Either of a pair of nerves that extend from the brain to the heart, lungs, stomach, and other organs of the body: The vagi consist of mixed nerves that have motor and sensory functions and a wider distribution than any of the other cranial nerves.

As students of neural anatomy, the class attended a lecture about the vagi which involved their normal and abnormal functions.

Vague, diffuse, or fleeting pains in the chest or abdomen: Because Jill complained of a tenderness in the area of her stomach that did't seem to get better, her parents took her to see Dr. Match who diagnosed her as having a condition of dolor vagus which involved the vagus nerve.

1. Either of the longest pair of cranial nerves mainly responsible for parasympathetic control (activities that occur when the body is at rest) over the heart and many other internal organs, including thoracic and abdominal viscera or abdominal cavity below the diaphragm but not including the pelvic tissues: The nervi vagi communicate through thirteen main branches, connecting to four areas in the brain.
2. Etymology: from Latin, vagus, "wandering" + nervus, "nerve".

A nerve that supplies nerve fibers to the pharynx (throat), larynx (voice box), trachea (windpipe), lungs, heart, esophagus (passage from the mouth to the stomach), and the intestinal tract; as far as the transverse part of the colon: The vagus nerve emerges from the medulla oblongata (part of the brain stem) and it is classified as a cranial nerve because it comes from that brain stem.

The vagus nerve transmits sensory information back to the brain from major organs in the body; including the ears, the tongue, the pharynx, the larynx, and much of the digestive system.

A complete interruption of the vagus nerve causes a condition in which the voice is hoarse and nasal, and the vocal cord on the affected side is immobile; resulting in difficulty in swallowing (dysphagia) and speaking (dysphonia).

The vagus nerve also stimulates the production of stomach acid and pancreatic juice; stimulates the activity of the gallbladder, and increases the rhythmic muscular contractions that move food through the digestive tract.

A decreased heart rate caused by the slowing action of stimuli from the vagus nerve: Jane, the nurse, checked Larry's pulse and was able to identify the vagus pulse which was causing the slow rhythmic dilation of the artery in his wrist.