Download MBBS Final Year ENT Facial nerve Notes

• Facial nerve is the nerve of second branchial arch

• It's a mixed nerve, contains motor, sensory & autonomic fibres

• Motor - muscles of facial expression , platysma ,post belly of digastric , stylohyoid

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• Sensory –taste sensation from anterior 2/3^rd of tongue , small area around concha of ear

• Autonomic - lacrimal, sublingual & submaxillary glands

• All four nuclei lie in lower pons

1. Motor nucleus/branchiomotor

2. Superior salivary nucleus

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3. Lacrimatory nucleus

4. Nucleus of tractus solitarius

• Special visceral /branchial efferent muscles

• General visceral efferent salivary glands, palatal, nasal & pharyngeal glands

• General visceral afferent afferent impulse from above glands

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• Special visceral afferent ant 2/3^rd of tongue, soft palate

• General somatic afferent skin of ear

COURSE OF FACIAL NERVE

INTRACRANIAL PART

• Attached to brainstem by two roots motor & sensory(nerve of Wrisberg ) at the lower border of pons medial to eight nerve in the cerebellopontine angle

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• 15 – 17 mm in length

• It reach internal acoustic meatus along with vestibulocochlear nerve

INTRA TEMPORAL PART

• MEATAL SEGMENT(15 – 17 mm)

• LABRYNTHINE SEGMENT( 4 mm)

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• Narrowest segment & thin bony canal

• First genu

• TYMPANIC / HORIZONDAL SEGMENT ( 11 mm)

• From geniculate ganglion to pyramidal eminence

• Above oval window & below lateral semi-circular canal

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• MASTOID/VERTICAL SEGMENT (13 mm)

• Pyramid to stylomastoid foramen

• Second genu lies between mastoid & tympanic segment

EXTRACRANIAL PART

BRANCHES

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• Greater superficial petrosal nerve

• Arises from geniculate ganglion & carries secretomotor fibres to lacrimal gland & gland of nasal mucosa & palate

• Nerve to stapedius

• Arises from second genu & supplies stapedius

• Corda tympani

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• Arises from vertical segment , passes between incus & stapes ,leaves tympanic cavity through petro tympanic fissure, supplies to submandibular , sublingual , brings taste from ant 2/3^rd of tongue

• Communicating branch

• Joins auricular branch of vagus & supplies concha ,outer surface of tympanic membrane, posterior meatus

• Posterior auricular nerve

• Supplies muscles of pinna , occipital belly of occipitofrontalis ,communicates with auricular branch of Vagus

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• Muscular branches

• Stylohyoid ,posterior belly of digastric

• Peripheral branches

• Upper temporofacial

• Lower cervicofacial

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• Peripheral branches (pes anserinus )

• Temporofacial

• Temporal

• Auricularis anterior

• Auricularis superior

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• Frontalis

• Orbicularis oculi

• Corrugator supercilia

• Zygomatic

• Orbicularis oculi

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• Cervicofacial

• Buccal

• Two branches – upper & lower buccal,supplies muscles in vicinity mainly buccinator

• Marginal mandibular

• Muscles of lower lip - orbicularis oris , mentalis ,depressor labi anguli etc

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• Cervical

• Platysma

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