logging in or signing up facial nerve anatomy (2) rajeshkundu7 Download Post to : URL : Related Presentations : Let's Connect Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Copy embed code: Embed: Flash iPad Dynamic Copy Does not support media & animations Automatically changes to Flash or non-Flash embed WordPress Embed Customize Embed URL: Copy Thumbnail: Copy The presentation is successfully added In Your Favorites. Views: 816 Category: Education License: All Rights Reserved Like it (0) Dislike it (0) Added: June 14, 2013 This Presentation is Public Favorites: 0 Presentation Description I THINK IT WILL BE HELPED TO MY JUNIOR Comments Posting comment... Premium member Presentation Transcript ANATOMY OF FACIAL NERVE: ANATOMY OF FACIAL NERVE PRESENTED BY DR RAJESH KUNDU PGT ,ENT,NBMC Introduction : Introduction VII Cr Nerve ; Mixed N 10,000 Motor , Sensory , parasympathetic fibers Motor root – 7000 special visc . eff. Fibers Sensory & Parasymp . – 3000 fibers carried by “ NERVUS INTERMEDIUS ”(N of wrisberg )Facial nerve: types of fibers: Facial nerve: types of fibers Special Visceral Efferent/ Branchial Motor General Visceral Efferent/Parasympathetic General Sensory Afferent/Sensory Special Visceral Afferent/TasteSpecial Visceral Efferent/Branchial Motor : Special Visceral Efferent/ Branchial Motor Premotor cortex motor cortex corticobulbar tract bilateral facial motor nuclei ( pons ) facial muscles Stapedius , stylohyoid , posterior digastric , buccinator General Visceral Efferent/Parasympathetic : General Visceral Efferent/Parasympathetic Superior salivatory nucleus ( pons ) nervus intermedius greater/superficial petrosal nerve facial hiatus/middle cranial fossa joins deep petrosal nerve ( symp fibers from cervical plexus) thru pterygoid canal (as vidian nerve) pterygopalatine fossa spheno / pterygopalatine ganglion postganglionic parasympathetic fibers joins zygomaticotemporal nerve(V2) lacrimal gland & seromucinous glands of nasal and oral cavity Superior salivatory nucleus nervus intermedius chorda joins lingual nerve submandibular ganglion – postganglioic parasympathteic fibers submandibular and sublingual glandsGeneral Sensory Afferent/Sensory : General Sensory Afferent/Sensory Sensation to auricular concha , EAC wall, part of TM, postauricular skin Cell bodies in geniculate ganglionSpecial Visceral Afferent/Taste: Special Visceral Afferent/Taste Postcentral gyrus nucleus solitarius –> tractus solitarius – nervus intermedius geniculate ganglion – chorda tympani joins lingual nerve anterior 2/3 tongue, soft and hard palate Structure of nerve : Structure of nerve From inside out Nerve fibre consists of axon ,myelin sheath,neurilemma & endoneurium A group of nerve fibre is enclosed in a sheath called perineurium to form a fascile The fascicles are bound together by epineuriumComponents of a Nerve : Components of a Nerve Endonerium Surrounds each nerve fiber Provides endoneural tube for regeneration Much poorer prognosis if disrupted Perinerium Surrounds a group of nerve fibers Provides tensile strength Protects nerve from infection Pressure regulation Epinerium Surrounds the entire nerve Provides nutrition to nerve Facial Nerve Nuclei : Facial Nerve Nuclei 3 nuclei Motor nucleus – lower pons below 4 th ventricle Superior salivatory nucleus – dorsal to motor N N of tractus solitarius – medulla oblongataCentral Connections of FN: Central Connections of FN Upper part of Nucleus – B/L supra nuclear innervation Lower part of Nucleus– C/L inn. Imp – function of forehead preserved in supranuclear lesions Course : CourseDIVISIONS OF FACIAL NERVE: DIVISIONS OF FACIAL NERVEIntra cranial portion : Intra cranial portion From brainstem to fundus of IAM length 24mm Facial N crosses CP angle with 8 th CN & NI Devoid of epineurium Thin layer of pia mater Surg imp : Iatrogenic trauma in CP angle tumour surgery Difficult to identify in schwannoma (no connective tissue) Meatal Segment : Meatal Segment Enters in ant sup segment of IAC Length 5 – 12 mm No separate sheath Shares with NI & 8 th CN Bath in CSF Intra Temporal Region : Intra Temporal Region Length – 28 to 30 mm Longest bony canal 3 segments by 2 genus Labyrinthine Segment : Labyrinthine Segment Narrowest(0.68) & Shortest(3-5mm) Meatal foramen No anastomosing arteries Periostium is thicker Posterosuperior to cochlea Anteromedial to SSCC Posterior to vestibule Distal end – Geniculate ganglion;1 st genu Internal auditory canalPowerPoint Presentation: Surgical importance: Anatomical bottle neck – ischemia in oedema Part most vulnerable for ischemia(no arterial anastomosis ) Temporal bone # - MC injured Geniculate ganglion :(distal end) Bipolar ganglion cells Afferent input pain & taste febres Secretomotor fiber to lacrimal gland(without synapse)GSPN Tympanic Segment : Tympanic Segment From Geniculate ganglion to 2 nd genu Length – 8 to 11mm Lies beneath LSCC & above OW At its proximal end,above & medial to “ Processus cochleariformis & TT muscleCont..: Cont.. Creats 2 recesses Facial recess (lat) Sinus tympani(med)Cont..: Cont.. Surgical importance: Processus cochleariformis ( consistant landmark) Imp landmark for 2 nd genu - Hug the inf. LSCC -Pyramidal eminence -B/w short process of incus (L) & LSCC(M) CT SMF Mastoid Mastoid Segment : Mastoid Segment From 2 nd genu (PM) to SMF(AL) Longest (13mm) Landmark – “ Digastric Ridge” identified by medial aspect of mastoid tip FN leaves FC via SMF(b/w mastoid tip & styloid process) Has 3 brances CT N to stapedius sensory auricular branch Extra Temporal Region : Extra Temporal Region From SMF to terminal branches Runs in substance of parotid Main trunk divides - upper temperofacial - lower cervicofacial “ Pes anserinus ” Superficial to Retromandibular V & Ext.carotid art Branches of facial N : Branches of facial N Intra temporal region : GSPN N to stapedius Chorda tympani Sensory auricular branch GSPN: GSPN From Geniculate ganglion 2 types of fibers Preganglionic para sympathetic – Pterygopalatine gang. Postganglionic – lacrimal gland Sensory fibers to nasal & palatine glands Joins deep petrosal N – N to pterygoid canalCONT..: CONT.. N to stapedius 6mm above SMF Supply stapedius Sensory auricular Br Joins auricular br of vagus Supply retro-auricular groove & concha Chorda tympani : Chorda tympani 4mm above SMF Lat & ant to Facial N Passes b/w long process incus & upper part of handle of malleus 2 types of fibers Preganglionic parasympathetic – submandibular Ganglion Postganglionic – submandibular & sublingual gland Special sensory – ant 2/3 rd of tongueCONT..: CONT.. Surgical importance: GSPN - landmark in middle cranial fossa approach CT – landmark in post tympanotomy CT – lat margin of facial recess CT – medial limit for facial ridge in CWDExtratemporal region: Extratemporal region The stylomastoid foramen > medial aspect of mastoid tip > FN exit from SMF>below tympanic plate& L to the base of styloid > nonvascular area Lat to base of cartid sheath & behind the parotid gland. Post.auricular N( occ frontalis &muscles of pinna ) Muscular Brs (post belly of digastric & stylohyoid ) Terminal branches : Terminal branches Terminal branches: Temporal Zygomatic Buccal Mandibular CervicaCont..: Cont..Cont..: Cont.. Temporal : Comes out through the upper pole of parotid gland Cross zygomatic arch Auricularis anterior & superior, frontalis orbicularis oculi & corrugator supercilii Zygomatic : Also called upper zygomatic Cross zygomatic bone Orbicularis oculiCont..: Cont.. Marginal mandibular : Comes out through the ant. Boarder of partid gland Runs 1-2cm below the inferior ramus of mandible Muscles of lower lip&chin ( Deperessor anguli oris ,Depressor labii inferioris,Mentalis ) Cervical : Comes out through the lower pole Supply platysma Buccal : 1 cm below zygomatic arch 2 in number runs along parotid ductCont..: Cont.. Buccal br :1.Upper deep buccal 2.Lower deep buccal Risorius (smirk) Buccinator (aids chewing) [LDB] Levator Labii Superioris Levator Labii Alaque Nasi (snarl) Levator Anguli Oris (soft smile) Nasalis (Flare Nostrils) Orbicularis Oris (Purse Lips)Anatomical Relationship of FN in adult & children : Anatomical Relationship of FN in adult & children Child Adult Absent mastoid process & incomplete tympanic ring .CT may exit thru SMF 2 nd genu is more acute & lateral N trunk on exit from SMF is more anterior & lateral N very superficial over angle of mandible Presnt mastoid process & complete ring .CT exits separately prox to SMF 2 nd genu less acute & more medial Parotid is more post. N trunk is less anterior & deeper N superficial over angle of mandible Blood Supply : Blood Supply AICA > Supply N in CP angle Intracranial/ Meatal : labyrinthine branches from ant inf cerebellar artery Geniculate&Perigeniculate : superficial petrosal branch of middle meningeal artery Tympanic/Mastoid: stylomastoid branch of posterior auricular arteryFacial nerve embryonic development: Facial nerve embryonic development Facial nerve course, branching pattern, and anatomical relationships are established during the first 3 months of prenatal life The nerve is not fully developed until about 4 years of age The first identifiable FN tissue is seen at the third week of gestation- facioacoustic primordium or crestFacial nerve embryology: 4th week : Facial nerve embryology: 4 th week By the end of the 4 th week, the facial and acoustic portions are more distinct The facial portion extends to placode The acoustic portion terminates on otocystFacial nerve embryology: 7th week: Facial nerve embryology: 7 th week Early 7 th week, geniculate ganglion is well-defined and facial nerve roots are recognizable The nervus intermedius arises from the ganglion and passes to brainstem. Motor root fibers pass mainly caudal to ganglionFacial nerve embryology: 7th week: Facial nerve embryology: 7 th weekFacial nerve embryonic development: Extratemporal segment - branches: Facial nerve embryonic development: Extratemporal segment - branches Proximal branches form first 6 th week, posterior auricular branch>branch of digastric Early 8 th week,temporofacial and cervicofacial divisions Late 8 th week, 5 major peripheral subdivisions presentFacial nerve embryonic development: Extratemporal segment – other nerves : Facial nerve embryonic development: Extratemporal segment – other nerves Facial nerve communicates with peripheral branches of CN V, IX, X, cervical cutaneous nerves greater auricular nerve and transverse cervical branches of the cervical plexus (C2, C3) Trigeminal nerve: auriculotemporal , infraorbital , buccal , mental branches All connections are complete by week 12 except for 4 (connections to branches of CN V at orbit periphery)-these are complete at 4.5 monthsPeripheral communications of facial nerve : Peripheral communications of facial nerveFacial nerve embryonic development: Extratemporal segment – Parotid : Facial nerve embryonic development: Extratemporal segment – Parotid Surgical Landmarks : Surgical Landmarks Ear & mastoid surgery Geniculate ganglion lies superior to Processus cochleariformis 2 nd genu hugs inferior aspect of LSCC Facial N lies above OW niche Incus lies lateral to Facial N Facial N runs behind Pyramid Facial N lies 6-8mm inferior to Tympano Mastoid suture Digastric ridge – mastoid segmentCont…: Cont… Parotid surgery Tragal pointer – 1cm deep&inf Tympanomastoid suture N lies lat to Styloid process Superficial to Retromandibular vein N bisects angle b/w Post belly of digastric & ear canal Buccal br I cm below¶llel to zygomatic arch Variations : Variations MC variations Facial N displacements Dehiscence of fallopian canal Dehiscence in tympanic seg (35-55%)-mc Vertical seg variations Bipartite N Ant displaced N With post humpCont..: Cont.. Katz & Catalano classification: Type I (25%)no anastomic links bet the 2 branches Type II (14%) buccal branch subdivided Type III(44%) Type IV(14%) Type V(3%)PowerPoint Presentation: Otology could be a dull way of life without the 7 th cranial N arrogantly swerving through the temporal bone to the muscles of facial expression “JOHN GROVES” THANK YOU You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.