The vagus nerve originates in the brain stem and travels through organs in the neck, thorax and abdomen. Several branches of the vagus nerve connect to different parts of the stomach, stimulating the stomach to produce acid.
Sometimes, the stomach may become overstimulated and produce too much acid, causing ulcers or contributing to conditions such as gastroesophageal reflux.
Vagotomy is the surgical cutting or removal of the vagus nerve to reduce acid production in the stomach. The procedure is usually performed when acid production cannot be reduced by medication or other means. It is often performed in serious and emergency situations, such as in the presence of an ulcer.