Lesser petrosal nerve
Encyclopedia
The lesser petrosal nerve consists of parasympathetic fibres. It leaves the tympanic plexus
to synapse
in the otic ganglion
, and eventually provide parasympathetic innervation to the parotid gland
.
The tympanic plexus has parasympathetic (preganglionic) roots which contribute to the lesser petrosal nerve. Parasympathetic contribution is from the tympanic nerve
which branches from the glossopharyngeal nerve
(CN IX) in the jugular foramen
.
The lesser petrosal nerve exits the temporal bone
and enters the middle cranial fossa
through the hiatus for lesser petrosal nerve
. In some individuals it instead passes through the foramen ovale
. It then exits the middle cranial fossa through foramen ovale
to the otic ganglion where its parasympathetic fibers synapse. From the otic ganglion, its fibers hitchhike with the auriculotemporal nerve
(from V3) to eventually innervate the parotid gland.
The geniculate ganglion
also communicates with the lesser petrosal nerve.
Tympanic plexus
In the tympanic cavity, the tympanic nerve divides into branches which form the tympanic plexus. This plexus is located on the surface of the promontory.This tympanic plexus gives off:* the lesser petrosal nerve...
to synapse
Synapse
In the nervous system, a synapse is a structure that permits a neuron to pass an electrical or chemical signal to another cell...
in the otic ganglion
Otic ganglion
The otic ganglion is a small, oval shaped, flattened parasympathetic ganglion of a reddish-gray color, located immediately below the foramen ovale in the infratemporal fossa. It gives innervation to the parotid gland for salivation....
, and eventually provide parasympathetic innervation to the parotid gland
Parotid gland
The paired parotid glands are the largest of the salivary glands. They are each found wrapped around the mandibular ramus, and secrete saliva through Stensen's ducts into the oral cavity, to facilitate mastication and swallowing and to begin the digestion of starches.-Location:The parotid glands...
.
The tympanic plexus has parasympathetic (preganglionic) roots which contribute to the lesser petrosal nerve. Parasympathetic contribution is from the tympanic nerve
Tympanic nerve
The tympanic nerve is a branch of the glossopharyngeal nerve found near the ear.-Path:It arises from the petrous ganglion, and ascends to the tympanic cavity through a small canal, the fossula petrosa/tympanic canaliculus, on the under surface of the petrous portion of the temporal bone on the...
which branches from the glossopharyngeal nerve
Glossopharyngeal nerve
The glossopharyngeal nerve is the ninth of twelve pairs of cranial nerves . It exits the brainstem out from the sides of the upper medulla, just rostral to the vagus nerve...
(CN IX) in the jugular foramen
Jugular foramen
The jugular foramen is a large aperture in the base of the skull. It is located behind the carotid canal and is formed in front by the petrous portion of the temporal, and behind by the occipital; it is generally larger on the right than on the left side....
.
The lesser petrosal nerve exits the temporal bone
Temporal bone
The temporal bones are situated at the sides and base of the skull, and lateral to the temporal lobes of the cerebrum.The temporal bone supports that part of the face known as the temple.-Parts:The temporal bone consists of four parts:* Squama temporalis...
and enters the middle cranial fossa
Middle cranial fossa
The middle fossa, deeper than the anterior cranial fossa, is narrow medially and widens laterally to the sides of the skull. It is separated from the posterior fossa by the clivus and the petrous crest....
through the hiatus for lesser petrosal nerve
Hiatus for lesser petrosal nerve
The hiatus for lesser petrosal nerve is a hiatus in the petrous part of the temporal bone which transmits the lesser petrosal nerve. It is located posterior to the groove for the superior petrosal sinus and posterolateral to the jugular foramen....
. In some individuals it instead passes through the foramen ovale
Foramen ovale
There are multiple structures in the human body with the name foramen ovale :* In the fetal heart, the foramen ovale is a shunt from the right atrium to left atrium....
. It then exits the middle cranial fossa through foramen ovale
Foramen ovale
There are multiple structures in the human body with the name foramen ovale :* In the fetal heart, the foramen ovale is a shunt from the right atrium to left atrium....
to the otic ganglion where its parasympathetic fibers synapse. From the otic ganglion, its fibers hitchhike with the auriculotemporal nerve
Auriculotemporal nerve
The auriculotemporal nerve is a branch of the mandibular nerve that runs with the superficial temporal artery and vein, and provides sensory innervation to various regions on the side of the head.-Origin:...
(from V3) to eventually innervate the parotid gland.
The geniculate ganglion
Geniculate ganglion
The geniculate ganglion is an L-shaped collection of fibers and sensory neurons of the facial nerve located in the facial canal of the head...
also communicates with the lesser petrosal nerve.