The vagus nerve is the main parasympathetic nerve of the thorax.
The vagus nerve begins in the head exiting through the jugular foramen, passing through the carotid sheath, and descending through the neck.
- In the neck, the vagus nerve of each side runs pretty much in parallel with the other and the phrenic nerves, down to the level of the sternocostal joints
- At the level of the sternocostal joints their course changes, and has to be distinguished (see left and right vagus nerve below).