Facial Nerve

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INTRODUCTION VII cranial nerve Nerve of II pharyngeal arch Mixed cranial nerve with sensory & motor components Motor root & sensory root( nervus intermedius/ nerve of Wrisberg)

Taste

Smile

Cry

Salivate

FUNCTIONAL COMPONENTS • Special visceral efferent (BM): Muscles from II pharyngeal arch • General visceral efferent:(Preganglionic parasympathetic fibres): Submandibular, sublingual & lacrimal glands

FUNCTIONAL COMPONENTS • Special visceral Afferent(Taste): Anterior 2/3rds of tongue • General somatic afferent(General sensations): Concha of auricle

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DEEP ORIGIN (NUCLEI) Motor Nucleus (Pons): SVE Superior Salivatory Nucleus (Pons): GVE Lacrimatory Nucleus (Pons) : GVE Nucleus of Tractus Solitarius (Medulla Oblongata): SVA Sensory Nucleus of V Nerve (Pons): GSA

• PONS • MEDULLA OBLONGATA

• FACIAL COLLICULUS Winding of Facial nerve around VI nucleus

CENTRAL CONNECTIONS • The part of motor nucleus supplying upper part of face---controlled by corticonuclear fibres of both sides • The part of motor nucleus supplying lower part of face---controlled by corticonuclear fibres of opposite side (only)

SUPERFICIAL ORIGIN (Attachment to base of Brain) • Lower border of Pons • Between Olive & Inferior cerebellar peduncle • Motor root large, medial to Sensory root • Sensory root between Motor root & VIII nerve

COURSE AND RELATIONS • Passes through Internal Acoustic Meatus • Comes out of Skull through Stylomastoid Foramen • Stylomastoid Foramen divides its course into Intracranial-Intrapetrous part Extracranial part

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INTERNAL ACOUSTIC MEATUS

STYLOMASTOID FORAMEN

Intracranial-Intrapetrous Course: • Internal acoustic meatus • Accompanied by VIII nerve & Labyrinthine vessels • Sensory & motor roots

separate • At bottom of meatus the two roots fuse

Intracranial-Intrapetrous Course: • • • • • • •

Passes above vestibule of internal ear Reaches medial wall of middle ear Bends backwards forming Genu Geniculate ganglion present here Passes above promontory Passes vertically downwards along posterior wall of middle ear Comes out through stylomastoid foramen

Extracranial course: • Passes superficial to styloid process of temporal bone • Enters postero-medial surface of Parotid gland • Superficial to Retromandibular vein & ECA • Divides into Temporofacial & Cervicofacial branches • Form terminal branches • Come out through anterior border of Parotid gland

BRANCHES • Branches of Communication • Branches of Distribution

BRANCHES OF COMMUNICATION 1. In Internal acoustic meatus •

With VIII nerve

2. At Geniculate ganglion • • •

With Pterygopalatine ganglion through Greater superficial petrosal nerve With Otic ganglion by a branch joining lesser petrosal nerve With Sympathetic plexus around Middle meningeal artery through External petrosal nerve

• •

BRANCHES OF COMMUNICATION In Facial canal With auricular branch of Vagus

4. Below Stylomastoid canal •

With IX, X, auriculotemporal, greater auricular nerves

5. In the Face • 6. •

With branches of V nerve

In the Neck With Transverse nerve of neck

BRANCHES OF DISTRIBUTION • In Facial canal 1. Greater superficial petrosal nerve:-joins deep petrosal nerve– Nerve of pterygoid canal– Pterygopalatine ganglion– Postganglionic fibres– Zygomatic nerve– Lacrimal nerve– Lacrimal gland

BRANCHES OF DISTRIBUTION • In Facial canal 2. Nerve to Stapedius 3. Chorda tympani Preganglionic parasympathetic fibres—submandibular ganglion—postganglionic fibres—submandibular gland & through lingual nerve to sublingual gland Taste fibres from anterior 2/3 of Tongue

•

Below Stylomastoid foramen 1. Posterior auricular nerve:Scalp 2. Nerve to Posterior belly of digastric 3. Nerve to Stylohyoid

• 1. 2. 3. 4. 5.

In the Face (Terminal branches-Pes Anserinus) Temporal Muscles Zygomatic Of Upper & lower Buccal Face Marginal Mandibular Cervical

Temporal

Zygomatic

Buccal Marginal mandibular

Cervical

APPLIED ANATOMY Clinical Testing of Facial nerve: Ask patient to • Raise eyebrows • To smile • Close eyes

APPLIED ANATOMY • Supranuclear Palsy • Nuclear & Infranuclear Palsy • Bell’s Palsy

SUPRANUCLEAR PALSY • Upper part of face escapes paralysis coz of bilateral representation of upper part of face in cerebral hemisphere • Lower part of Opposite side of face paralysed

Lower Motor Neuron Palsy • • 1. 2.

Nuclear: Involves VI nerve & Hemiplegia Infranuclear: IAM: Involves VIII nerve Facial canal: Dry eyes Hyperacusis Loss of Taste & salivation Muscles of face paralysed

BELL’S PALSY Muscles of entire half of face paralysed on the side of lesion: • Eyelids cannot be closed-Keratitis, Corneal ulcer • Absence of wrinkles on forehead • Food accumulates in the vestibule of mouth • Nasolabial fold flattened • Angle of mouth cannot be raised Lesion after nerve comes out of stylomastoid foramen

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