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Nerve: Cochlear nerve
Image:Gray928.png
Diagrammatic longitudinal section of the cochlea. (Cochlear nerve is in center, shown as striped.)
Image:Gray933.png
Part of the cochlear division of the acoustic nerve, highly magnified.
Latin	n. cochlearis
Gray's	subject #203 906
From	Vestibulocochlear nerve
MeSH	A08.800.800.120.910.120

The Cochlear nerve is one of the two branches of the Vestibulocochlear nerve (the Vestibular nerve is the other.)

The cochlear nerve arises from cells in the spiral ganglion of the cochlea. The peripheral fibers pass on to the hair cells of the cochlea, and the central fibers course through the canal of the modiolus and continue to the internal auditory meatus.

Axons of the cochlear nerve synapse in the cochlear nucleus. Cells in the ventral cochlear nucleus then synapse on cells of the superior olives (superior olivary complex) of the pons on the same side and on the opposite side. These cells compare the timing of impulses from the left and right ears, allowing for auditory localization. Superior olive cells' axons form part of a fibre tract, the lateral lemniscus, and go to the inferior colliculus in the tectum. Cells in the dorsal cochlear nucleus send axons directly via the trapezoid bodies and lateral lemniscus to the inferior colliculus. Dorsal cochlear nucleus cells carry information about the frequency of sounds. Axons of the inferior colliculus synapse on the medial geniculate nucleus of the thalamus on the same side and on the opposite side. Axons of medial geniculate neucleus cells project to the primary auditory cortex, also known as A1.

Some reflex fibers pass on to the motor nuclei of the eye musculature and other motor nerve nuclei of cranial and spinal nerves via the tectospinal and tectobulbar tracts.

[edit] See also

• Cochlear implant

[edit] External links

• Cochlear Structures (Flash animation)
• Penn State
• Illustration
• Illustration
• Gray's

Sensory system - Auditory system - edit

Outer ear: Pinna | Ear canal  Middle ear: Eardrum | Ossicles (Malleus, Incus & Stapes) | Stapedius | Tensor tympani | Eustachian tube Inner ear: Cochlea (Scala vestibuli, Scala media & Scala tympani) | Oval window | Helicotrema | Round window | Basilar membrane | Reissner's membrane | Organ of Corti | Hair cells | Stereocilia Brain: Cochlear nerve VIII → Cochlear nuclei → Superior olivary nuclei → Inferior colliculi → Medial geniculate nuclei → Primary auditory cortex

Cranial nerves

I-IV: olfactory - optic - oculomotor - trochlear V: trigeminal: semilunar ganglion V1: ophthalmic: lacrimal - frontal (supratrochlear, supraorbital) - nasociliary (long root of ciliary, long ciliary, infratrochlear, ethmoidal) - ciliary ganglion - short ciliary V2: maxillary: middle meningeal - in the pterygopalatine fossa (zygomatic, zygomaticotemporal, zygomaticofacial, sphenopalatine, posterior superior alveolar) in the infraorbital canal (middle superior alveolar, anterior superior alveolar) on the face (inferior palpebral, external nasal, superior labial, infraorbital plexus) - pterygopalatine ganglion (deep petrosal, nerve of pterygoid canal) branches of distribution (palatine, nasopalatine, pharyngeal) V3: mandibular: nervus spinosus - internal pterygoid - anterior (masseteric, deep temporal, buccinator, external pterygoid) posterior (auriculotemporal, lingual, inferior alveolar, mylohyoid, mental) - otic ganglion - submandibular ganglion VI: abducent VII: facial: nervus intermedius - geniculate - inside facial canal (great petrosal, nerve to the stapedius, chorda tympani) at exit from stylomastoid foramen (posterior auricular, digastric - stylohyoid) on face (temporal, zygomatic, buccal, mandibular, cervical) VIII: vestibulocochlear: cochlear (striae medullares, lateral lemniscus) - vestibular IX: glossopharyngeal: fasciculus solitarius - nucleus ambiguus - sympathetic efferent fibers - ganglia (superior, petrous) - tympanic X: vagus: ganglia (jugular, nodose) - Alderman's nerve - in the neck (pharyngeal branch, superior laryngeal, recurrent laryngeal) - in the thorax (pulmonary branches, esophageal plexus) - in the abdomen (gastric plexuses, celiac plexus, gastric plexus) XI: accessory XII: hypoglossal