The vagus nerve is a long cranial nerve divided into left and right sections. In actuality, it is a pair of intertwining nerves but experts generally refer to it as a single nerve.
The vagus nerve stretches from the brain stem to the abdomen, passing through various organs. The vagus nerve plays an important role in the involuntary nervous system and is in charge of involuntary bodily functions, such as digestion, sweating, the gag reflex, speech and the heartbeat. It also controls several skeletal muscles, including the cricothyroid muscles and the palatoglossus muscle. The vagus nerve is responsible for fainting as a bodily overreaction to certain stimuli.