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Trigeminal Nerve and Applied Anatomy

  3. INTRODUCTION • The nervous system of man is made up of innumerable neurons which further constitute the nerve fibres • Nerve : A bundle of fibers that uses chemical and electrical signals to transmit sensory and motor information from one body part of the body to another. • Neurons : These are specialized cells that constitute the functional units of the nervous system and has a special property of being able to conduct impulses rapidly from onepart of the body to another.
  4. • The cranial nerves are composed of twelve pairs of nerves that originate from the nervous tissue of the brain. • In order to reach their targets they must ultimately exit/enter the cranium through openings in the skull. • Hence, their name is derived from their association with the cranium.
  5. Nerve in order 1. Cranial Nerve I - Olfactory 2. Cranial Nerve II - Optic 3. Cranial Nerve III - Occulomotor 4. Cranial Nerve IV - Trochlear 5. Cranial Nerve V - Trigeminal 6. Cranial Nerve VI - Abducens 7. Cranial Nerve VII - Facial 8. Cranial Nerve VIII- Vestibulocochlear 9. Cranial Nerve IX - Glossopharyngeal 10.Cranial Nerve X - Vagus 11.Cranial Nerve XI - Spinal Accessory 12.Cranial Nerve XII - Hypoglossal
  6. TRIGEMINAL NERVE DENTIST NERVE • The trigeminal nerve is so called because of its three main divisions i.e. the Ophthalmic, Maxillary & Mandibular nerves. • It is the largest of the cranial nerves. • It is the fifth cranial nerve • It is a mixed nerve : Sensory and Motor • It is sensory to the greater part of the scalp, the teeth, and the oral and nasal cavities. • Motor supply is to the MOM. Proprioceptive nerve fibres arise from the masticatory and extra-ocular muscles.
  7. NUCLEI TRIGEMINAL NUCLEI • A cranial nerve nucleus is a collection of neurons (gray matter) in the brain stem that is associated with one or more cranial nerves. • Axons carrying information to and from the cranial nerves form a synapse first at these nuclei. • Lesions occurring at these nuclei can lead to effects resembling those seen by the severing of nerve(s) they are associated with.
  8. SENSORY NUCLEI : 1.Mesencephalic nucleus : • Cell body of Pseudounipolar neuron • Relay proprioception from muscles of mastication, Extra ocular Muscles, Facial muscles. • Situated in Midbrain just latetral to Aqueduct.
  9. 2.Principal sensory nucleus • Lies in Pons lateral to Motor nucleus • Relays touch sensation
  10. 3.Spinal nucleus • Extends from caudal end of principal sensory Nucleus in pons to 2nd or 3rd spinal segment • It relays Pain and Temperature
  11. MOTOR NUCLEUS : • Innervates muscles of mastication and tensor tympani and tensor palatini • Derived from first branchial arch. • Located in pons medial to principle sensory nucleus.
  12. FUNCTIONAL COMPONENTS Sensory Root Motor Root
  13. SENSORY ROOT • GENERAL SOMATIC AFFERENTS- Face, Scalp, Teeth, Gingiva, Oral, Nasal, Cavities, Para nasal sinus, Conjunctiva and Cornea. Pain, temp, light touch touch, pressure proprioception Trigeminal gang. Bypasses trigem gang. sensory root Spinal nuc. Principal sen nuc. Mesencephalic CNS
  14. MOTOR ROOT CNS MOTOR ROOT MOTOR NUCLEUS MANDIBULAR NERVE Muscles of mastication Tensor tympani Masseter Tensor palatini Lateral & Medial Pterygoids Temporalis
  15. COURSE & DISTRIBUTION • Both motor and sensory root are attached ventrally to junction of pons and middle cerebellar peduncle with motor root lying ventromedially to the sensory root. • Pass anteriorly in middle cranial fossa to lie below tentorium cerebelli in cavum trigeminale, here motor root lies inferior to sensory root.
  16. • Sensory root connected to postromedial concave border of the trigeminal ganglion. • Convex antrolatateral margin of the ganglion gives attachment to the 3 div. of the trigeminal nerve. • Motor root turns further inferior with sensory component of V3 to emerge out of foramen Ovale as Mandibular nerve. • Ophthalmic and Maxillary division emerges through Superior orbital fissure and foramen Rotundum respectively.
  17. GANGLION THE TRIGEMINAL GANGLION • SEMILUNAR OR GASSERIAN GANGLION. • Cresentric in shape with convexity anterolaterally. • 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 lateral to posterior part of lateral wall of the cavernous sinus.
  18. • COVERINGS: covered by dural pouch = MECKLES CAVE or CAVUM TRIGEMINALE cave lined by pia and arachnoid thus the ganglion is bathed in CSF. • ARTERIAL SUPPLY: Ganglionic branches of Internal Carotid Artery, middle meningeal artery and accessory meningeal artery.
  19. RELATIONS • SUPERIORLY: *superior petrosal sinus *free margin of tentorium cerebelli • INFERIORLY: *motor root *greater petrosal nerve *petrous apex *foramen lacerum • MEDIALLY: *posterior part of lateral wall of cavernous sinus *Internal Carotid Artery with its sympathetic plexus • LATERALLY: *uncus of temporal lobe *middle meningeal artery and vein *nervous spinosum
  21. OPTHALMIC NERVE • It is the superior division of the V nerve & is the smallest. • Leaves the cranium and enters the orbit through superior orbital fissure. • It is wholly sensory. • It has 3 branches. All 3 of them pass through the sup. Orbital fissure into the orbit. • They are; 1.Lacrimal nerve 2.Frontal nerve 3.Nasocilliary nerve
  22. 1. Lacrimal nerve: • It is the smallest. • It supplies the lacrimal gland & the conjuntiva. It pireces the orbital septum and ends in the skin of the upper eyelid.
  23. 2) Frontal nerve: • It is the largest branch & appears to be the direct continuation of the ophthalmic division. • It enters the orbit through the SOF divides into 2 branches. i. The supra orbital branch: It is larger & more laterally placed. It supplies the skin of the forehead & scalp as far back as the vertex. It also supplies the mucous membrane of the frontal sinus & pericranium ii. The supra trochlear branch: It is smaller & more medially placed. It curves upward on the forehead , close to the bone. It supplies the skin of the upper eyelid & lower part of theforehead.
  24. 3) Nasocilliary nerve: • It is intermediate in size & runs more deeply. Its branches are divided as following; i. Branches in the Orbit ii. Branches in the Nasal cavity iii. Branches on the face
  25. (I) Branches in the Orbit: i. Long root of the cilliary ganglion: It is sensory & passes through the ganglion without synapsing and supplies the eyeball. ii. Long ciliary nerve: Supplies the Iris & Cornea. iii. Posterior ethmoidal nerve: It enters the post ethmoidal canal & supplies to the mucous membrane lining of the Post. Etmoidal & Sphenoidal paranasal air cells.
  26. iv. Anterior ethmoidal nerve: It supplies to the Ant.ethmoidal & frontal paranasal air cells. In the upper part of the nasal cavity, it further divides into: 1) Internal nasal branches: It has medialseptal branches to the septal membrane. It also has lateral branches, which supply the nasal conchae & the ant. nasal wall 2) External nasal branches: supplies the skin on the tip & ala of the nose.
  27. 2) Branches in the nasal cavity: The branches arising here supply the mucous membrane of the nasal cavity. 3) Terminal branches on the face: They supply sensory nerves to the skin of the medial parts of the both eyelids, the lacrimal sac. They also supply skin on the bridge of the nose.
  28. MAXILLARY NERVE • This is the second & intermediate division of the trigeminal nerve. • It is wholly sensory. • Course: It begins at the middle of the trigeminal ganglion as a flattened, plexiform band, passes horizontally forwards along the lateral wall of the cavernous sinus. It leaves the skull through the foramen rotundum & becomes more cylindrical & firmer in texture.It crosses the upper part of the pterygopalatine fossa, inclines laterally on the posterior part of the orbital process of the maxilla & enters the orbit through the inferior orbital fissure.It is now termed as the infra orbital nerve. It passes through the infra orbital groove & canal in the floor of the orbit & appears on the face through the infra orbital foramen.
  29. • The branches of the maxillary nerve can be divided into the following 4 groups: 1) In the cranium: Meningeal 2) In the pterygopalatine fossa: Ganglionic, Zygomatic, Post.superior alveolar 3) In the infra orbital canal: Middle sup. alveolar, Anterior superior/ Greater alveolar 4) On the face: Palpebral, nasal, superior labial
  30. I. Branch given off on the cranium 1. Meningeal branch: It is given off near the foramen rotundum. It supplies the duramater of the anterior & middle cranial fossae.
  31. II. Branches in the pterygopalatine fossa. 1. The ganglionic branches: They connect the maxillary nerve to the pterygopalatine ganglion.They contain secretomotor fibres to the lacrimal gland. They provide sensory fibres to the orbital periosteum & mucous membrane of the nose, palate & pharynx. 2. The zygomatic nerve: It arises in the pterygopalatine fosssa from the maxillary nerve and travels anteriorly , entering through the inferior orbital fissure where it divides into 2 branches. The Zygomaticofacial nerve perforates the facial surfaces & supplies the skin over the zygomatic bone..
  32. • The Zygomaticotemporal nerve perforates the temporal surface of the zygomatic bone , pierces the temporalis fascia, & supplies the skin over the anterior temporal fossa region. 3. Posterior superior alveolar nerve: • It begins in the pterygopalatine fossa but divides into 3 branches which emerge through the pterygomaxillary fissure. • 2 branches enter the posterior wall of the maxilla above the tuberosity & supply the 3 molar teeth(except the mesiobuccal root of first molar). • The third branch pierces the buccinator & supplies the adjoining part of the gingiva & cheek along the buccal side of the upper molar teeth.
  33. The branches of the Pterygopalatine ganglion are: I. Orbital branches: periosteum of the orbit.Posterior ethmoidal & sphenoidal air cells. II. Palatine branches: 1.Anterior/greater palatine : mucosa of the hard palate & palatal gingiva. 2.Middle palatine : mucous membrane of the soft palate 3.Posterior palatine : mucous membrane of the Tonsillar area. III. Nasal branches: 1.Posterior superior lateral : posterior part of the nasal conchae 2.Nasopalatine/Sphenopalatine : mucous membrane of the premaxilla. IV. Pharyngeal branch: mucous membrane of the nasopharynx
  34. III. Branches in the Infraorbital canal ( Infraorbital nerve) 1. Middle superior alveolar nerve: • It arises from the Infra orbital nerve & runs downwards & forwards along the infraorbital groove along the lateral wall of the maxillary sinus. • It divides into branches which supply the maxillary premolars & mesiobuccal root of the first molar teeth. 2. Anterior superior alveolar nerve: • It also arises in the infraorbital canal near the mid point. It runs in the anterior wall of the maxillary antrum. It runs inferiorly & divides into the branches, which supply the canine & incisors. • A nasal branch from this nerve, given off from the superior dental plexus supplies the mucous membrane of the anterior part of the lateral wall & floor of the nasal cavity. It ends in the nasal septum.
  35. • IV. Branches given on the face: 1. The palpebral branches: • They arise deep to the orbicularis oculi & pierce the muscle, supplying the skin over the lower eyelid& lateral angle of the eye along with the Zygomaticofacial & Facial nerves. 2. The nasal branches: • They supply the skin of the nose & tip of the nasal septum & join the External nasal branch of the anterior ethmoidal nerve. 3. The superior labial branches: • • These are large & numerous. They supply the skin over the anterior part of the cheek & upper lip including the mucous membrane & labial glands. They are joined by the facial nerve & form the infraorbital plexus.
  36. MANDIBULAR NERVE • It is the third & largest division of the trigeminal nerve. • It is made up of 2 roots: a large sensory root which proceeds from the lateral part of the trigeminal ganglion & almost immediately emerges out through the foramen ovale & a small motor root which passes below the ganglion, & unites with the sensory root just outside the foramen. • Immediately beyond the junction of the 2 roots, the nerve sends off the meningeal branch & the nerve to the medial pterygoid. Now the main trunk divides into a small anterior & a large posterior trunk. • As it descends from the foramen, the mandibular nerve lies at a distance of 4 cm from the surface & a little in front of the neck of the mandible.
  37. The braches of the Mandibular nerve: I. Branches of the undivided nerve. i. Meningeal branch/nervus spinosus. ii. Nerve to the medial pterygoid II. Branches of the divided nerve: (A) Anterior division: (B) Posterior division: 1.Buccal nerve 1. Auriculotemporal nerve 2.Massetric nerve 2.Lingual nerve 3.Deep temporal nerve 3.Inferior alveolar nerve 4.Nerve to the lateral pterygoid
  38. BRANCHES OF THE UNDIVIDED NERVE 1.Meningeal nerve: • It enters the skull through the foramen spinosum along with MMA. • It has anterior & posterior divisions that supply the dura of the middle & anterior cranial fossae. 2. Nerve to the medial pterygoid: • It is a slender branch that supplies to the deep surface of the muscle. • It also gives 1-2 filaments to the tensor tympani & the tensor veli palati muscles.
  39. • BRANCHES OF THE DIVIDED NERVE I. Anterior division 1.The buccal nerve: • It passes between the 2 heads of the lateral pterygoid & descends beneath or through the temporalis. It emerges from under cover of the ramus & ant. border of the masseter & unites with the buccal branches of he facial nerve. • It supplies the skin over the ant. part of the buccinator & mucous membrane lining the buccal surface of the gum.
  40. 2.The massetric nerve: • Passes laterally above the lateral pterygoid in front of the TMJ & behind the tendon of temporalis. • It passes through the mandibular notch to sink into the masseter muscle. • It also gives a branch to the TMJ. 3.The deep temporal nerves: • They are 2 in number. • They pass above the upper head of the lateral pterygoid, turn above the infra temporal crest & sink into the deep part of the temporalis muscle. 4.The nerve to the lateral pterygoid • These are 2 in number; one supplying each muscle head.
  41. II.Posterior Division 1.The Auriculotemporal nerve: Course of the nerve • The auriculotemporal nerve arises by a medial & lateral roots, that enclircle the MMA & unite behind it just below the foramen spinosum. • The united nerve passes backwards, deep to the lateral pterygoid muscle & passes between the sphenomandibular ligament & the neck of the condyle. • It then passes laterally behind the TMJ i.r.t. to the upper part of the parotid. It emerges from behind the TMJ, ascends posterior to the superficial temporal vessels & crosses the posterior root of the zygomatic arch.
  42. Branches of the Auriculotemporal nerve: 1. Parotid branches: secretomotor, vasomotor. 2. Articular branches: to the TMJ. 3. Auricular branches: to the skin of the helix & tragus. 4. Meatal branches: Meatus of the tymphanic membrane 5. Terminal branches: Scalp over the temporal region
  43. Lingual nerve • It lies between the ramus of the mandible & the muscle in the pterygomandibular space. • It then passes deep to reach the side of the tongue. Here it lies in the lateral lingual sulcus against the deep surface of the mandible on the medial side of the roots of the third molar tooth where it is covered only by mucous membrane of the gum. • From here it passes on to the side of tongue where it is crosses the styloglossus & runs on the lateral surface of the hyoglossus & deep to the mylohyoid in close relation to the deep part of the submandibular gland &its duct. • It gives off sensory fibres to the tonsil & the mucous membrane of the posterior part of the oral cavity.
  44. Branches of lingual nerve and its communications: 1.Chorda tympani 2.Communications with submandibular ganglion 3.Hypoglossal nerve
  45. Inferior alveolar nerve • It is the largest terminal branch of the posterior division of the mandibular nerve. • The nerve descends deep to the lateral pterygoid muscle at the lower border of the muscle, it passes b/n the sphenomandibular ligament & the ramus to enter the mandibular foramen. • In the canal the nerve runs alongside the inferior alveolar artery as far as the mental foramen where it emerges out& gives off the mental & incisive branches. • From here the nerve runs in the canal giving of branches to the mandibular teeth as apical fibres & enters the apical foramina of the teeth to supply mainly the pulp as well as the periodontium.
  46. Branches of the nerve : 1. Mental nerve: it supplies to the skin of the chin & the mucous membrane as well as the skin of the lower lip. 2. Incisive branch: continues anteriorly from the mental nerve in the body of the mandible to form the incisive plexus & supplies the canine & incisors. 3. Mylohyoid nerve: it is given of before the nerve enters the canal & contains both sensory & motor fibres.It pierces the sphenomandibular ligament, descends in a groove in the medial side of the ramus & passes beneath the mylohyoid line supplying the mylohyoid muscle as well as the anterior belly of the digastric.
  47. Ganglia Associated 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.Submandibular Ganglion: related to lingual n, rests on hypoglossus supplies post gang. Parasym secretomotor fibres to submandibular and sublingual gland.
  48. Examination Of Trigeminal Nerve 1. Sensation Function 2. Motor Function 3. Corneal reflex 4. Test jaw jerk
  49. • Sensation function Use sterile sharp item on forehead, cheek, and jaw If any abnormality present we test the thermal sensation and light touch
  50. • Corneal reflex A clean piece of cotton wool and ask the patient to look away gently touch the cornea with the cotton wool and the patient will blink.
  51. • Test jaw jerk Doctor finger on tip of jaw, grip patellar hammer halfway up shaft and tap finger lightly usually nothing happens, or just a slight closure.
  53. Trigeminal Neuralgia • Also known as Fothergill’s disease,Tic douloureux (painful jerking) • It is defined as , sudden ,usually ,unilateral ,severe ,brief ,stabbing , lancinating , recurring pain in the distribution of one or more branches of trigeminal nerve. • Mean age: 50 y onwards • Female predominance (male : female = 1:2 ~2:3)
  54. Pathogenesis of trigeminal neuralgia: • It is usualy idiopathic. • The probable etiologic factors are: Intra cranial tumors: Traumatic compression of the trigeminal nerve by neoplastic (cerebellopontine angle tumor) or vascular anomalies eg arteriovenous malformations : granulomatous and non granulomatous infections involving 5th cranial nerve.
  55. • Postherpetic Neuralgia • Demyelinating Conditions • Multiple Sclerosis (MS) • Petrous Ridge Compression • Intracranial Vascular Abnormalites
  56. • Pulsation of vessels upon the trigeminal nerve root do not visibly damage the nerve. • However, irritation from repeated pulsations may lead to changes of nerve function, and delivery of abnormal signals to the trigeminal nerve nucleus. • Over time, this is thought to cause hyperactivity of the trigeminal nerve nucleus, resulting in the generation of TN pain.
  57. General characteristics • Incidence: seen in about 4 in 100000 persons • Age of occurrence: 5th to 6th decade • Sex predilection: female predisposition • Side involved more frequently: right side • Division of trigeminal nerve involved; most commonly : max> mand> oph
  58. Clinical characteristics: • Sudden • Unilateral • Intermittent Paroxysmal • Sharp shooting • Lancinating shock like pain elicted by slight touching
  59. • superficial trigger points which radiates across the distribution of one or more branches of the trigeminalnerve • pain rarely crosses the midline • pain is of short duration and last for few seconds to • Minutes • in extreme cases patient has a motionless face called • the frozen or mask like face • presence of intraoral or extraoral trigger points
  60. Provocated by obvious stimuli like • Touching face at particular site • Chewing • Speaking • Brushing • Shaving • Washing the face  The characteristic of the disorder being that the attacks do not occur during sleep.
  61. DIAGNOSIS: • CLINICAL EXAMINATION with HISTORY is mandatory • Response to treatment with tablet of carbamazepine • Injections of local anaesthetic agents into patients trigger zone gives temporarily relief from pain.
  62. TREATMENT: • Medical treatment • Surgical treatment:  Peripheral injections  Peripheral neurectomy  Cryotherapy  Peripheral radiofrequency  Neurolysis(thermocoagulation)  Gasserian ganglion procedures
  63. • Carbamazapine and phenytoin are the traditional anticonvulsants given primarilary • The dosage of the drug used intially should be kept small to minimum especialy in elderly patients to avoid nausea,vomiting and gastric irritation. • Dosage should be taken at night so that adequate serum concentration is present early morning. • Complete blood count,liver function,platelet count should be done prior to treatment. • Onces the pain remission has being achieved the drug dose should be kept at maintainence level or withdrawn and restarted if symptoms reappear • When carbamazepine is contraindicated clonazepam can be given • Co-administration of phenytion or baclofen is also advocated.
  64. THE ALCOHOLIC INJECTIONS: • 95% ABSOLUTE alcohol in small quantites 0.5 to 2 ml is given in peripheral branches of trigeminal nerve. Side effect: Repeated injections may cause • Local tissue toxicity • Inflammation • Fibrosis • Burning alcohol neuritis
  65. Peripheral neurectomy (nerve avulsion): • Oldest and the most effective procedure • Simple • Relatively reliable • Indicated in patients in whom craniotomy is contraindicated due to age,debility,limited life expectancy • Acts by interrupting the flow of a significant number of afferent impulses to central trigeminal apparatus. • Performed mostly on infraorbital,inferior alveolar,mental and rarely lingual nerve.
  66. CRYOTHERAPY FOR PERIPHERAL NERVE: • Direct application of cryotherapy probe (nitrous oxide probe) • Temperature colder than -60 degree C,for 2-3 minutes • Reapeated three times • Produces WALLERIAN degeneration without destroying the nerve sheath
  67. PERIPHERAL RADIOFREQUENCY NEUROLYSIS THERMOCOAGULATION: • Radiofrequency electrode that has the capacity to destroy the pain fibres is used in this procedure. • Temperature being 65 to 75 degree C for 1 to 2 minutes. • Shown to induce pain remissions in 20%of cases.
  68. GASSERIAN GANGLION PROCEDURS: Includes various procedures: 1.Gycerol injection 2.Thermocoagulation 3.Ballon compression
  69. GYCEROL INJECTIONS: • Absolute alcohol or phenol-glycerol mixture can be used as the neurolytic agents. • Agent is injected into meckel’s cave or in the ganglion. • Causes damage to nerve cells presumably through dehydration. • It induces pain relief in 80% of the cases. • Also spares the ophthalmic division and the motor root. .
  70. THERMOCOAGULATION: • A radiofrequency electrode that has the capacity to destroy pain fibres is used. • Alternating currents of high frequency is passed through the electrode. • It produces ionization in the biological tissues leads to coagulation of tissues.
  71. BALLON COMPRESSION: • A Fogarty catheter 1 to 2cm is advanced within the meckels cave through foramen ovale. • Inflated upto 0.75ml at the ventral aspect of theganglion root for 1 minute. • It destroyes the root fibres.
  72. HERPES ZOSTER OPHTHALMICUS • Caused by Varicella zoster • Predilection for nasociliary branch of ophthalmic division of the trigeminal nerve CLINICAL FEATURES: Cutaneous lesions: • Rash • Vesicle • Pustule crust permanent scar
  73. Ocular lesions: • Eyelid: Perorbital pain • Oedema • Hyperasthesia • Conjunctivitis • Scleritis • Corneal scarring • Glaucoma
  74. TREATMENT: • Acyclovir 800mg 5 times /day within 4 days of onset of rash • Analgesics • Antibiotic ointments • Systemic steroids 60mg/day • Corneal grafting
  75. Cavernous Sinus Syndrome • Multiple cranial neuropathies • Exophthalmos, ocular motor defects, 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
  76. Conclusion • Since Trigeminal nerve is mixed nerve, suplies mainly head and neck region. Hence as a dental specialist one should know throughly about itracranial and extracranial course and distribution of Trigeminal nerve,to diagnose the pathologies associated with Trigeminal nerve and for appropriate treatment.
  77. REFERENCES • Anatomy head and neck ( B.D Chaurasia) • Gray’s Anatomy • Anatomy of cranial Nerves • Anatomy for dental Students( A.S. Moni) • Handbook of local anaesthesia by stanley malamed • Textbook of oral and maxillofacial surgery(Neelima Anil Malik) • Harrisson text of internal medicine • Wikipedia