Where is the vagus nerve?
Everywhere.
The vagus nerve is a cranial nerve, so it emerges from part of the brain stem called the medulla.
It leaves the cranium and loops around the first neck bone (the atlas), affecting the tongue, the palate and the voicebox before heading down the neck and into the body. Think how your voice changes when you’re worried, and how hard it is to swallow.
It pierces the diaphragm ‘hand in hand’ with the main blood supply (aorta) and then sends connections to all the internal organs… and then it sends connections back again so that the brain hears what the system is doing. The signal feeds back and self-corrects, to finesse the response to the environment.
This wandering pathway, connecting everything with everything, makes sense when we think about how all-encompassing the horse’s response to a signal from the vagus has to be. There’s no point speeding up your heart if your eyes aren’t set to hyper-drive and your gut is still using all the blood your muscles need to run.
It’s everything, and so it’s everywhere.