Vagus Nerve

What is the Vagus Nerve?

The vagus nerve, also known as the vagal nerves, are the main nerves of your parasympathetic nervous system. This system controls specific body functions such as your digestion, heart rate and immune system. These functions are involuntary, meaning you can’t consciously control them.

Your left and right vagal nerves contain 75% of your parasympathetic nervous system’s nerve fibers. These fibers send information between your brain, heart and digestive system.

The vagus nerves are the 10th of 12 cranial nerves. The vagus is known as cranial nerve X, the Roman numeral for 10.

What is the function of the vagus nerve?

Your vagal nerves are part of your body’s nervous system. They play important roles in involuntary sensory and motor (movement) functions, including:

• Digestion.
• Heart rate, blood pressure and respiration (breathing).
• Immune system responses.
• Mood.
• Mucus and saliva production.
• Skin and muscle sensations.
• Speech.
• Taste.
• Urine output.

What is the role of the parasympathetic nervous system?

Your parasympathetic nervous system controls “rest and digest” functions. It’s the opposite of your sympathetic nervous system’s “fight or flight” response.

These two nervous systems make up your autonomic nervous system. This system controls involuntary body activities.

Where is the vagus nerve?

Your vagus nerves are the longest cranial nerve, running from your brain to your large intestine. Your left vagus nerve travels down the left side of your body. The right vagus nerve travels down the right side of your body.

“Vagus” is the Latin word for wandering. Your vagal nerves take a long, winding course through your body. They exit from your medulla oblongata in your lower brainstem. Then, the nerves pass through or connect with your:

• Neck (between your carotid artery and jugular vein).
• Chest (thorax).
• Heart.
• Lungs.
• Abdomen and digestive tract.

What are the vagal nerve branches?

Your left and right vagal nerves join to form the vagal trunk. They connect at your esophageal hiatus, the opening where your esophagus passes into your abdominal cavity (belly). The vagal trunk includes anterior (front) and posterior (back) gastric nerves that go to your abdomen.

Your vagal nerve branches are:

• Inferior ganglion branch that serves nerves and muscles to your throat (pharynx) and voice box (larynx).
• Superior ganglion branch that serves nerves to your spine and ear.
• Vagus nerve branch that serves nerves to your heart, lungs and esophagus (tube connecting your mouth and stomach).

What conditions and disorders affect the vagal nerves?

Your vagus nerve can be involved with these conditions:

• Gastroparesis: Gastroparesis occurs when damage to a vagus nerve stops food from moving into your intestines from your stomach. This vagal nerve damage can result from diabetes, viral infections, abdominal surgery and scleroderma.
• Vasovagal syncope: Syncope is another word for fainting. Vasovagal syncope occurs when a vagus nerve to your heart overreacts to certain situations like extreme heat, anxiety, hunger, pain or stress. Blood pressure drops very quickly (orthostatic hypotension), making you feel dizzy or faint.

What are the signs of vagus nerve problems?

Vagus nerve conditions cause different symptoms depending on the specific cause and affected part of your nerve.

You may experience:

• Abdominal pain and bloating.
• Acid reflux (gastroesophageal reflux disease, GERD).
• Changes to heart rate, blood pressure or blood sugar.
• Difficulty swallowing or loss of gag reflex.
• Dizziness or fainting.
• Hoarseness, wheezing or loss of voice.
• Loss of appetite, feeling full quickly or unexplained weight loss.
• Nausea and vomiting.

What is vagus nerve stimulation?

Vagus nerve stimulation (VNS) uses electrical impulses to stimulate your left vagus nerve. Healthcare providers implant a small device in your chest, under your skin. A wire runs under your skin connecting the device and nerve.

The device sends mild, painless electrical signals through your left vagus nerve to your brain. These impulses calm down irregular electrical activity in your brain.

The U.S. Food and Drug Administration (FDA) has approved VNS to treat epilepsy and depression that doesn’t respond to standard therapies. It’s also being investigated for the treatment of:

• Cluster headaches.
• Inflammatory bowel disease (IBD).
• Pain.
• Post-traumatic stress disorder (PTSD).
• Rheumatoid arthritis.

How are vagus nerve disorders diagnosed?

Your healthcare provider may order one of these tests to diagnose a problem with your vagal nerves:

• CT scan or MRI to look for intestinal blockages.
• Echocardiogram to assess heart function.
• Gastric emptying solid study or smart pill (an electronic device you swallow) to gauge how long food takes to move through your stomach and into your intestines.
• Upper endoscopy to examine your upper digestive system.

What are common treatments for vagus nerve disorders?

Treatments for gastroparesis include:

• Dietary changes.
• Medicines to ease nausea and abdominal pain, regulate blood sugar and improve stomach emptying.
• Feeding tubes to deliver nutrition to your bloodstream.
• Gastrostomy to create an opening in your stomach to relieve pressure.
• Gastric electrical stimulation (similar to VNS) to send electrical impulses to muscles and nerves in your stomach and move food through your intestines.

Treatments for vasovagal syncope include:

• Consuming a high-salt diet.
• Stopping medicines that lower blood pressure, like diuretics.
• Taking medicines to increase sodium, fluid levels and blood pressure or to quiet nervous system responses.
• Wearing compression stockings to keep blood from pooling in your legs.

How can I protect my vagal nerves?

These lifestyle changes can keep your nervous system healthy:

• Be physically active.
• Eat a healthy diet.
• Manage conditions like diabetes and high or low blood pressure.
• Practice techniques such as meditation, hypnotherapy or yoga.

When should I talk to a doctor?

You should call your healthcare provider if you experience:

• Abdominal pain.
• Acid reflux.
• Difficulty swallowing or speaking.
• Fainting.
• Nausea, vomiting or unexplained weight loss.
• Rapid or slow heart rate.

A note from Cleveland Clinic

Your vagal nerves play key roles in helping your body manage involuntary functions like heart rate, breathing and digestion. Damage to your vagal nerves can cause digestive problems like gastroparesis. Healthcare providers use VNS to send electrical signals to your brain. These impulses calm down irregular electrical activity in your brain.