- Chorda tympani
Nerve: Chorda tympani The right membrana tympani with the hammer and the chorda tympani, viewed from within, from behind, and from above. Gray's subject #231 1047 From facial nerve MeSH Chorda+Tympani+Nerve
The chorda tympani is a nerve that branches from the facial nerve (cranial nerve VII) inside the facial canal, just before the facial nerve exits the skull via the Stylomastoid foramen. It serves the taste buds in the front of the tongue, runs through the middle ear, and carries taste messages to the brain.
The chorda tympani is part of one of three cranial nerves that are involved in taste. The taste system involves a complicated feedback loop, with each nerve acting to inhibit the signals of other nerves. The chorda tympani appears to exert a particularly strong inhibitory influence on other taste nerves, as well as on pain fibers in the tongue. When the chorda tympani is damaged, its inhibitory function is disrupted, leading to less inhibited activity in the other nerves.
The chorda tympani carries two types of nerve fibers from their origin with the facial nerve to the lingual nerve that carries them to their destinations:
- Special sensory fibers providing taste sensation from the anterior two-thirds of the tongue.
- Presynaptic parasympathetic fibers to the submandibular ganglion, providing secretomotor innervation to two salivary glands: the submandibular gland and sublingual gland and to the vessels of the tongue, which when stimulated, cause a dilatation of blood vessels of the tongue.
Enters the skull through the internal acoustic meatus as part of the facial nerve, then it travels through the middle ear, where it runs from posterior to anterior across the tympanic membrane. It passes between the malleus and the incus, on the medial surface of the neck of the malleus.
The nerve continues through the petrotympanic fissure, after which it emerges from the skull into the infratemporal fossa. It soon combines with the larger lingual nerve, a branch of the mandibular nerve
The fibers of the chorda tympani travel with the lingual nerve to the submandibular ganglion.
Special sensory (taste) fibers also extend from the chorda tympani to the anterior 2/3 of the tongue via the lingual nerve.
References and notes
- SUNY Figs 27:03-08
- Cranial Nerves at Yale 7-18
- MedEd at Loyola GrossAnatomy/h_n/cn/cn1/cnb7c.htm
- Chorda+tympani at eMedicine Dictionary
- cranialnerves at The Anatomy Lesson by Wesley Norman (Georgetown University) (VII)
- Photo at Washington University
Nerves of head and neck: the cranial nerves and nuclei (TA A14.2.01, GA 9.855) olfactory (AON->I) optic (LGN->II) oculomotor
trochlear (TN->IV)no significant branches trigeminal
(PSN, TSN, MN, TMN->V)
abducens (AN->VI)no significant branches facial (FMN, SN, SSN->VII)near origininside
(NA, ISN, SN->IX)before jugular fossaafter jugular fossa
(NA, DNVN, SN->X)before jugular fossaafter jugular fossa
accessory (NA, SAN->XI) hypoglossal (HN->XII)
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