416
UNIT THREE
Meningeal branch
Superior ganglion
of vagus nerve
Auricular branch
Pharyngeal branch
Palate
Superior laryngeal
nerve
Recurrent laryngeal
nerve
Cardiac nerves
Heart
Liver
Kidney
Inferior ganglion
of vagus nerve
Nerve XI
Nerve XII
Carotid body
Large intestine
Left vagus
nerve
Lung
Stomach
Spleen
Pancreas
Small
intestine
FIGURE 11.28
The vagus nerves (only the left vagus is shown) extend from the medulla oblongata downward into the chest and abdomen to supply
many organs.
f
bers are sensory. These f
bers carry impulses From the lin-
ing oF the pharynx, tonsils, and posterior third oF the tongue
to the brain. ±ibers in the motor component oF the glossopha-
ryngeal nerves innervate certain salivary glands and a con-
strictor muscle in the wall oF the pharynx that Functions in
swallowing.
The tenth pair, the
vagus
(va
gus)
nerves
(X), originate
in the medulla oblongata and extend downward through the
neck into the chest and abdomen. These nerves are mixed,
including both somatic and autonomic branches, with the
autonomic f
bers predominant.
Among the somatic components oF the vagus nerves are
motor f bers that carry impulses to muscles oF the larynx. These
f bers are associated with speech and swallowing refl exes that
employ muscles in the soFt palate and pharynx. Vagal sensory
f bers carry impulses From the linings oF the pharynx, larynx,
and esophagus and From the viscera oF the thorax and abdo-
men to the brain. Autonomic motor f bers oF the vagus nerves
supply the heart and many smooth muscles and glands in the
viscera oF the thorax and abdomen
(f g. 11.28)
.
The eighth pair, the
vestibulocochlear
(ves-tib
u-lo-
kok
le-ar)
nerves
(VIII, acoustic, or auditory, nerves), are
sensory nerves that arise From the medulla oblongata. Each
oF these nerves has two distinct parts—a vestibular branch
and a cochlear branch.
The neuron cell bodies oF the
vestibular branch
f
bers are
located in ganglia near the vestibule and semicircular canals
oF the inner ear. These structures contain receptors that
sense changes in the position oF the head and, in response,
initiate and send impulses to the cerebellum, where they are
used in refl
exes that maintain equilibrium.
The neuron cell bodies oF the
cochlear branch
f bers are
located in a ganglion oF the cochlea, a part oF the inner ear
that houses the hearing receptors. Impulses From this branch
pass through the medulla oblongata and midbrain on their
way to the temporal lobe, where they are interpreted.
The ninth pair, the
glossopharyngeal
(glos
o-Fah-
rin
je-al)
nerves
(IX), are associated with the tongue and
pharynx. These nerves arise From the medulla oblongata,
and, although they are mixed nerves, their predominant
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