Tympanic nerve
Encyclopedia
The tympanic nerve is a branch of the glossopharyngeal nerve
found near the ear.
, 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 ridge which separates the carotid canal
from the jugular fossa
.
In the tympanic cavity it divides into branches which form the tympanic plexus
and are contained in grooves upon the surface of the promontory.
Jacobson's nerve contains both sensory and secretory fibers.
The postganglionic parasympathetic fibers are then distributed via the auriculotemporal nerve
(branch of the trigeminal nerve
) to the parotid gland
.
, in this location referred to as glomus jugulare or glomus tympanicum tumours.
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...
found near the ear.
Path
It arises from the petrous ganglionPetrous ganglion
The inferior ganglion of the glossopharyngeal nerve is larger than the superior ganglion and is situated in a depression in the lower border of the petrous portion of the temporal bone....
, and ascends to the tympanic cavity
Tympanic cavity
The tympanic cavity is a small cavity surrounding the bones of the middle ear.It is formed from the tubotympanic recess, an expansion of the first pharyngeal pouch....
through a small canal, the fossula petrosa/tympanic canaliculus, on the under surface of the petrous portion of 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...
on the ridge which separates the carotid canal
Carotid canal
On the interior surface of the temporal bone, behind the rough surface of the apex, is the large circular aperture of the carotid canal, which ascends at first vertically, and then, making a bend, runs horizontally forward and medialward.-Contents:...
from the jugular fossa
Jugular fossa
The jugular fossa is a deep depression in the inferior part of the base of the skull. More specifically, it is located in the temporal bone, posterior to the carotid canal and the aquæductus cochleæ...
.
In the tympanic cavity it divides into branches which form the tympanic plexus
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...
and are contained in grooves upon the surface of the promontory.
Jacobson's nerve contains both sensory and secretory fibers.
- Sensory fibers supply the middle ear.
- Parasympathetic secretory fibers continue as the Lesser Petrosal nerveLesser petrosal nerveThe 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....
and provide secretomotor innervation to the parotid gland. The secretory fibers enter the otic ganglionOtic ganglionThe 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....
. - Sympathetic fibers (for the large deep petrosal nerve) through communication with the carotid plexus
The postganglionic parasympathetic fibers are then distributed via 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:...
(branch of the trigeminal nerve
Trigeminal nerve
The trigeminal nerve contains both sensory and motor fibres. It is responsible for sensation in the face and certain motor functions such as biting, chewing, and swallowing. Sensory information from the face and body is processed by parallel pathways in the central nervous system...
) 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...
.
Clinical significance
This nerve may be involved by paragangliomaParaganglioma
A paraganglioma is a rare neuroendocrine neoplasm that may develop at various body sites . About 97% are benign and cured by surgical removal; the remaining 3% are malignant because they are able to produce distant metastases...
, in this location referred to as glomus jugulare or glomus tympanicum tumours.