- Cranial Nerves 5, 7, 9, 10 213
Cranial Nerve 7: Anatomy
■ Th e facial nucleus houses special visceral eff erent
(SVE) cells and innervates the muscles of facial
expression.
■ Th e superior salivatory nucleus houses general
visceral eff erent cells (GVE) and provides
parasympathetic innervation to the pterygopalatine
and submandibular ganglia.
■ Th e solitary tract nucleus receives the special visceral
aff erent (SVA) fi bers of cranial nerve 7, which carry
taste sensation from the anterior two thirds of the
tongue.
■ Th e pars caudalis portion of the spinal trigeminal
nucleus receives the general sensory aff erent (GSA)
fi bers of cranial nerve 7, which carry sensory
information from select portions of the external ear.
■ Th e facial nerve divides into four segments: an
extracranial segment — where the nerve emerges from
the petrous portion of the temporal bone; an
intratemporal segment — where it passes through the
petrous bone; a cisternal segment — where it passes
through the cerebellopontine angle cistern; and an
intra-axial segment — its brainstem course.Cranial Nerves 9 & 10
■ Th e inferior salivatory nucleus innervates the otic
ganglion, which provides parasympathetic
innervation to the parotid gland.
■ Th e dorsal motor nucleus of the vagus provides
parasympathetic innervation to smooth muscle of the
oropharynx and parasympathetic innervation to
viscera within the thoracoabdomen.
■ Nucleus ambiguus innervates the throat muscles and
provides parasympathetic innervation to select
cardiovascular structures.
■ Th e spinal trigeminal nucleus, pars caudalis
receives a small portion of its cutaneous sensory
reception from the glossopharyngeal and vagus
nerves.
■ Th e solitary tract nucleus receives sensory aff erents
for taste, sensory aff erents from the epiglottis, and
parasympathetic aff erents from widespread
thoracoabdominal regions.
■ Th e glossopharyngeal and vagus nerves exit the
medulla through the post-olivary sulcus to enter the
cerebellomedullary cistern, and they traverse the skull
base through the jugular foramen.The Gag Refl ex
■ Th e gag refl ex relies on the glossopharyngeal nerve
for its aff erent loop and the vagus nerve for its
eff erent loop.
■ In a lower motor neuron injury (such as a direct
lesion to the nucleus ambiguus itself or its exiting
fi bers), there is unilateral palatal paralysis on the side
of the lower motor neuron lesion.