Tympanic nerve
{{Short description|Branch of the glossopharyngeal nerve}}
{{Infobox nerve
| Name = Tympanic nerve
| Latin = nervus tympanicus
| Image = Gray791.png
| Caption = Plan of upper portions of glossopharyngeal, vagus, and accessory nerves. (Tympanic nerve visible in upper right)
| Image2 = Gray779.png
| Caption2 = Tympanic nerve (labelled right side)
| Innervates =
| BranchFrom =
| BranchTo = Tympanic plexus
}}
The tympanic nerve (Jacobson's nerve) is a branch of the glossopharyngeal nerve passing through the petrous part of the temporal bone to reach the middle ear. It provides sensory innervation for the middle ear, the Eustachian tube, the parotid gland, and mastoid cells. It also carries parasympathetic fibers destined for the parotid gland.
Structure
The tympanic nerve contains sensory axons to the middle ear (including the internal surface of the tympanic membrane) whose cell bodies are lodged in the superior ganglion of the glossopharyngeal nerve.{{Verify source|date=August 2023}}
It also contains parasympathetic axons which continue as the lesser petrosal nerve to the otic ganglion, which itself gives off postganglionic parasympathetic neurons.{{Verify source|date=August 2023}}
= Origin =
The tympanic nerve arises from the inferior ganglion of the glossopharyngeal nerve (CN IX){{Cite book|last1=Tubbs|first1=R. Shane|chapter-url=https://www.sciencedirect.com/science/article/pii/B9780124103900000275|title=Nerves and Nerve Injuries|last2=Shoja|first2=Mohammadali|last3=Loukas|first3=Marios|publisher=Academic Press|year=2015|isbn=978-0-12-410390-0|volume=1: History, Embryology, Anatomy, Imaging, and Diagnostics|pages=371–383|language=en|chapter=26 - Anatomy of the Glossopharyngeal Nerve|doi=10.1016/B978-0-12-410390-0.00027-5}} in the jugular fossa.{{Cite book |last=Sinnatamby |first=Chummy S. |title=Last's Anatomy |publisher= |year=2011 |isbn=978-0-7295-3752-0 |edition=12th |pages=366}}
= Course =
It passes through the petrous part of the temporal bone within the tympanic canaliculus that is situated within the bony ridge separating the carotid canal and the jugular foramen to reach the middle ear.
In the tympanic cavity of the middle ear, it ramifies upon the promontory of tympanic cavity to form the tympanic plexus.{{Verify source|date=August 2023}}
= Distribution =
== Sensory ==
The tympanic nerve provides sensation to the middle ear (tympanic cavity). This includes the internal surface of the tympanic membrane. It also supplies the Eustachian tube, the parotid gland, and mastoid air cells.
== Parasympathetic autonomic ==
The tympanic nerve is also the parasympathetic root of the otic ganglion.{{Cite book |last1=Thomas |first1=P. K. |title=Peripheral Neuropathy |last2=Mathias |first2=Christopher J. |publisher=Saunders |year=2005 |isbn=978-0-7216-9491-7 |edition=4th |volume=2 |pages=1273–1293 |language=en |chapter=52 - Diseases of the Ninth, Tenth, Eleventh, and Twelfth Cranial Nerves |doi=10.1016/B978-0-7216-9491-7.50055-7 |chapter-url=https://www.sciencedirect.com/science/article/pii/B9780721694917500557}} These neurons then provide secretomotor innervation of the parotid gland via the auriculotemporal nerve. It is involved in the salivatory reflex to increase salivation during chewing.{{Cite book|last1=Barral|first1=Jean-Pierre|chapter-url=https://www.sciencedirect.com/science/article/pii/B9780702031007500240|title=Manual Therapy for the Cranial Nerves|last2=Croibier|first2=Alain|publisher=Churchill Livingstone|year=2009|isbn=978-0-7020-3100-7|pages=181–189|language=en|chapter=21 - Glossopharyngeal nerve|doi=10.1016/B978-0-7020-3100-7.50024-0}}
= Variation =
The tympanic nerve usually arises from the inferior ganglion of the glossopharyngeal nerve. Rarely, it may arise from a higher part.{{Verify source|date=August 2023}} Rarely, it may provide no parasympathetic fibres to the otic ganglion.
Clinical significance
The tympanic nerve is involved in a reflex, where stimulation of the ear canal increases salivation.
= Cancer =
The tympanic nerve may be involved by paraganglioma, in this location referred to as a glomus tympanicum tumour.{{Cite book|last1=Weissleder|first1=Ralph|chapter-url=https://www.sciencedirect.com/science/article/pii/B978032306538200007X|title=Primer of Diagnostic Imaging|last2=Wittenberg|first2=Jack|last3=Harisinghani|first3=Mukesh G.|last4=Chen|first4=John W.|publisher=Mosby|year=2011|isbn=978-0-323-06538-2|edition=5th|pages=427–461|language=en|chapter=7 - Head and Neck Imaging|doi=10.1016/B978-0-323-06538-2.00007-X}} This causes a soft mass in the middle ear (tympanic cavity). There may also be pulsatile tinnitus, hearing loss or hearing problems, and some cardiac abnormalities.
History
Additional images
File:Gray782_updated.png|Lesser petrosal nerve
File:Gray843.png|Sympathetic connections of the otic and superior cervical ganglia.
References
{{Gray's}}
External links
- [https://www.google.co.in/search?q=Tympanic+nerve&es_sm=91&tbm=isch&imgil=HeO-Y6Rm4CrmzM%253A%253B4WLgrkozQUcLuM%253Bhttps%25253A%25252F%25252Fwww.studyblue.com%25252Fnotes%25252Fnote%25252Fn%25252Fneuroanatomy-lecture-14-%25252Fdeck%25252F6432334&source=iu&pf=m&fir=HeO-Y6Rm4CrmzM%253A%252C4WLgrkozQUcLuM%252C_&biw=1436&bih=805&usg=__CBo6kkqMse2BvZZ-68RBvCt3R5M%3D&ved=0CD0QyjdqFQoTCIuav_Dn1cgCFYNWjgod6ZEH7Q&ei=hrIoVou_CoOtuQTpo57oDg#imgrc=HeO-Y6Rm4CrmzM%3A&usg=__CBo6kkqMse2BvZZ-68RBvCt3R5M%3D/ Tympanic and Lesser petrosal nerve diagram ]
- {{NormanAnatomy|cranialnerves}} ({{NormanAnatomyFig|IX}})
{{Cranial nerves}}
{{Portal bar|Anatomy}}
{{Authority control}}
{{DEFAULTSORT:Tympanic Nerve}}