2-Minute Neuroscience: Vagus Nerve (Cranial Nerve X)
The vagus nerve is a long cranial nerve that stretches from the brainstem to the colon and is involved in an extensive list of functions. In this video, I summarize …
The vagus nerve is an extremely long nerve
that travels from the brainstem to the colon
and has a long list of functions.
It carries sensory information about pain,
touch, and temperature from the throat, parts
of the inner and outer ear, and the meninges
near the back of the head.
It plays a very minor role in taste.
It also receives sensory information from
internal organs in the neck, chest and abdomen
like the esophagus, heart, and digestive tract.
And it carries sensory information from both
baroreceptors in the aorta that detect changes
in blood pressure, and chemoreceptors in the
aorta that sense oxygen levels in the blood.
The vagus nerve controls the movement of a
number of muscles in the pharynx, soft palate,
and larynx (as well as one muscle in the tongue)
to play a critical role in the control of
speaking and swallowing.
It is also the main parasympathetic nerve
of the body, providing parasympathetic innervation
to organs throughout the neck, thorax, and
abdomen, contributing to a variety of functions
such as slowing of the heart rate.
There are several nuclei in the medulla associated
with the vagus nerve and the different types
of information it carries.
Information about touch, pain, and temperature
travels to the spinal trigeminal nucleus.
Sensory information from internal organs,
or visceral sensory information, travels to
the solitary nucleus.
Motor signals originate in the nucleus ambiguus.
Parasympathetic fibers originate primarily
in the dorsal vagal motor nucleus, while some
parasympathetic fibers that travel to the
heart begin in the nucleus ambiguus.
Symptoms of vagus nerve damage may include
hoarseness of the voice, difficulty swallowing,
and a deficient gag reflex.
The uvula may deviate away from the side where
the damage has occurred.
Because the nerve supplies a number of organs,
however, damage can result in many other symptoms
as well, like abnormalities in heart rate
or gastrointestinal problems.