facial nerve
TRANSCRIPT
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)
Cry
Smile
Salivate
Taste
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
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
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• With branches of V nerve
6. 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 canal2. Nerve to Stapedius3. Chorda tympaniPreganglionic 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
• In the Face (Terminal branches-Pes Anserinus)
1. Temporal
2. Zygomatic
3. Upper & lower Buccal
4. Marginal Mandibular
5. Cervical
Muscles
Of
Face
TemporalZygomatic
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
• Nuclear: Involves VI nerve & Hemiplegia• Infranuclear:1. IAM: Involves VIII nerve2. Facial canal: Dry eyes Hyperacusis Loss of Taste & salivation Muscles of face paralysed
Lower Motor Neuron 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 raisedLesion after nerve comes out of stylomastoid
foramen
BELL’S PALSY
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