The geniculate ganglion (from
Latin ''genu'', for "knee"
) is a collection of
pseudounipolar sensory neurons of the
facial nerve located in the
facial canal of the
head
A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may ...
. It receives fibers from the facial nerve. It sends fibers that supply the
lacrimal glands,
submandibular gland
The paired submandibular glands (historically known as submaxillary glands) are major salivary glands located beneath the floor of the mouth. They each weigh about 15 grams and contribute some 60–67% of unstimulated saliva secretion; on stimula ...
s,
sublingual gland
The paired sublingual glands are major salivary glands in the mouth. They are the smallest, most diffuse, and the only unencapsulated major salivary glands. They provide only 3-5% of the total salivary volume. There are also two other types of sal ...
s,
tongue,
palate,
pharynx,
external auditory meatus,
stapedius muscle, posterior belly of the
digastric muscle,
stylohyoid muscle, and muscles of
facial expression.
The geniculate ganglion is one of several ganglia of the head and neck. Like the others, it is a bilaterally distributed structure, with each side of the face having a geniculate ganglion.
Structure
The geniculate ganglion is located close to the
internal auditory meatus.
It is covered superiorly by the
petrous part of the temporal bone (which is sometimes absent over the ganglion).
The geniculate ganglion receives fibers from the motor, sensory, and
parasympathetic
The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of t ...
components of the facial nerve. It the contains special sensory neuronal cell bodies for
taste, from fibers coming up from the
tongue through the
chorda tympani and from fibers coming up from the roof of the
palate through the
greater petrosal nerve. Sensory and parasympathetic inputs are carried into the geniculate ganglion via the
nervus intermedius. Motor fibers are carried via the facial nerve proper. The
greater petrosal nerve, which carries preganglionic parasympathetic fibers, emerges from the anterior aspect of the ganglion.
The motor fibers of the facial nerve proper and parasympathetic fibers to the submandibular and pterygopalatine ganglia do not synapse in the geniculate ganglion. The afferent fibers carrying pain, temperature, and touch from the posterior auricular nerve, as well as those carrying special sensory (taste) fibers from the tongue (via the chorda tympani), do not synapse in the geniculate ganglion. Instead, the cells of the geniculate ganglion relay the signal to the appropriate brainstem nucleus, much like the Dorsal root ganglion neurons relay signal to nuclei in the spinal cord.
Function
Via the geniculate ganglion, the facial nerve (CN VII) gives
* parasympathetic innervation to:
** the
lacrimal glands.
** the
submandibular gland
The paired submandibular glands (historically known as submaxillary glands) are major salivary glands located beneath the floor of the mouth. They each weigh about 15 grams and contribute some 60–67% of unstimulated saliva secretion; on stimula ...
s.
** the
sublingual gland
The paired sublingual glands are major salivary glands in the mouth. They are the smallest, most diffuse, and the only unencapsulated major salivary glands. They provide only 3-5% of the total salivary volume. There are also two other types of sal ...
s.
* special sensory innervation to:
** the
tongue for
taste.
* general sensory innervation to:
** skin of the posterior ear
* somatic (branchial) motor innervation to:
** the
palate
** the
pharynx.
** the
external auditory meatus
** the
stapedius muscle.
** the posterior belly of the
digastric muscle.
** the
stylohyoid muscle.
** muscles of
facial expression.
Clinical significance
The geniculate ganglion is an important
surgical landmark near the
internal auditory meatus.
The geniculate ganglion may become
inflamed due to
viral infection by
herpes zoster virus
Varicella-zoster virus (VZV), also known as human herpesvirus 3 (HHV-3, HHV3) or ''Human alphaherpesvirus 3'' ( taxonomically), is one of nine known herpes viruses that can infect humans. It causes chickenpox (varicella) commonly affecting chi ...
.
Additional images
File:Gray788.png , Plan of the facial and intermediate nerves and their communication with other nerves.
See also
*
Ramsay Hunt syndrome type II
References
External links
* ()
* ()
{{Authority control
Nervous ganglia of the head and neck
Gustatory system
Sensory ganglia