The vagus nerve interacts with the brain and is connected to motor function in the diaphragm, voice box, heart and stomach. It also affects sensory function in the tongue and ears, and both sensory and motor function in the sinuses and esophagus, according to the American Association of Neurological Surgeons.
The vagus nerve receives information from these organs and communicates it to the brain. The vagus nerve is responsible for the gut instinct of fear that people feel in a fight-or-flight situation, states Psychology Today. As part of the involuntary nervous system, the vagus nerve keeps heart rate constant and regulates food digestion, says Healthline.