The vagus nerve is the longest cranial nerve in the body, traveling from the brain stem down through the spinal cord to the abdominal area. Along the way, it reaches out and affects many organs. Also known as cranial nerve X and the pneumogastric nerve, the vagus nerve is the primary component of the parasympathetic nervous system, which is part of the autonomic nervous system. The autonomic nervous system also includes the sympathetic nervous system.  While the sympathetic nervous system triggers the fight-or-flight response, the parasympathetic nervous system sets off a calming response after the danger has passed. Feelings of safety trigger the front (ventral) part of the vagus nerve while danger activates the back (dorsal). When a vagus nerve is healthy, it leads an individual to respond in an appropriate or mindful way. What the Vagus Nerve Does The vagus nerve is named after the Latin word for “wandering,” …