To carotid sinus and
Vagus nerve (X)
Pharyngeal nerve branch
Aortic arch baroreceptor
and aortic body
IX Glossopharyngeal Nerves
Origin and course:
Fibers emerge from medulla and leave skull via
to run to throat.
Mixed nerves that innervate part of tongue and pharynx.
Provide somatic motor ﬁbers to, and carry proprioceptor ﬁbers from,
a superior pharyngeal muscle called the
elevates the pharynx in swallowing. Provide parasympathetic motor
ﬁbers to parotid salivary glands (some of the nerve cell bodies of
these parasympathetic motor neurons are located in
Sensory ﬁbers conduct taste and general sensory (touch, pressure, pain)
impulses from pharynx and posterior tongue, from chemoreceptors in
the carotid body (which monitor O
levels in the blood and help
regulate respiratory rate and depth), and from baroreceptors of carotid
sinus (which monitor blood pressure). Sensory neuron cell bodies are
Check position of uvula; check gag and swallowing
reﬂexes. Ask subject to speak and cough. Test posterior third of
tongue for taste.
Injured or inﬂamed
glossopharyngeal nerves impair swallowing and taste.
X Vagus Nerves
Origin and course:
The only cranial nerves to extend beyond head
and neck region. Fibers emerge from medulla, pass through skull via
jugular foramen, and descend through neck region into thorax and
abdomen. See also Figure 14.4.
Mixed nerves. Nearly all motor ﬁbers are parasympathetic
efferents, except those serving skeletal muscles of pharynx and
larynx (involved in swallowing). Parasympathetic motor ﬁbers supply
heart, lungs, and abdominal viscera and are involved in regulating
heart rate, breathing, and digestive system activity. Transmit sensory
impulses from thoracic and abdominal viscera, from the aortic arch
baroreceptors (for blood pressure) and the carotid and aortic bodies
(chemoreceptors for respiration), and taste buds on the epiglottis.
Carry proprioceptor ﬁbers from muscles of larynx and pharynx.
As for cranial nerve IX (glossopharyngeal; IX and X
are tested in common, since they both innervate muscles of throat
Since laryngeal branches
of the vagus innervate nearly all muscles of the larynx (“voice
box”), vagal nerve paralysis can lead to hoarseness or loss of voice.
Other symptoms are difﬁculty swallowing and impaired digestive
system motility. These parasympathetic nerves are important for
maintaining the normal state of visceral organ activity. Without their
inﬂuence, the sympathetic nerves, which mobilize and accelerate
vital body processes (and shut down digestion), would dominate.