The vagal nerve is part of the parasympathetic nervous system, which is responsible for maintaining homeostasis in the body. It is the longest cranial nerve, with many branches and fibers that can extend to different abdominal, thoracic and pelvic organs. In particular, the vagus nerve governs the functions of the heart, lungs and digestive system, regulating heart rate and bronchial dilation. It is also thought to be heavily involved in mediating emotions, particularly those which signal relaxation, fear or stress. The vagal nerve is a unique regulator of involuntary processes and its sophisticated interplay of innervation and regulation helps maintain a stable and balanced inner environment.

See also: nervous system, brain stem, peak experience, altered state