Fig. 791 - Plan of upper portions of
Glossopharyngeal ,
Vagus , and
Accessory Nerve s.]]
Fig. 792 - Upper part of
Medulla Spinalis and
Hind- and
Mid-brain ; posterior aspect, exposed in situ.]]
The (Latin. '''nervus vagus''') or '''pneumogastric nerve''' is tenth of twelve paired
Cranial Nerves , and is the only nerve that starts in the
Brainstem (somewhere in the
Medulla Oblongata ) and extends, through the jugular foramen, all the way down past the
Head , right down to the
Abdomen . The vagus nerve is arguably the single most important nerve in the body.
The medieval
Latin word ''vagus'' means literally "wandering" (the words ''
Vagrant '', ''
Vagabond '', and ''
Vague '' come from the same root). It is also called the ''pneumogastric'' nerve since it supplies both the lungs and the stomach.
This nerve supplies sensory
Parasympathetic fibers to all the organs,except the suprarenal glands, from the
Neck down to the two third of the
Transverse Colon .
It also supplies motor fibers to skeletal muscles (see below)
In this capacity, it is involved in, among other things, such varied tasks as
Heart Rate , gastrointestinal
Peristalsis ,
Sweating and
Speech (via the
Recurrent Laryngeal Nerve ).
The vagus also controls a few
Skeletal Muscle s, namely:
This means that the vagus nerve is responsible for quite a few muscle movements in the mouth, and also is vitally important for speech and in keeping the larynx open for breathing.
It also receives some sensation from the
Outer Ear , where there is the Auricular branch (also known as
Alderman's Nerve ) and part of the
Meninges .
Parasympathetic innervation of the heart is mediated by the vagus nerve. The right vagus innervates the
SA Node . Parasympathetic hyperstimulation predisposes those affected to
Bradyarrhythmias . The left vagus when hyperstimulated predisposes the heart to
AV Block s.
At this location
Otto Loewi first proved that nerves secrete substances called
Neurotransmitters which have effects on receptors in target tissues. Loewi described the substance released by the vagus nerve as
Vagusstoff , which was later found to be
Acetylcholine .
The vagus nerve has three associated
Nuclei , the dorsal motor nucleus, the nucleus ambiguus and the
Solitary Nucleus .
Vagus Nerve Stimulation therapy using a pacemaker-like device implanted in the chest is a treatment used since 1997 to control
Seizure s in epilepsy patients and has recently been approved for treating drug-resistant cases of
Clinical Depression . Mild degree of intermittent VNS by daily performance of certain breathing exercises (
Pranayama ) over a period of several weeks lowers blood pressure and the heart rate in persons with elevated blood pressure and/or elevated heart rate, and may also stabilize mood and affect.
