The Vagus nerve is tenth of twelve cranial nerves and the only nerve that starts in the brainstem (somewhere in the medulla oblongata) and extends way down past the head, all the way down to the abdomen.
It was for this reason that it was so named, for "the wanderer" (the words "vagrant" and "vagabond" come from the same Latin word).
This nerve supplies motor and sensory parasympathetic fibres to pretty much everything from the neck down to the first third of the transverse colon. This nerve is responsible, amongst other things, such varied tasks as moderating the heart rate, gastrointestinal peristalsis, sweating and speech (via the recurrent laryngeal nerve). I cannot overstate how important this is.
As if those rather important functions weren't enough, the vagus nerve also controls a few skeletal muscles, namely:
The vagus is responsible for quite a few muscle movements in the mouth and also is vitally important for speech and in keeping the larynx open for breathing.
It also receives some sensation from the outer ear and part of the meninges.
Arguably the single most important nerve in the body.
Cranial nerves
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