Structure and Function of the Vagus Nerve
- Vagus nerve extends through the jugular foramen and passes into the carotid sheath
- Innervates the viscera
- Sensory fibers originate from neurons of the nodose ganglion
- Motor fibers come from neurons of the dorsal motor nucleus of the vagus and the nucleus ambiguus
- Supplies motor parasympathetic fibers to organs
- Controls skeletal muscles in the mouth
- Responsible for heart rate, gastrointestinal peristalsis, and sweating
- Innervates the inner portion of the outer ear and part of the meninges
- Regulates inflammation in the body

Cardiac and Urogenital Effects of the Vagus Nerve
- Parasympathetic innervation of the heart is controlled by the vagus nerve
- Vagal and spinal ganglionic nerves lower the heart rate
- Right vagus branch innervates the sinoatrial node
- Hyperstimulation of parasympathetic influence promotes bradyarrhythmias
- Left vagal branch predisposes the heart to conduction block at the atrioventricular node
- Excessive activation of the vagal nerve during emotional stress can cause vasovagal syncope
- Vasovagal syncope affects young children and women more than other groups
- Can lead to temporary loss of bladder control under extreme fear
- Women with complete spinal cord injury can experience orgasms through the vagus nerve
- Insulin signaling activates ATP-sensitive potassium channels and decreases glucose production by the liver

Clinical Significance of the Vagus Nerve
- Anticholinergic drugs inhibit the action of the vagus nerve on the heart and other organs
- Drugs that inhibit muscarinic receptors increase heart rate and treat bradycardia
- Vasovagal syncope can cause a sudden drop in cardiac output and cerebral hypoperfusion
- Vagus nerve stimulation can be used to treat certain neurological disorders
- Vagus nerve plays a role in the regulation of inflammation and satiation

Stimulation of the Vagus Nerve
- Vagus nerve stimulation (VNS) therapy has been used to control seizures in epilepsy patients and treat drug-resistant clinical depression
- Noninvasive VNS devices that stimulate the vagus nerve are available
- VNS can also be achieved through vagal maneuvers such as holding the breath, dipping the face in cold water, coughing, humming or singing, or tensing the stomach muscles
- Patients with certain illnesses may be trained to perform vagal maneuvers
- Vagus nerve blocking (VBLOC) therapy is similar to VNS but used only during the day and has shown promising results in weight loss

Vagus Nerve Pathology and Other Health Conditions
- Vagotomy, a now obsolete therapy, was performed for peptic ulcer disease but has been superseded by oral medications
- Vagotomy is being researched as a less invasive alternative weight-loss procedure to gastric bypass surgery
- Vagus nerve dysfunction can cause various symptoms throughout the body due to its control over the autonomic nervous system
- Vagus nerve involvement in cluster headaches
- Vagus nerve involvement in Parkinson's disease
- Vagus nerve cough reflex and chronic cough
- Potential role of the vagus nerve in pernicious anemia