THE TRIGEMINAL NERVE

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THE TRIGEMINAL NERVE : 

THE TRIGEMINAL NERVE Dr. Padmaja Phade

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The largest cranial nerve The part of parasympathetic craniosacral outflow It is mixed nerve ( sensory and motor ) Contains 170,000 sensory fibres 7,700 motor fibres The 3 divisions have approx ophthalmic 26,000 maxillary 50,000 mandibular 78,000

TRIGEMINAL NUCLEI : 

TRIGEMINAL NUCLEI SENSORY NUCLEI : Mesencephalic nucleus - first order sensory nucleus . cell body of pseudounipolar neurons exception to a general rule that first order neuron of CN lie outside CNS. relay proprioception from muscles of mastication, EOM, facial muscles. forms monosynaptic reflex arc . situated in midbrain just lat to aqueduct. Principal sensory nucleus- lies in pons lat to motor nucleus relays discriminitive touch

Conti………. : 

Conti………. Spinal nucleus- extends from caudal end of principal sen. Nuc. In pons to 2nd or 3rd spinal seg where its conti with sub.Gelatinosa. divided in : PARS ORALIS PARS INTERPOLARIS PARS CAUDALIS topographical localization of fibres : V1 – dorsal and caudal part C1 C2 V2- middle part V3- cranial and ventral part in medulla. MOTOR NUCLEUS : innervates muscles of mastication and tensor tympani and tensor palatini derived from first branchial arch. located in pons med. to princi sen. Nuc.

FUNCTIONAL COMPONENTS : 

FUNCTIONAL COMPONENTS SENSORY ROOT GENERAL SOMATIC AFFERENTS FACE, SCALP, TEETH, GINGIVA, ORAL, NASAL ,CAVITIES, PNS ,CONJUNCTIVA, AND CORNEA. Pain,temp,light touch touch, pressure proprioception trigeminal gang. Bypasses trigem gang. sensory root. descending fibres ascending fibres

Conti….. : 

Conti….. descending fibres ascending fibres Spinal nuc. Principal sen nuc. Mesencephalic trigeminal leminiscus (after crossing over and uncrossed dorsal trigeminothalamic tract VPM nuc. Thalamus IC post central gyrus cerebral cortex (areas 3,2,1.)

MOTOR NUCLEUS MOTOR ROOT MANDIBULAR NERVE muscles of mastication tensor tympani massetor tensor palatini lat med pterygoids temporalis

COURSE AND DISTRIBUTION : 

COURSE AND DISTRIBUTION BOTH MOTOR AND SENSORY ROOT ARE ATTACHED VENTRALLY TO JUNCTION OP PONS AND MIDDLE CEREBELLAR PEDUNLE WITH MOTOR ROOT LYING VENTROMED TO THE SENSORY ROOT. PASS ANT IN MIDDLE CRANIAL FOSSA TO LIE BELOW TENTORIUM CEREBELLI IN CAVUM TRIGEMINALE HERE MOTOR ROOT LIES INF TO SENSORY ROOT. SENSORY ROOT CONNECTED TO POSTOMEDIAL CONCAVE BORDER OF THE TRIGEMINAL GANGLION. CONVEX ANT LAT MARGIN OF THE GANGLION GIVES ATTACHMENT TO THE 3 DIV. OF THE TIGEMINAL NERVE. MOTOR ROOT TURNS FURTHER INF. WITH SEN. COMPONENT OF V3 TO EMERGE OUT OF FORAMEN OVALE AS MANDIBULAR NERVE . OPHTHALMIC AND MAXILLARY DIV. EMERGE THROUGH SUP. ORBITAL FISSURE AND FORAMEN ROTUNDUM RESP.

THE TRIGEMINAL GANGLION : 

THE TRIGEMINAL GANGLION SEMILUNAR OR GASSERIAN GANGLION. Sensory ganglion corresponding to DRG of spinal nerves. Cresentric in shape with convexity anterolat. Contains cell bodies of pseudounipolar neurons. LOCATION: lies in a bony fossa at apex of the petrous temporal bone on floor of middle cranial fossa , just lat to post. Part of lat wall of the cavernous sinus. 5 cm deep to the preauricular point.

Conti… : 

Conti… COVERINGS: covered by dural pouch = MECKLES CAVE OR CAVUM TRIGEMINALE. Roof- 2 layers of dura floor- 1 dural and 1endosteal dural layer. cave lined by pia and arachnoid thus the ganglion is bathed in CSF. ARTERIAL SUPPLY: ganglionic branches of ICA, middle meningeal artery and accessory meningeal artery.

Conti… : 

Conti… RELATIONS: SUPERIORLY: sup petrosal sinus free margin of tentorium cerebelli INFERIORLY: motor root greater petrosal nerve petrous apex foramen lacerum MEDIALLY: post. Part of lat. Wall of cavernous sinus ICA with its sympathetic plexus LATERALLY: uncus of temporal lobe middle meningeal BV nervous spinosum.

DIVISIONS OF TRIGEMINAL NERVE : 

DIVISIONS OF TRIGEMINAL NERVE Three divisions 1. ophthalmic nerve 2. maxillary nerve 3. mandibular nerve

OPHTHALMIC NERVE : 

OPHTHALMIC NERVE Smallest div. Only sensory Supplies : cornea,conjuctiva,upper lid,forehead,ant part of scalp,nose. Course: emerges from trigeminal ganglion lat wall cavernous sinus 3 branches in ant part of cavernous sinus lacrimal, nasocilliary, frontal. superior orbital fissure orbit

LACRIMAL NERVE : 

LACRIMAL NERVE Smallest Passes into orbit through lat compartment of the sup orbital fissure outside the tendinous ring. Receives communicating branch from trochlear nerve Receives branch from zygomaticotemporal nerve Passes along sup border of LR with lacrimal art Sensory to lat conjunctiva,UL, lacrimal gland(parasym secretomotor).

FRONTAL NERVE : 

FRONTAL NERVE Largest Enters through lat part of sup orbital fissure outside tendinous ring Passes forward between roof of orbit and LPS Divides midway into SUPRATROCHLEAR NERVE SUPRAORBITAL NERVE

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SUPRATROCHLEAR N SUPRAORBITAL N Smaller nerve Medial Receives commu branch from infratrochlear n Curves around sup med margin of orbit supplies: med conjunctiva and UL lower part of forehead Lies betwn frontalis and corrugator supercilli Larger Lies lateral Passes through supraorbital notch Lies beneath frontalis Divides in med and lat branches. Supplies: conjunctiva, scalp upto vertex, mucous membrane of frontal sinus

NASOCILLIARY NERVE : 

NASOCILLIARY NERVE Sensory only Passes through med part of sup. Orbital fissure within the tendenious ring betwn the two div of occulomotor nerve. Crosses from lat to med above ON with ophthalmic art Runs along med wall of orbit betwn SO and MR Divides into terminal branches ANT ETHMOIDAL NERVE and INFRATROCHLEAR NERVE 5 branches in orbit.

conti : 

conti Communicating branch to cilliary ganglion: passes along short cilliary nerves. carries symp fibres from IC plexus and sensory fibres from the eyeball. LONG CILLIARY NERVES : 2 or 3. run along med side of the ON pierce sclera and supply cornea, iris, cilliary body. carry pain temp and touch. sympathetic motor supply to dilator pupillae. 3. POST ETHMOIDAL NERVE: passes thru post ethmoidal foramen to supply the ethmoid and sphenoid PNS.

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4. INFRATROCHLEAR NERVE: smaller terminal branch emerges below trochlea appears on face above med angle the eye. supplies: upper half of external nose skin of med most part of UL andLL medial conjunctiva lacrimal sac caruncle

l : 

l 5. ANT ETHMOIDAL NERVE: largar terminal branch course: ant ethmoidal foramen and canal into ant cranial fossa on sup surf of cribriform plate Through slit lat to crista galli into nasal cavity Med internal nasal branch lat internal nasal branch Supplies ant nasal septum supplies ant part lat nasal cavity emerges as external nasal nerve to skin of ala,vestibule,and tip of nose

MAXILLARY NERVE : 

MAXILLARY NERVE Second division of trigeminal nerve Pure sensory Supplies derivatives of maxillary process and frontonasal process Course: trigeminal gang. Middle cranial fossa lat wall of cavernous sinus foramen rotundum pterigopalatine fossa in groove on post surf of maxilla through inf orbital fissure into orbit as INFRA ORBITAL N through infraorbital foramen on face

BRANCHES : 

BRANCHES IN MIDDLE CRANIAL FOSSA: meningeal branch IN PTERIGOPALATINE FOSSA: ganglionic branches- related to pterigopalatine ganglion Carry sensations from orbital periosteum,m nose, pharynx,palate Carry post ganglionic parasymp. Secretomotor fibres to lacrimal gland 2.post. Superior alveolar nerve-forms superior dental plexus to supply mm of maxillary sinus and molars.

3.Zygomatic nerve : enters orbit through inf orbital fissure : 

3.Zygomatic nerve : enters orbit through inf orbital fissure A. zygomaticofacial nerve Appears on face thru foramen in the zygomatic bone Supplies skin on prominence of cheek B. zygomaticotemporal nerve Runs along inf,lat orbital wall Appears in infratemporal region thru foramen in zygomatic bone Supplies skin of temporal region after peircing temporal fascia 2 cm above zygoma Gives communicating branch to lacrimal N suppling parasymp. Secretomotor fibres to lacrimal gland.

IN THE INFRAORBITAL CANAL : 

IN THE INFRAORBITAL CANAL 1.middle superior alveolar nerve: runs along lat wall of maxilla Participates in superor dental plexus Supplies premolars. 2. Anterior superior alveolar nerve: Runs in canal in ant wall of maxilla=canalii sinosus #Dental branches # nasal branches Joins sup dental plexus lat wallof inf meatus to to supply canines opening of max sinus.

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3. FACIAL BRANCHES: 1.palpebral nerves-peirces orbicularis occuli and supplies skin of lower lid. 2.nasal branches-supplies skin of lat wall nose and mobile part of septum. 3. superior labial nerve-forms infraorbital plexus supplies skin and mm of upper lip,cheek and labial glands.

MANDIBULAR NERVE : 

MANDIBULAR NERVE Largest Mixed Nerve of 1st branchial arch Motor root- from motor sensory root- gasserian ganglion nucleus in pons exit through foramen ovale in grt. Wing of shenoid from trunk in infratemporal fossa travels between lat. Pterygoid and otic ganglion laterally and tensor palatine medially anteriorly to med. Meningeal A. small ant. Division large post. division

Branches : 

Branches Trunk Nervous spinosus N. to med. Pterygoid Ant. Division Massetric N. Deep temporal N. N. to lat. Pterygoid Buccal N. Post. Division Auriculo temporal Inf. Alveolar Lingual N.

Branches from trunk : 

Branches from trunk Nervous spinosus Through foramen spinosus Dura mid cranial fossa Nerve to med. Pterygoid Supplies medial pterygoid Through otic ganglion without interruption to Tensor tympani Tensor palatini

Branches from the anterior division : 

Branches from the anterior division Nerve to lat pterygoid Massetric nerve- lies sup to lat pterygoid,inf to temporalis tendon and ant to TMJ. supplies masseter and TMJ Buccal nerve-is the only sensory branch of ant div. travels betwn 2 heads of lat pterygoidand emerges in cheek at ant border of masseter. Supplies skin and mm of cheek. Deep temporal nerve-the 2 nerves ascend deep to lat pterygoid and supply temporalis.

Branches from the posterior division : 

Branches from the posterior division 1.Auriculotemporal nerve- Arises from 2 roots which encircle the middle meningeal art The trunk passes post to lat pterygoid betwn neck of mandible and sphenomandibular lig sup to 1st part of maxillary art. Lies behind the TMJ close to the parotid Ascends behind sup temporal vessels and then in temporal region divides into superficial temporal branches.

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Branches of auriculotemporal nerve auricular branches-supply tragus,upper part of aurical,roof of ext auditory meatus,anterosup part of tympanic memb Superficial temporal branches-supply skin of temple Articular branches-supply the TMJ.

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2. Inferior alveolar nerve: Is mixed nerve Passes betwn mandible and sphenomandibular lig inf to lat pterygoid, Enters mandible through mandibular foramen to run in a bony canal below the teeth Branches: to molars and premolars incisive nerve mental nerve mylohyoid nerve-mylohyoid and ant belly of diagastric communicating nerve to lingual nerve

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3.Lingual nerve: lies ant to inf alveolar n betwn lat pterygoid and tensor palatini receives chorda tympani (SVA) Emerges from inf border of lat pterygoid to lie betwn ramus and med pterygoid Betwn origins of sup constrictir and mylohyoid 1 cm below and behind 3rd molar in gingiva Rests on hypoglossus lat to the tongue where it is related to the submandibular ganglion Gives sensory supply to presulcal tongue ,floor of mouth, mandibular gums,and carries proprioception from tongue.

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Branches of lingual nerve and its communications: 1.Chorda tympani 2.Communications with submandibular ganglion 3.Hypoglossal nerve

GANGLIA ASSO WITH THE TRIGEMINAL NERVE : 

GANGLIA ASSO WITH THE TRIGEMINAL NERVE 1.CILLIARY GANGLION: connected with nasocilliary nerve by ganglionic branches in orbit, non synapsing sensory for orbit 2.PTERYGOPALATINE GANGLION: connected to maxillary nerve in infratemporal fossa sensory to orbital septum, orbicularis and nasal cavity ,max sinus , palate , nasopharynx. 3. OTIC GANGLION: betwn trunk of mandibular n and tensor palatini , nerve to med pterygoid passes thru but does not synapse in the ganglion. 4.SUBMSNDIBULAR GANGLION: related to lingual n,rest on hypoglossus supplies post gang. Parasym secretomotor fibres to submandibular and sublingual gland.

CUTANEOUS DISTRIBUTION OF TRIGEMINAL NERVE : 

CUTANEOUS DISTRIBUTION OF TRIGEMINAL NERVE Each half of face is supplied by 13 cut N 1motor and 12 sensory Of 12 sensory : 11 are from trigeminal N 1 is c2 greater auricular N Branches of trigeminal N 5 from ophthalmic:lacrimal supraorbital supratrocheal infratrochlear external nasal

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3 from maxillary N: infra orbital N zygomaticofacial N zygomaticotemporal N 3 from mandibular N: buccal N auriculotemporal N mental N DIVISIONAL SUPPLY: From lat canthus to vertex- ophthalmic N From angle of mouth to vertex- mandibular N Between the two areas-maxillary N

Applied anatomy : 

Applied anatomy TRIGEMINAL NEURALGIA – TIC DOULOUREUX relatively common paroxyms of sudden onset intractable facial pain inv. One or more areas of dist. Of the trigeminal N maxillary and mandibular div commonly inv remissions and exacerbations trigger zone local lesions- ophthalmic div: acute glaucoma frontal sinusitis maxillary div: caries ca maxilla and empyma mandibular div: caries ca tongue or ulcer

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Treatment- Medical: carbamazepine,phenytoin, valproate,pregabalin Thermocoagulation Radiofrequency thermal rhizotomy Alcohol or phenol ablation Microvascular decompression of the nerve at pons Surgical section of the inferolat part of sensory root Elective section of spinal tract of trigeminal N 95% get short term relief with 1/3 relapsing long term

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2. Trigeminal neuropathy sensory loss of face or weakness of the jaw muscles causes- SLE,sjogren syndrome and SS herpes zoster, leprosy meningioma,schwanomma 3.Wallenberg syndrome PICA or vertebral art occlusion infarction of lat medulla IL facial sensory loss, IL horners,IL IX,X,XI palsy IL cerebellar ataxia , CL sensory loss

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4. Herpes zoster ophthalmicus: Recurrent neurocutaneous inf. In opth. Div. of trigeminal dermatome, most freq. affecting nasociliary branch HHV3 / vericella zoster Gasserian ganglion ophthalmic nerve Supraorbital N. Infraorbital N. Supratrochlear N. Infratrochlear N. Nasal N.

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70% of HZ have HZO and 50 to 70% of them suffer from visual morbidity Triggers DM TB AIDS Syphilis Radiation Steroids Physical trauma Pain precedes skin lesion C/P is hemifacial unioccular Cutaneous lesions evolve over few days

Cont…. : 

Cont…. Cutaneous lesion MP rash Vesicle Pustules Crust Permanent scar Ocular complications arises as eruptions subsides Involves mostly nasocilliary branch of ophthalmic N. Ocular complications- Eye lid- periorbital pain, oedema, hyperasthesia, cicatricial entropion, ectropion, trichiasis, maderosis Conjunctiva- conjunctivitis leads to cicatricial symblepheron Sclera- episcleritis and scleritis Cornea Epithelial keratitis Numular keratitis Disciform keratitis Limbal vascular keratitis Neurotrophic keratitis

Cont… : 

Cont… Uveitis- chronic, recurrent granulomatous and non granulomatous uveitis Lens- post. Subcaapsular cataract Glaucoma Vitritis and vitreous hemorrhage Retina- ret. Hemr., CRVO, BRVO, RD, acute retinal necrosis, PORN Ischemic optic neuritis, papilitis III, IV, VI th cranial N. palsy Progressive proptosis Post. Herpetic neuralgias

Diagnosis : 

Diagnosis C/F Cytology – lipschutz bodies Tzanck prepration Electron microscopy with monoclonal AB tagging Fluroscent Ab tech. Real time PCR serology

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D/Ds Eryspilas Eczema herpaticum Eczema vaccinatum Enterovirus asso. Exanthum CD Drug erruption Insect bite

Cont…. : 

Cont…. Treatment Acyclovir 800mg 5 times /day within 4 days of onset of rash ( reduce viral shedding, PHN, pain and increase healing by 50%) Analgesics Topical antibiotics and antiviral not indicated but antibiotic oint. To prevent sec. infections during vesicle eruption Dexa 0.1% 4th hrly + acyclovir oint. 5 times/day + steroid oint. HS in scleritis, sclerosing keratitis Systemic steroids 60mg/day Topical cycloplegic Lubricants Neurotrophic keratitis- lubricating Oint., BCL Lateral tarsoraphy in neurotrophic ulcers Penetrating corneal grafting in neglected disciform keratitis and suprakeratitis which produces scaring and lipoidal deposits in cornea PNH- anlgesic, anti depressants, capsasin cream, trigeminal rhizotomy and stellate gang. block

5.Neurotrophic keratitis : 

5.Neurotrophic keratitis Occurs dt partial or complete corneal anaesthesia dt loss of sensory innervation by the trigeminal N. There is impaired response to corneal microtrauma as a result of impaired regeneration and healing of corneal epi. Causes: infections viz HSV, VZV, leprosy traumatic V N injury sx ablation of gasserian ganglion chemical burns topical anaesthatic abuse, betablockrs,NSAIDS refractive Sx contact lens wear systemic: DM,MS, stroke, brainstem haemorrhage, aneurysm congenital

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Symptoms are typically mild Signs diminished corneal sensations MACKIES GRADING I- subtle corneal surface irreg punctate epithelial keratitis II- frank epithelial defect cellular edema ant stromal inflammation descments folds III- stromal melting corneal perforation

treatment : 

treatment Mild punctate keratitis: preservative free lubricants punctal occlusion Epithelial defects: ointment patching cautious use of mid topical steroids Persistant epithelial defects an ulcers: BCL scleral contact lens topical NGF,IGF,collagenase inhibitors conjunctival flaps lat tarsorraphy botox induced protective ptosis

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4. perforations: cyanoacrylate glue lamellar keratoplasty penetrating keratoplasty amniotic membrane graft

Botulinum toxin : 

Botulinum toxin Neurotoxin produced by Cl. Botulinum Seven types: A, B, C1, D, E, F, G Most used type A ( BOTOX,DYSPORT) and type B (MYOBLOC) It is 150 kDA polypeptide chain with H and L components joined by 1 disulphide bond Commercially available as lyophillized powder Shelf life 36 mths at 2to 8 C and 9 mths at room temp Botox is most potent and longer acting NMJ blocker Final conc used is 10 u/ 0.1 ml or 5u/ 0.1 ml 2 to 4 u given at one site at a time so around 40 u botox injected in toto at one sitting Procedure repeated at 3 to 4 monthly interval.

MOA : 

MOA botulinum toxin A the heavy chain binds to the receptors on presynaptic N terminal memb Complex internalized by endocytosis Lysosomal cleavage of toxin heavy chain light chain inactivates SNARE prot inhibition of AcH release into NMJ localized muscular paralysis

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C/I : NMJ disease co administration of aminoglycosides allergy to eggs Not recommended in : pregnancy lactation children A/E: diplopia dry eye keratitis epiphora transient increase in IOP flu like synd. , nausea, billiary colic.

uses : 

uses Blepharospasm (BEB)- UL and LL every 3 mthly Neurotrophic keratitis and ulcer- anterior LPS chemodenervation where botox total 40 U injected in LPS to induce protective ptosis Protection in keratoplasty pts Cosmetic uses – to erase 1. glabellar furrows 2. lateral rhytids 3. forehead frown lines Entropion- into nasal and temporal lower lid Acute third N palsy- toxin injected in antagonists. Sixth N palsy Strabismus .

Raeders paratrigeminal syndrome : 

Raeders paratrigeminal syndrome Oculosympathetic paresis with pain dist. Of trigeminal N. Pt. with episodic chronic pain Pain and headache Diagnosis- cocaine test for confirmation Hydroxyaphetamine test for localistion Preganglionic- pupil dilates Post ganglionic- pupil doesnot dilate Neuroimaging Trigeminal hyperasthesia seen in post ganglionic

Cavernous sinus syndrome : 

Cavernous sinus syndrome Cavernous sinus syndrome multiple cranial neuropathies exophthalmos, ocular motor defects,horners syndrome, sensory loss in V1 and / or V2. pupils may be spared or involved. causes: bacterial thrombophlebitis actinomycosis rhinocerebellar mucormycosis aspergillosis tolosa hunt syndrome neoplasms vascular lesions

Gradenigos syndrome : 

Gradenigos syndrome Petrous bone osteitis due to otitis media Characterized by I/L trigeminal N palsy (Va, Vb) retro orbital pain I/L sixth N palsy.

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Refrences: Anatomy of head neck face- Datta Snells anatomy Neuroanatomy by Snell Anatomy of the CNS-Poddar Parsons text book Harrisson text of internal medicine Clinical Ophthalmology –Kanski Anatomy and phisiology of the eye- khurana Yanoff and Durker

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