“The vagus nerve passes out of the cerebral region as a portion of the voluntary system, and through it we control the vocal organs; then it passes onward to the thorax sending out branches to the heart and lungs; finally, passing through the diaphragm, it loses the outer coating which distinguishes the nerves of the voluntary system and becomes identified with those of the sympathetic system, so forming a connecting link between the two and making the man physically a single entity.
