions, including:
- heart rate
- cardiovascular activity
- reflex actions, such as coughing, sneezing, swallowing, and vomiting
It plays a role in the autonomic nervous system, which controls actions people do unconsciously, such as breathing and digestion.
It may also form a link between the gut and the brain, playing a role in what scientists call the gut-brain axis. In recent years, experts have been studying the gut-brain axis to look for links between conditions such as obesity and depression.
The word “vagus” means wandering in Latin. This is a very appropriate name, as the vagus nerve is the longest cranial nerve. It runs from the brain stem to part of the colon.
The vagus nerve sensory functions are divided into two components:
- Somatic components. These are sensations felt on the skin or in the muscles.
- Visceral components. These are sensations felt in the organs of the body.
Sensory functions of the vagus nerve include:
- providing somatic sensation information for the skin behind the ear, the external part of the ear canal, and certain parts of the throat
- supplying visceral sensation information for the larynx, esophagus, lungs, trachea, heart, and most of the digestive tract
- playing a small role in the sensation of taste near the root of the tongue
Motor functions of the vagus nerve include:
- stimulating muscles in the pharynx, larynx, and the soft palate, which is the fleshy area near the back of the roof of the mouth
- stimulating muscles in the heart, where it helps to lower resting heart rate
- stimulating involuntary contractions in the digestive tract, including the esophagus, stomach, and most of the intestines, which allow food to move through the tract
To test the vagus nerve, a doctor may check the
If the person does not gag, this may be due to a problem with the vagus nerve, which could indicate a problem with the brainstem function.
Doctors may also assess vagal nerve function when looking at cardiovascular disease, as discussed in recent research. Damage to the vagal nerve can lead to problems with the cardiovascular system.
Measuring heart rate, blood pressure, and cardiovascular response to exercise
Damage to the vagus nerve can result in a range of symptoms because the nerve is so long and affects many areas.
- difficulty speaking
- loss or change of voice
- difficulty swallowing
- loss of the gag reflex
- low blood pressure
- slow heart rate
- changes in the digestive process
- nausea or vomiting
- abdominal bloating or pain
- depression and anxiety in people with breathing problems or heart disease
The symptoms someone might have depend on what part of the nerve is damaged.
Experts believe that damage to the vagus nerve may also cause a condition called gastroparesis. This condition affects the involuntary contractions of the digestive system, which prevents the stomach from properly emptying.
Symptoms of gastroparesis include:
- nausea or vomiting, especially vomiting undigested food hours after eating
- loss of appetite or feeling full shortly after starting a meal
- acid reflux
- abdominal pain or bloating
- unexplained weight loss
- fluctuations in blood sugar
Some people develop gastroparesis after undergoing a vagotomy procedure, which removes all or part of the vagus nerve.
The vagus nerve stimulates certain muscles in the heart that help to slow heart rate. When it overreacts, it can cause a sudden drop in heart rate and blood pressure, resulting in fainting. This is known as
Factors that can trigger this include pregnancy, emotional stress, and pain, but there may be no clear cause.
Alongside this type of fainting, you may experience:
- tunnel vision
- ringing in the ears
- excessive sweating
- low blood pressure
- slow or irregular heartbeat
If you experience fainting, it’s a good idea to see a doctor to rule out potential serious causes. To prevent it, a doctor may recommend drinking plenty of fluids or avoiding standing up quickly.
Vagus nerve stimulation (VNS) involves placing a device in the body that uses electrical impulses to stimulate the nerve. It’s used to treat some cases of epilepsy and depression that don’t respond to other treatments.
The device is usually placed under the skin of the chest, where a wire connects it to the left vagus nerve. Once the device is activated, it sends signals through the vagus nerve to your brainstem, transmitting information to your brain.
A neurologist usually programs the device, but people often receive a handheld magnet they can use to control the device on their own as well.
Experts are keen to learn more about the vagus nerve, as it may hold clues to various health issues.
Mental health and well-being
If VNS can help manage depression, some people have been looking into various ways of stimulating the vagus nerve to boost mental well-being.
- diaphragmatic breathing techniques
- cold water immersion
- the use of transcutaneous VNS devices
Vagal response reduces with age, according to
However, there is not enough evidence to prove that all these devices and techniques are safe and effective for everyone. Always speak with a doctor before trying a new treatment strategy, as it may not be suitable for you.
There is some evidence that VNS can help reduce the severity of rheumatoid arthritis (RA), an anti-inflammatory condition that causes pain and swelling in the joints and other symptoms throughout the body.
While promising, more studies are needed to confirm that VNS can help manage RA safely and effectively in a wider population.
The vagus nerve plays a role in many bodily functions, and it may form a link between areas such as the brain and the gut. Treatments that focus on the vagus nerve have proved to help people with epilepsy and depression, and it shows promise for rheumatoid arthritis, too.
Some experts believe that further research may offer clues to managing diabetes, obesity, heart disease, and other conditions that involve inflammatory processes.