In the
tympanic cavity
The tympanic cavity is a small cavity surrounding the bones of the middle ear. Within it sit the ossicles, three small bones that transmit vibrations used in the detection of sound.
Structure
On its lateral surface, it abuts the external auditory ...
, the
tympanic nerve
The tympanic nerve (Jacobson’s nerve) is a branch of the glossopharyngeal nerve found near the ear. It gives sensation to the middle ear, the Eustachian tube, the parotid gland, and mastoid air cells. It gives parasympathetic to supply to the ...
(a branch of
CN IX
The glossopharyngeal nerve (), also known as the ninth cranial nerve, cranial nerve IX, or simply CN IX, is a cranial nerve that exits the brainstem from the sides of the upper medulla, just anterior (closer to the nose) to the vagus nerve. Be ...
) divides into branches which, along with sympathetic fibres from the carotid plexus, form the tympanic plexus. This plexus is located on the surface of the
promontory
A promontory is a raised mass of land that projects into a lowland or a body of water (in which case it is a peninsula). Most promontories either are formed from a hard ridge of rock that has resisted the erosive forces that have removed the so ...
.
This tympanic plexus branches into:
* the
lesser petrosal nerve
The lesser petrosal nerve (also known as the small superficial petrosal nerve) is the general visceral efferent (GVE) component of the glossopharyngeal nerve (CN IX), carrying parasympathetic preganglionic fibers from the tympanic plexus to the pa ...
(preganglionic parasympathetic axons to otic ganglion)
* sensory branches to the tympanic cavity
The branches to the tympanic cavity provide sensory innervation to the mucosa of the tympanic cavity and the internal surface of the tympanic membrane. The cell bodies of these neurons are found in the
superior ganglion of the glossopharyngeal nerve.
References
External links
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Nerve plexus
Glossopharyngeal nerve