The Vagus nerve is the 10th and longest cranial nerve in the body. It runs all the way from the brain stem to the colon, and its known to have input to the tongue, pharynx, heart, and the gastrointestinal system. As such, it mediates swallowing, taste, and speaking. It also provides involuntary muscle control of the heart, lungs, and esophagus. In addition, it innervates the glands throughout the gastrointestinal tract. While the word nerve implies one nerve, in total there are four branches of the vagus nerve.