trigeminal nerve
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TRIGEMINAL NERVE
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It is V and Largest cranial nerve
Mixed -- Small motor root
Large sensory root
Nerve of the first pharyngeal arch
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Exteroceptive fromSkin of the face & forehead;Mucous membrane of the
nasal cavity;Oral cavity;Nasal sinus;Floor of mouth, teeth;Anterior 2/3 of tongue;Cranial dura
Proprioception from Teeth; Periodontium; Hard palate; TMJ
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Attached to lateral part of ponsSensory root (portio major)Motor root (portio minor)
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Fibers arise from Semilunar
Ganglion
Semilunar ganglion– Develops from neural crest– Crescent shaped– Unipolar neurons– Location- Meckel’s cavity;
superior to petrous part of temporal bone
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Afferent station
Afferent fibers accompany fibers of motor root
Proprioception from TMJ, periodontal membrane, teeth, hard
palate
Afferent impulses from stretch receptors in the muscles of
mastication
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Located at midpontine level
Medial to main sensory nucleus
Fibres distribute to muscles of mastication,
mylohyoid, anterior belly of digastric, tensor
tympani, tensor veli palatini.
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Location – midpons
Forms dorsal trigeminothalamic tract
Ascending fibers terminate in this nucleus
Convey light touch, tactile discrimination,
sense of position and passive movements
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True sensory ganglion
Contains cells that are structurally and
functionally ganglion cells
Convey impulses from the muscles innervated by
the trigeminal nerve and the extraocular muscles,
as well as from the periodontal ligament of the
teeth14
Largest nucleus
Extends caudally from main nucleus to level C3 of
spinal cord
Forms ventral trigeminothalamic tract
Conveys pain and temperature
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extends to the pontomedullaryjunction inferiorly
pontomedullaryjunction to obex
Obex(medulla) to C3 level of spinal cord
Tactile sense Pain and temperature16
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Smallest division
From anterior medial part of semilunar ganglion lateral wall of cavernous sinus
Sensory fibres from Scalp, skin of forehead, upper eyelid lining frontal sinus, conjunctiva of eyeball, lacrimal gland, skin of the lateral angle of eyeball & lining of ethmoid cell 19
Ophthalmic division
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Long ciliary n.Short
ciliary nerves
Infratrochlear
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LACRIMAL NERVE (n. lacrimalis) Smallest branch.
Enters the orbit through the narrowest part of the superior orbital fissure
Runs along the upper part of the lateral rectus
Communicates with zygomatic branch of maxillary nerve.
Enters the lacrimal gland – gives of several filaments
Finally pierces the orbital septum & ends in supplying the skin of upper eyelid.
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Largest branch. Enters the orbit through the superior orbital fissure.
Runs forward between levator palpebrae superioris and periosteum
Divides into two branches in the midway between the apex and base of the orbit
Supratrochlear Supraorbital
FRONTAL NERVE (n. frontalis)
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•Supraorbital Smaller than supratrochlear. Gives filament to join the infratrochlear.
Supplies – Skin over the lower forehead. Conjunctiva Skin of the upper eyelid.
Supratrochlear Passes through the supraorbital foramen. Branches into medial & lateral.
Supplies – Conjunctiva. Skin of the upper eyelid. Twigs to pericranium.
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Nasociliary Nerve (n. nasociliaris)
Intermediate in size and more deeply placed.
Enters the orbit between the two heads of rectus lateralis.
Further passes through anterior ethmoidal foramen.
Supplies internal nasal branches to mucous menbrane.
Emerges as external nasal branch supplying the skin of the ala and apex of the nose.
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SensoryFrom lower eyelid, side of the nose,
upper lip;All maxillary teeth & gingivae, mucous
membrane of most of nasal cavity, hard and soft palate;
Tonsillar region and region of pharynx
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Sphenopalatine ganglion 29
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Zygomaticotemporal:
Exits the zygomatic bone on its medial surface
Pierces the temporal fascia to supply skin over temple
Receives a branch from lacrimal nerve
Communicates with facial nerve and auriculotemporal branch
Zygomaticofacial :
Leaves zygomatic bone on its lateral surface
Supplies skin over malar prominence
Communicate with facial nerve & with inferior palpebral branch of maxillary
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Posterior superior alveolar nerves
• Arise in the pterygopalatine fossa
• Leaves maxillary nerve in pterygopalatine fossa
• Enters the posterior alveolar canals
Branches to
Sinus lining
Three twigs to Molars
Gingiva
Adjoining part cheek
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Middle superior alveolar nerves• Arise from the nerve in the posterior part of the infraorbital canal
• Runs in infraorbital groove on the lateral wall max sinus
• Supply premolars, gingiva & adjoining part cheek
• Forms a superior dental plexus with anterior and posterior superior alveolar branches
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ANTERIOR SUPERIOR ALVEOLAR NERVES• Given off just before exiting from the infraorbital foramen.
• Supplies the incisor and canine teeth.
• Descends in canalis sinosus in anterior wall of maxillary sinus.
• Gives off a nasal branch to supply the mucous membrane of the anterior part of inferior meatus and nasal floor.
• Communicates with the nasal branches of the sphenopalatine ganglion.
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Greater palatine nerveLesser palatine nerve
Pterygopalatine ganglion
INNERVATION OF HARD PALATESensory innervations
Greater palatineNasopalatine
These are branches of maxillary N passing through Pterygopalatine ganglion
Lesser Palatine N ( middle & posterior ) – Uvula, tonsil, soft palate
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GANGLIONS
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Ciliary ganglion • Suspended from nasociliary nerve
• Anatomically belongs to trigeminal nerve
• Functionally belongs to oculomotor nerve
• Carries parasympathetic motor fibres from Edinger – Westphal nucleus
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OTIC GANGLION • Suspended from mandibular nerve
• Anatomically belongs to trigeminal nerve but functionally belongs to glossopharyngeal nerve
• Carries the secretomotor ( nucleus is superior salivary )fibres & distributed via lesser superficial petrosal nerve to Parotid glands.
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Suspended from lingual nerve
Anatomically belongs to trigeminal nerve but functionally belongs to facial nerve
Carries the secretomotor ( nucleus is superior salivary )fibres & distributed via chorda tymoani nerve to submandibular & sublingual salivary glands.
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PTERYGOPALATINE GANGLION • Suspended from maxillary nerve
• Anatomically belongs to trigeminal nerve but functionally belongs to facial nerve
• Carries secretomotor fibres & distributed via the great superficial petrosal nerve ( Nucleus is inferior salivary ) to the Lacrimal glands & the glands of the palate
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Surgical removal of third molars(Von Arx and Simpson, 1989; Rood, 1992)
Osteotomies (Walter and Gregg, 1979; Yoshida et al, 1989)
Trauma (De Man and Bax, 1988)Tooth extractions (Strassburg, 1967; Hansen, 1980)Pulpectomy (Holland, 1994)
Experimental Trigeminal Nerve Injury G.R. Holland CROBM 1996 7: 237
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Implant placementHydroxypatite ridge augmentationEndodontic surgeriesTumour resectionSalivary gland and duct surgeryVestibuloplastyBiopsy procedures
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• Inferior alveolar nerve injury – 0.41-7.5%
• Lingual nerve injury – 0.06-11.5%
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Risk factors for nerve injury
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Local anesthetic toxicity
Formation of epineural hematoma
Needle-barb mechanism of injury
Chemical injury
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Sagittal split osteotomy
Mandibular advancement procedure osteotomies.
Intraoral vertical ramus osteotomy (IVRO)
Genioplasty procedures
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Fracture of mandibular body and ramus
LeFort I & II fractures
Fracture of condylar segment medially
Mandibular angle, body and symphysis fracture
Inadvertent placement of screws
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Overinstrumentation
Chemical injury
Direct trauma from apicoecotomy
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TMJ exposures by preauricular approach
Damage is minimized by incision and dissecting in
close apposition to cartilagenous portion of external
auditory meatus
Fracture of neck of condyle
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Trigeminal neuralgia is defined as sudden, usually unilateral, severe, brief, stabbing, lancinating type of pain in the distribution of one or more branches of 5th cranial nerve
Specific etiology unknown
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Sudden, unilateral, intermittent paroxysmal, sharp, shooting, lancinating, like pain.
Pain is elicited by slight touching superficial ‘Trigger points’
Common triggers include touch, talking, eating, drinking, chewing, tooth brushing, etc.
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MEDICAL TREATMENTDRUGS CURENTLY USED:- 1.Carbamazepine is used as a standard drug , adult dose 200mg TDS & can be increased upto 1600 mg/day in divided doses initially started as small dose & gradually increased to prevent side effects adverse effects include dizziness, ataxia, vertigo, skin rashes . ,etc bone marrow suppression is rare but requires routine . monitoring
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2.Phenytoin sodium usually used in combination of carbamazepine dose 100-400mg/day side effects: gum hyperplasia3. Gabapentin dose is 1200-3600mg/day used with caution in patients with renal & hapatic disease4. Gaba agonist these drugs reduce the central projection of painful impulses eg. Baclofen , adult dose being 10-30 mg TDS
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Surgical treatment• Peripheral nerve block procedure: It involves blocking
of peripheral nerve by long acting LA.
• Alcohol block : 0.5 -2 ml of 95% alcohol can be used for blocking of peripheral nerve.
• Blocking of gasserian ganglion: more effective but it has hazards in sense that alcohol escape into the surrounding subarchanoid space & may cause palsy of adjacent cranial nerve.
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• Post ganglionic sectioning: peripheral neurectomy in which peripheral branch of nerve is avulsed.
• Cryotherapy: peripheral branches are subjected to application of extreme cold by using cryoprobes
In this the nerve is not sectioned but destroyed
• Percutaneous procedure: Percutaneus procedures involes mechanically or chemically damaging parts of trigeminal groove
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• Radiation therapy:
Gamma knife has been used which consists of multiple rays of high energy photon concentrated on trigeminal nerve root.
Can be used to destroy specific components of nerve
Source of radiation is Co 60
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Head neck and brain- bd chaurasiaGray’s anatomyMonheim’s local anesthesia and pain control in
dental practiceHandbook of local anesthesia - malamedPeterson’s principles of oral & maxillofacial surgeryExperimental trigeminal nerve injury g.R. Holland
crobm 1996 7: 237
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