Vagus nerve function

The Heart:

• The heart relies on sympathetic and parasympathetic innovation from the vagus nerve
• The right vagus nerve primarily inervates the sino atrial node and the left inervates the atrioventricular node. (There can be significant overlap in the anatomical distribution of these)
• Sympathetic stimulation increases heart rate, whereas parasympathetic stimulation has the opposite effect  

 Blood Vessels:

• Branches of the vagus nerve can be found in the adventita of the blood vessels
• Sympathetic activation leads to vasoconstriction of the arteries and veins allowing regulation of blood pressure and diversion of blood to other areas

 Breathing:

• The vagus nerve is responsible for keeping the larynx open for breathing and also serves the lungs and diaphragm
• Deep inhalation activates stretch receptors in the blood vessels, which stimulates the vagus nerve bringing a balance between the parasympathetic and sympathetic nervous systems

 Digestion:

• Chewing and swallowing stimulate the vagus nerve, which sends signals to the stomach to release acid for the breakdown of food
• The vagus nerve controls the movement of food from the stomach through the digestive tract i.e. peristalsis