The vagus nerve, also known as the pneumogastric nerve, is a nerve that runs from the brain to the abdomen, and along its path, it gives rise to several branches that innervate several cervical, thoracic and abdominal organs, with sensory and motor functions, being important for the maintenance of vital functions, such as heart rate and arterial regulation, for example.
The pair of vagus nerves, located on each side of the body, are the 10th pair of a total of 12 cranial pairs that connect the brain to the body. Since cranial nerves are referred to as Roman numbers, the vagus nerve is also called the X pair, and is considered the longest of the cranial nerves.
Certain stimuli to the vagus nerve, caused by anxiety, fear, pain, changes in temperature or simply by standing for a long time, can cause the so-called vasovagal syncope, in which the person may experience intense dizziness or fainting, as this nerve can cause a drop in heart rate and blood pressure. Understand what vasovagal syncope is and how to treat it.
Anatomy of the vagus nerve
The vagus nerve is the largest cranial nerve and originates at the back of the spinal bulb, a brain structure that connects the brain with the spinal cord, and leaves the skull through an opening called the jugular foramen, descending through the neck and chest until it ends in the stomach.
During the course of the vagus nerve, it innervates the pharynx, larynx, heart and other organs, and it is through it that the brain perceives how these organs are and regulates several of their functions.
Main functions
Some of the main functions of the vagus nerve include:
- Reflexes of coughing, swallowing and vomiting; Contraction of the vocal cords for the production of the voice; Control of the contraction of the heart; Decreased frequency of the heartbeat; Respiratory movements and constriction of the bronchi; Coordination of the movements of the esophagus and intestine, and increased secretion gastric; Sweat production.
In addition, the vagus nerve shares some of its functions with the glossopharyngeal nerve (IX pair), especially in the neck region, being responsible for the gustatory sensation, where the vagus nerve is more related to sour and glossopharyngeal with a bitter taste.
Vagus nerve changes
A vagus nerve palsy can cause difficulties in swallowing, hoarseness, difficulties in speaking, contractions in the muscles of the pharynx and larynx, and changes in blood pressure and heartbeat. This paralysis can occur due to trauma, injuries in surgeries, compressions by tumors or certain neurological syndromes.
In addition, there are situations that cause excessive stimulation of the vagus nerve, generating a situation called vagal syncope or fainting. It usually occurs in young individuals and is due to reduced heart rate and blood pressure due to lack of oxygen in the brain, causing fainting. See what to do in case of fainting.
Vagal syncope can be caused by:
- Exposure to heat; Strong emotions, such as anger; Persist for a long time standing; Changes in temperature; Swallowing very large foods; Being at a high altitude; Feeling hungry, pain, or other unpleasant experiences.
The stimulation of the vagus nerve can also be done through a massage on the side of the neck. Sometimes the vagal maneuver is done by doctors in an emergency to regularize cardiac arrhythmia.
