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Facial Nerve

Facial Nerve. Dr. Badi ALDOSARI Assistant Professor Facial Plastic Surgery Consultant ENT Consultant King Abdulaziz University Hospital. Facia l Nerve. Embryology Anatomy Physiology Pathology Pathophysiology Evaluation Causes Treatment. Embryology.

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Facial Nerve

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  1. FacialNerve Dr. Badi ALDOSARI Assistant Professor Facial Plastic Surgery Consultant ENT Consultant King Abdulaziz University Hospital

  2. FacialNerve • Embryology • Anatomy • Physiology • Pathology • Pathophysiology • Evaluation • Causes • Treatment

  3. Embryology • The facial nerve is developmentally derived from the hyoid arch , which is the secondbranchialarch • It arises as 2 main divisions- motor and sensory • The motor division of facial nerve is derived from the basal plate of the embryonic pons • The sensory division originates from the cranial neural crest.

  4. FacialNerve • Embryology • Anatomy • Physiology • Pathology • Pathophysiology • Evaluation • Causes • Treatment

  5. FacialNerve • 10,000neurons • 7,000myelinatedfacialexpression. • SuperiorlyalongtheroofoftheIAC(7UP) • Thecourse7segments

  6. FacialNerveAnatomy Facialnervesegments: Pons Cerebulo-pontineangle(CPA) InternalAuditoryCanal(IAC) Labyrinthine Tympanic Mastoid External Fallopiancanal(FC)

  7. Pons 4SsNuclei Solitarius(Taste) Superiorsalivatorynucleus Spinalnucleusofthetrigeminalnerve Seventhmotor

  8. Solitarius

  9. Superiorsalivatorynucleus

  10. Motorpart • Precentralgyrus(frontallobe) • Upperfacecorticobulbarcross • Contralateralpredominance • Motorfiberbendaroundtheabducens(CNVIth)nucleus

  11. Fallopiancanal • Thelabyrinthinesegment • shortest&narrowestpartsusceptibletocompression • Onlysegmentthatlacksarterialanastomosis • embolicphenomena • vascularcompression • Geniculateganglion • 1stgenu(bendorknee) • Commontrunk(nervusintermediusandVIInerve) • Greatersuperficialpetrosalnervelacrimalgland • Tympanicsegment • 50%dehiscent –1st2nd genu

  12. Fallopiancanal • Mastoidsegment –2nd genuverticallystylomastoidforamen • longestpartoftheintratemporalcourse • Branchs • Stapediusmuscle • Chordatympaninerve • submaxillaryandsublingual • Tasteanterior2/3tongue • pain,temperature,andtouchEAC. • Auricularnerve

  13. Extracranial • Postauricularmuscles • Stylohyoidmuscle • Posteriorbellyofthedigastricmuscle • Pesanserinus(goose'sfoot)separatesparotiddeepandsuperficiallobes • 5majorbranchesT,Z,B,M,C • HighestriskduringsurgicalT&M

  14. Pesanserinus(goose'sfoot)

  15. FacialNerve • Embryology • Anatomy • Physiology • Pathology • Pathophysiology • Evaluation • Causes • Treatment

  16. Physiology • Lacrimation • Expression • Mastication • Salivation • Speech • Hearing

  17. FacialNerve • Embryology • Anatomy • Physiology • Pathology • –Pathophysiology • Evaluation • Causes • Treatment

  18. FacialNervePalsy • Degeneration • Metabolicsource(cellbody) • Walleriandegeneration • Beginswithin24hours • Degenerationdistalaxon&myelinsheath • Distaltothesiteofaninjury • WithoutlocalInflammation • Macrophagesdegrademyelinandaxons

  19. FacialNervePalsy • Regeneration • Axonalstumpsswellandproliferatingneurofilaments • Misdirectedregrowthofnervefibers • FacialmusclecontracturesSynkinesia • Salivationcrocodiletears

  20. Pathophysiology • Neuropraxia–noaxonaldiscontinuity • Axonotmesis • Walleriandegeneration(distaltolesion) • Endoneuralsheathsintact • Neurotmesis • Walleriandegeneration(distaltolesion) • Axondisrupted,lossoftubules,supportcellsdestroyed

  21. House-Brackmann • Grade1 • –=Neurapraxia • Spontaneousrecovery • Grade2-3 • –=Axonotmesis • Flowinterruption • Walleriananterogradedegeneration. • Incompletedegeneration

  22. House-Brackmann • Grade4 • –=Neurotmesis(permanentlossofaxons) • Demyelinization • Moderate-to-severefacialmusculaturedysfunction • Regenerativesynkineticmovements • Grade5and6 • Partialorcompletetransectionofthenerve • Minimal/completelossoffunction

  23. FacialNerve • Embryology • Anatomy • Physiology • Pathology • Pathophysiology • –Evaluation • Causes • Treatment

  24. Evaluation • Carefulhistory • Physicalexam • Audiometry • CT/MRI/other • Topographic • Electrophysiology

  25. History • Timing • Associatedsymptoms • SNHL • Vesicles • Severe pain • Trauma • OM acuteor chronic • Pastmedicalhistory

  26. Physicalexam • Complete head and neck exam • Widesmile • Whistling • Blowing • LMNL • Forehead wrinkling • Eyeclosure • Bell’sphenomenon

  27. TopognosticTests • Schirmer’sTest • Stapedialreflex • Taste • SalivaryFlow • Imaging

  28. EvaluationFacialNervePalsy • Electro-Physiology • Electroneurography(ENoG) • Electromyography(EMG) • Nerveexcitabilitytest(NET) • Maximumstimulationtest(MST) ACUTE=Acute+Complete+Unilateral+ThreedaysEvaluate

  29. FacialNerve • Embryology • Anatomy • Physiology • Pathology • Pathophysiology • Evaluation • –Causes • Treatment

  30. FacialNervePalsy • Causes: • Congenital • Trauma • Iatrogenic • Idiopathic • Infection • Toxic • Neurologic • Neoplastic

  31. FacialNervePalsy • Trauma • Forcepsdelivery • Basalskull/temporalbonefractures • Facialinjury • Penetratingtomiddleear • Barotrauma • Lightning

  32. Racooneyessign

  33. Battle’ssign

  34. Fractures • Longitudinal • 80%ofTemporalBoneFractures • 15-20%FacialNerveinvolvement • Transverse • 20%ofTemporalBoneFractures • 50%FacialNerveInvolvement

  35. R

  36. FacialNervePalsy • Iatrogenic • Parotidsurgery • Mastoidsurgery • localanesthesia • Acousticneuroma

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