Trigeminal nerve


Published on


  • Be the first to comment

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Trigeminal nerve

  1. 1. Contents:1. Introduction. 2. Structure of a nerve. 3. List of cranial nerves and its classification. 4. Embryology of trigeminal nerve. 5. Nuclei of trigeminal nerve. 6. Trigeminal Ganglion. 7.Course of trigeminal nerve.
  2. 2. 8. Branches. 9.Ganglia associated with trigeminal nerve. 10. Applied anatomy. 11. Conclusion. 12. Bibliography.
  3. 3. 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 one part of the body to another.
  4. 4. Elementary structure of a typical neuron Neuron consists of a cell body also called as soma or perikaryon. I t gives off a variable number of processes called as neurites. They are of two types: -Dendrites -Axon
  5. 5. AXON has following structures from inside to outside: Axon. Myelin sheath. Endoneurium- which is the connective tissue layer. It separates and encircle each nerve fibre. Perineurium- it imparts strength to the nerve as well as resistance to spread of infection. Epineurium- consists of loose areolar connective tissue. Contains lymph vessels and blood vessels.
  6. 6. Basic difference between axon and dendrites AXON  Extend for a considerable distance away from cell body.  Has a uniform diameter  Devoid of nissl gran]ules. DENDRITES  They terminate near the cell body.  Fundamental functional  Nerve impulse travel difference is that the impulse travels away from the cell body.  Irregular in thickness  Nissl granules extend into them. towards the cell body.
  7. 7. The cranial nerves are composed of twelve pairs of nerves that emanate 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.
  8. 8. Nerve in order Cranial Nerve I Cranial Nerve II Cranial Nerve III Cranial Nerve IV Cranial Nerve V Cranial Nerve VI Cranial Nerve VII Cranial Nerve VIIICranial Nerve IX Cranial Nerve X Cranial Nerve XI Cranial Nerve XII - Olfactory Optic Occulomotor Trochlear Trigeminal Abducens Facial Vestibulocochlear Glossopharyngeal Vagus Spinal Accessory Hypoglossal
  9. 9. Classification of cranial nerves Sensory cranial nerves: contain only afferent (sensory) fibers ⅠOlfactory nerve ⅡOptic nerve Ⅷ Vestibulocochlear nerve Motor cranial nerves: contain only efferent (motor) fibers Ⅲ Oculomotor nerve Ⅳ Trochlear nerve ⅥAbducent nerve Ⅺ Accessory nerv Ⅻ Hypoglossal nerve Mixed nerves: contain both sensory and motor fibers ⅤTrigeminal nerve, Ⅶ Facial nerve, ⅨGlossopharyngeal nerve ⅩVagus nerve
  10. 10. EMBRYOLOGY OF THE NERVE During the development of embryo, the pharyngeal arches appear in the fourth and fifth week. It give rise to six pharyngeal arches, of which the 5th arch dissapears.
  11. 11. Each arch is characterized by its own: muscular component  nerve component  arterial component  skeletal component - Trigeminal nerve is derived from 1st pharyngeal arch
  12. 12. Musculature of the first pharyngeal arch includes:Muscles of mastication : Temporalis Masseter Pterygoids Anterior belly of diagtric Mylohyoid Tensor tympani Tensor palatini The nerve supply to these muscles is provided by mandibular division of trigeminal nerve.
  13. 13. Mesenchyme from the 1st arch also contributes to the dermis of the face,hence sensory supply to the skin of the face is provided by ophthalmic, maxillary and mandibular branches of the trigeminal nerve.
  14. 14. Nuclei of trigeminal nerve:It has got 4 nuclei : 1) Main sensory nuclei 2) Spinal nuclei 3) Mesencephalic nuclei 4) Motor nuclei sensory
  15. 15. 1.Mesencephalic nuclues in midbrain. 2.Main sensory nucleus situated in upper pons. 3.Spinal nuclues in upper pons to C2 segment of spinal cord. 4.Motor nucleus situated in upper pons.
  16. 16. SENSORY NUCLEI : 1.Mesencephalic nucleus. Situated in midbrain. First order sensory nucleus. Cell body of pseudounipolar neurons. Recieves general somatic afferent fibres. Relay proprioception from : -muscles of mastication -facial muscles -eye
  17. 17. 2.PRIMARY SENSORY NUCLEUS Situated in upper part of pons lateral to motor nucleus. Recieves general somatic afferent fibres. Relays impulses of touch and pressure from skin and mucous membrane of facial region.
  18. 18. 3.The spinal nucleus: it extends from caudal end of principal sensory nucleus In pons to 2nd or 3rd spinal segment where it continues with sub. Gelatinosa Divided into three parts :1. Subnucleus oralis 2. Subnucleus interpolaris 3. Subnucleus caudalis It receives general somatic afferent fibres Relays the impulses of pain and temperature of face
  19. 19. 4.THE MOTOR NUCLUES :It is situated in upper pons medial to principal sensory nucleus. Contains efferent fibres. Innervates muscles of mastication and tensor tympani and tensor palatini.
  20. 20. The trigeminal nerve nucleus
  21. 21. FUNCTIONAL COMPONENTS SENSORY ROOT GENERAL SOMATIC AFFERENTS FACE, SCALP, TEETH, GINGIVA, ORAL, NASAL ,CAVITIES, PNS ,CONJUNCTIVA, AND CORNEA. Pain,temp,light touch touch, pressure trigeminal gang. proprioception Bypasses trigem gang. sensory root. descending fibres ascending fibres
  22. 22. descending fibres Spinal nuc. ascending fibres Principal sen nuc. Mesencephalic Trigeminal Leminiscus Thalmus Post Central Gyrus Cerebral Cortex (areas 3,2,1.)
  23. 23. THE TRIGEMINAL GANGLION :Also known as Gasserian ganglion, or semilunar ganglion, is a sensory ganglion of the trigeminal nerve that occupies a cavity ( Meckel's cave) in the dura mater, covering the trigeminal impression near the apex of the petrous part of the temporal bone.
  24. 24. It is somewhat crescentic or semilunarin shape, with its convexity directed anteriomedialy. The three divisions of the trigeminal nerve emerges from this convexity.
  25. 25. ASSOCIATED ROOTS AND BRANCHES:The central processes of the ganglion cells form the large sensory root of the trigeminal nerve ,which is attached to pons at its junction with the middle cerebellar peduncle. The peripheral processes form the three divisions of the trigeminal nerve.
  26. 26. The small motor root of the trigeminal nerve is attached to the pons superomedialy to the sensory root. It passes under the ganglion from its medial to the lateral side and joins the mandibular nerve at the foramen ovale.
  27. 27. RELATIONS:MEDIALY- Internal carotid artery posterior part of cavernous sinus LATERALY-Middle meningeal artery SUPERIORLY- Parahippocampal Gyrus INFERIORLY-Motor root of trigeminal nerve greater petrosal nerve apex of the petrous temporalbone foramen lacerum
  28. 28. ARTERIAL SUPPLY:Ganglionic branches of ICA, middle meningeal artery and accessory meningeal artery.
  30. 30. Trigeminal nerve is the largest cranial nerve. It is a mixed nerve. Composed of a small motor root and a considerably larger sensory root. The sensory root contains 170000 fibres and the motor root contains 7700 fibres.
  31. 31. Trigeminal nerve Ophthalmic (sensory) Maxillary (sensory) Mandibular (mixed)
  33. 33. The Ophthalmic division:Superior and smallest division. Wholly sensory. Arises from the anteriomedial end of trigeminal ganglion as a flat band,2’5cm long. Passes forward in the lateral wall of the cavernous sinus, below the oculomotor and trochlear nerves.
  34. 34. Nerve is joined by the filaments from the internal carotid sympathetic plexus. It communicates with the oculomotor,trochlear and abducent nerve. The latter communication may be the route by which proprioceptive fibres from extraocular muscles enter the trigeminal nuclear complex.
  35. 35. Before entering the orbit by the superior orbital fissure it divides into Lacrimal (smallest) Nasociliary (intermediate) Internal nasal Long ciliary External nasal Frontal (largest) Supra Supra Troclear Orbital Infra Posterior Trochlear Ethmoidal
  36. 36. Lacrimal nerve: Smallest of main ophthalmic branches Enters the orbit through the lateral part of the superior orbital fissure Runs along the upper border of the rectus lateralis with the lacrimal artery Receives a twing from the zygomaticotemporal branch of maxillary nerve.which contains lacrimal secretomotor fibres
  37. 37. Supplies the lacrimal gland and the adjoining conjunctiva. Pierces the orbital septum. Ends in the upper eyelid, where it joins filaments of the facial nerve.
  38. 38. FRONTAL NERVE: Largest branch of the ophthalmic division. Enters the orbit by the superior orbital fissure. Divides midway between the apex and the base of the orbit into two branches: Supratrochlear (small) Supra orbital (large)
  39. 39. SUPRATROCHLEAR BRANCH: Runs anteromedially,passing above the troclear. Supplies a descending filament to the infratrochlear branch of naso ciliary nerve. Then it emerges between the trochlea and the supraorbital foramen and supplies - conjunctiva - skin of the upper eyelid - skin of the lower forehead near the midline
  40. 40. THE SUPRAORBITAL BRANCH Proceeds between the levator palpabrae superioris and the orbit al roof Transverses the supraorbital foramen, supplying the upper eyelid and conjunctiva Then ascends on the forehead with the supraorbital artery,dividing into medial and lateral branches,which supply the skin of the scalp till the lambdoid suture The main nerve and both branches also supply the mucosa of the frontal sinus and the pericranium.
  41. 41. NASOCILIARY BRANCH Intermediate in size between frontal and lacrimaL Deeply placed in the orbit Enters the orbit through the annular tendon lying between the two rami of the oculomotor nerve Runs obliquely below the rectus superior to the medial orbital wall Here, as anterior ethmoidal nerve, it transverse the anterior ethmoidal foramen and canals
  42. 42. Enters the cranial cavity from where it descends into nasal cavity through a slit lateral to crista galli, supplies two internal nasal branches At the lower border of the nasal bone it emerges as the external nasal nerve and supplies the skin of the nasal ala, apex and vestibule The nasociliary nerve connects with the ciliary ganglion and has long ciliary, intratrochlear and posterior ethmoidal branches
  43. 43. Two or three long ciliary nerve branch from nasociliary runs forward between sclera and choroid and supply the ciliary body, iris, cornea The infratrochlear branches from nasociliary near the anterior ethmoidal foramen and supplies the skin of the eyelids and the side of the nose, conjunctiva, lacrimal sac and lacrimal caruncle The posterior ethmoidal nerve leaves the orbit by the posterior ethmoidal foramen and supplies the ethmoidal and the sphenoidal sinuses
  44. 44. The Maxillary Nerve: It is intermediate division of trigeminal nerve. Wholly sensory. ORIGIN: It leaves the trigeminal ganglion between the ophthalmic and mandibular divisions as a flat plexiform band Passes slightly medial to lateral wall of cavernous sinus Leaves the cranium through foraman rotandum, which is located in the greater wing of sphenoid bone.
  45. 45. Once outside the cranium, it crosses the uppermost part of the pterygopalatine fossa, between the pterygoid plates of sphenoid bone and the palatine bone As it crosses the pterygopalatine fossa it gives of branches sphenopalatine ganglion zygomatic branches posterior superior alveolar nerve
  46. 46. It then angles laterally in a groove on the posterior surface of the maxilla,entering the orbit through the inferior orbital fissure Within the orbit it occupies the infraorbital groove and becomes the infraorbital nerve,which courses anteriorly into the infraorbital canal The maxillary division emerges on the anterior surface of face through the infraorbital foramen, where it divides into its terminal branches, supplying the skin of the face, nose, lower eyelid and upper lip
  47. 47. Meningeal nerve: Also known as nervus meningeus medius. It lies within the cranium. It receives a ramus from the internal carotid sympathetic plexus and accompanies the middle meningeal artery to supply the duramater.
  48. 48. Branches through pterygopalatine fossa: ZYGOMATIC NERVE:Starts in the pterygopalatine fossa. Enters the orbit through the inferior orbital fissure. Divides into two branches. Zygomaticcotemporal: supplying sensory innervation to skin on the side of the forehead. Zygomaticofacial: supplying the skin on the prominence of the cheek.
  49. 49. Before leaving the orbit the zygomatic nerve communicates with the lacrimal nerve of the ophthamic division which carries secretory fibres from pterygopalatine ganglion to lacrimal gland.
  50. 50. POSTERIOR SUPERIOR ALVEOLAR NERVE: It descends from the main trunk of the maxillary division in the ptergopalatine fossa. Through the pterygopalatine fossa,it reaches the inferior temporal surface of the maxilla. From here it enters maxilla through the psa canal
  51. 51. Travel down the posteriolateral wall of the maxillary sinus. Provides sensory innervation to the mucous membrane of the sinus. Continuing downward it provides sensory innervation to the alveoli,periodontal ligaments,and pulpal tissues of the maxillary 3rd ,2nd and 1st molar. Applied anatomy:-During a nerve block there is great risk of hematoma formation .
  52. 52. The Pterygopalatine Nerve: This nerve turns straight downward after it has left the trunk of the second division The pterygopalatine ganglion is attached to the medial side of the nerve.
  53. 53. Branches of pterygopalatine nerve includes those that supply four areas:orbit nose – a) superior posterior nasal medial lateral b) nasopalatine palate- a) greater (anterior) b)lesser (middle & posterior) pharynx
  54. 54. The orbital branches supply the periosteum of the orbit.
  55. 55. The superior posterior nasal branches are given off at the level of the ganglion. Enter the nasal cavity through the sphenopalatine foramen. Lateral branches of superior posterior nasal nerve supply upper and middle conchae. Medial branches of the nerve pass over the roof of the nasal cavity to the nasal septum,one of the medial branches is distinguished by its great length and by its diagonal course downward and forward along the nasal septum,it is called the nasopalatine nerve. The nasopalatine nerve gives off branches to the anterior part of the nasal septum and the floor of the nose
  56. 56. Enters the incisive canal , passes into oral cavity via the incisive foramen, located in the midline of the palate about 1cm posterior to the maxillary central incisors. The right and left nasopalatine nerves emerge together through this foramen and provide sensation to the palatal mucosa in the region of premaxilla ( canine to central incisor)
  58. 58. GREATER PALATINE NERVE: Emerges on the hard palate through the greater palatine foramen (usually located about 1cm towards the palatal midline, just distal to the second molar) The nerve courses anteriorly supplying sensory innervation to the palatal soft tissues and bone as far as the first premolar, where it communicates with the terminal fibres of the nasopalatine nerve. It provides sensory innervation to some parts of soft palate
  59. 59. The Middle Palatine Nerve: Emerges from the lesser palatine foramen along with the posterior palatine nerve . Provides sensory innervation to the mucous membrane of soft palate The posterior palatine nerve: Innervates the tonsillar region.
  60. 60. THE PHARYNGEAL BRANCH: It is a small nerve Passes through the pharyngeal canal and is distributed to the mucous membrane of the nasal part of the pharynx posterior to the auditory tube.
  61. 61. BRANCHES IN THE INFRAORBITAL CANAL: The nerve enters the orbit through the inferior orbital fissure, and is then called the infra orbital nerve passing through the infra orbital canal. Within the canal it gives of two branches: middle superior alveolar branch anterior superior alveolar branch
  62. 62. THE MIDDLE SUPERIOR ALVEOLAR NERVE (MSA): Arises from the infra orbital nerve. Provides sensory innervation to two maxillary premolars and perhaps to the mesiobuccal root of the first molar and the periodontal tissues, buccal soft tissues and bone in the premolar region. Traditionally it has being stated that the MSA nerve is absent in 30% to 54% of individuals. In its absence the usual innervations are provided by either the PSA or the ASA nerve, most frequently the latter.
  63. 63. The Middle Superior and Anterior Superior Alveolar nerve:
  64. 64. THE ANTERIOR SUPERIOR ALVEOLAR NERVE (ASA): It is a relatively larger branch Given off from the infraorbital nerve at approximately 6 to 10mm before the latter exit from the infraorbital foramen It provides pulpal innervation to the: central and lateral incisors canine periodontal tissues buccal bone mucous membrane of these teeth.
  65. 65. BRANCHES ON THE FACE: The infraorbital emerges through the infraorbital foramen onto the face to divide into its terminal branches: 1) the inferior palpebral:- supplying the skin of the lower eyelid 2) the external nasal branch:- providing sensory innervation to skin of lateral part of the nose 3) the superior labial branch:- supplying the skin and mucous membrane of the upper lip.
  66. 66. THE MANDIBULAR DIVISION: Largest division of trigeminal nerve Mixed in nature Has a large sensory root and a small motor root The sensory root originates from trigeminal ganglion whereas the motor root originates in the pons and medulla ablongata The two roots emerge from the cranium separately through the foramen ovale, the motor root lying medial to sensory they unite just outside the skull and form the main trunk of 3rd division
  67. 67. BRANCHES OF THE MANDDIBULAR NERVE: MANDIBULAR NERVE Undivided nerve Divided nerve Anterior Posterior division division
  68. 68. Undivided Nerve Nervus spinosus Nerve to medial pterygoid muscle
  69. 69. Divided Nerve 1. anterior division- nerve to lateral pterygoid nerve to masseter muscle nerve to temporal muscle buccal nerve 2. posterior division- auriculotemporal nerve lingual nerve mylohyoid nerve inferior alveolar nerve- incisive mental
  70. 70. BRANCHES OF THE UNDIVIDED NERVE: On leaving the foramen ovale the main undivided trunk gives two branches during its 2-3mm course ie the meningeal branch and the nerve to medial pterygoid THE MENINGEAL BRANCH Also called as Nervus Spinosus. It re-enters the cranium through the foramen spinosum along with the middle meningeal artery to supply the duramater.
  71. 71. NERVE TO MEDIAL PTERYGOID It is a motor nerve to medial pterygoid muscle It supplies one or two filaments which passes through otic ganglion to supply tensor tympani and tensor veli palatini.
  73. 73. BRANCHES FROM ANTERIOR DIVISION: Provides motor innervation to the muscles of mastication sensory innervation to the mucous membrane of the cheek and buccal mucous membrane of the mandibular molars The anterior division is smaller than the posterior division It runs forward under the lateral pterygoid muscle for a short distance and then reaches the external surface of that muscle by passing between its two heads, from this point it is known as buccal nerve.
  74. 74. Under the lateral pterygoid nerve,it gives off some branches, i.e. The deep temporal nerve- to the temporal muscle The masseter nerve- providing motor innervation to masseter muscle Lateral pterygoid nerve- providing motor innervation to the lateral pterygoid muscle
  75. 75. THE BUCCINATOR NERVE: Also known as long buccal nerve Usually passes between the two heads of the lateral pterygoid Reaches the external surface of the muscle follows the inferior part of the temporal muscle emerges under the anterior border of the masseter muscle At the level of occlusal plane of the mandibular 3rd and 2nd molar
  76. 76. Crosses in front of the ramus Enters the cheek through buccinator muscle Provides sensory innervation to: skin over the anterior part of buccinator buccal gingiva of mandibular molars mucobuccal fold in that region The bucaal nerve does not innervate the buccinator muscle,the facial nerve does.
  78. 78. THE POSTERIOR DIVISION Larger division Mainly sensory Divides into Auriculotemporal nerve Lingual nerve Alveolar nerve
  79. 79. AURICULOTEMPORAL NERVE IT HAS TWO ROOTS: encircles the middle meningeal artery runs back under lateral pterygoid on the surface of tensor veli palatini to pass between the sphenomandibular ligament and the neck of the mandible then lateraly behind the the temporomandibular joint in relation with the upper part of the parotid gland emerging from behind the joint it ascends posterior to the superficial temporal vessels over posterior root of the zygoma divides into superficial temporal branches.
  80. 80. BRANCHES OF AURICULOTEMPORAL NERVE: a) two anterior auricular branch-supply the skin of tragus and sometimes small part of adjoining helix b)two branches to external acoustic meatus-supply skin of meatus and the tympanic membrane
  82. 82. The articular branch- supplying the temporomandibular joint Superficial temporal branch- supply skin in the temporal region and connects with the facial and zygomaticotemporal nerves
  83. 83. COMMUNICATIONSIt communicates with facial nerve providing sensory fibres to the skin over the areas of innervation of motor branches of facial nerve It communicates with the otic ganglion providing sensory,secretory and vasomotor fibres to parotid gland
  84. 84. THE LINGUAL NERVE: Second branch of the posterior division of mandibular nerve Runs between the tensor veli palatini and lateral pterygoid,where it is joined by chorda tympani branch of facial nerve from here It decends to rest between the ramus and medial pterygoid muscle in the pterygomandibular space
  85. 85. It runs anterior and medial to the inferior alveolar nerve whose path is parallel to it. It then continues to reach the side of the base of the tongue slightly below and behind the mandibular 3rd molar. Here it lies just below the mucous membrane in the lateral lingual sulcus.
  86. 86. It then proceeds anteriorly across the muscles of the tongue Looping medial to submandibular duct (wharton’s duct) to deep surface of submandibular and sublingual gland where it breaks up into terminal branches
  89. 89. SUPPLY OF LINGUAL NERVE Supplies the mucosa of the floor of the mouth lingual gingivae Mucosa of anterior two third of the tongue Also carries postganglionic fibres from submandibular ganglion to sublingual and anterior lingual glands APPLIED ANATOMY Lingual nerve is at great risk during surgical removal of impacted third molar During removal of submandibular salivary gland,during which the duct must be dissected from
  90. 90. INFERIOR ALVEOLAR NERVE Largest branch of the mandibular division Descends medial to the lateral pterygoid muscle and lateroposterior to lingual nerve Passes between the sphenomandibular ligament and the mandibular ramus to enter the mandibular canal via mandibular foramen Through out its path it is accompanied by inferior alveolar artery and inferior alveolar vein Nerve travels anteriorly in the canal till it reaches the mental foramen
  91. 91. Inferior Alveolar Nerve mental nerve nerve incisive APPLIED ANATOMY:-Lower lip and tongue is also anaesthetized during I.A.N.B,hence young child or physically or medically handicaaped patients should be informed prior to administration to avoid soft
  93. 93. THE INCISIVE NERVE Continues forward in the bony canal giving off branches to: premolar canine incisors associated labial gingiva THE MENTAL NERVE Exists the canal through the mental foramen between and just below the apices of the premolar,and divides into three branches that innervates: skin of the chin skin of the lower lip buccal mucous membrane from second premolar to the
  94. 94. MENTAL NERVE
  95. 95. THE MYLOHYOID NERVE Just before entering the mandibular canal, the inferior alveolar nerve gives off a small mylohyoid branch It pierces the sphenomandibular ligament and enters a shallow groove on medial surface of mandible Follows a course roughly parallel to inferior alveolar nerve passes below the origin of mylohyoid muscle lies superficial to the surface of mylohyoid muscle
  96. 96. It is a mixed nerve Provides motor innervation to: mylohyoid and anterior belly of digastric of sensory fibres to inferior and anterior surfaces mental protuberance mandibular incisors (sometimes)
  97. 97. GANGLIA ASSO WITH THE TRIGEMINAL NERVE 1.CILLIARY GANGLION connected with nasocilliary nerve by ganglionic branches in orbit, non synapsing sensory for orbit
  98. 98. 2.PTERYGOPALATINE GANGLION: connected to maxillary nerve in infratemporal fossa sensory to orbital septum, orbicularis and nasal cavity, maxillary sinus , palate , nasopharynx.
  99. 99. 3. OTIC GANGLION: lies between trunk of mandibular nerve and tensor palatini , nerve to med pterygoid passes through but does not synapse in the ganglion.
  100. 100. 4.SUBMANDIBULAR GANGLION: related to lingual nerve,rest on hypoglossus supplies post erior ganglionic Parasympathetic secretomotor fibres to submandibular and sublingual gland.
  101. 101. APPLIED ANATOMY :1.Trigeminal neuralgia. 2. Herpes zoster ophthalmicus. 3.Wallenberg Syndrome. 4. Nerve blocks of maxillary and mandibular region.
  102. 102. 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)
  103. 103. 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 Infections :- granulomatous and non granulomatous infections involving 5th cranial nerve.
  104. 104. postherpetic neuralgia Demyelinating conditions Multiple sclerosis (MS) Petrous ridge compression Intracranial vascular abnormalites
  105. 105. 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.
  106. 106. 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 involve; most commonly mandibular > maxillary >ophthalmic
  107. 107. Clinical characteristics:sudden unilateral intermittent paroxysmal sharp shooting lancinating shock like pain elicted by slight touching
  108. 108. superficial trigger points which radiates across the distribution of one or more branches of the trigeminal nerve 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
  109. 109. TRIGGER ZONE
  110. 110. 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.
  111. 111. DIAGNOSIS:CLINICAL EXAMINATION with HISTORY is mandatory Response to treatment with tablet of carbamazepine is univeral Injections of local anaesthetic agents into patients trigger zone gives temporarily relief from pain.
  112. 112. TREATMENT:Medical treatment Surgical treatment:Peripheral injections Peripheral neurectomy Cryotherapy Peripheral radiofrequency Neurolysis(thermocoagulation) Gasserian ganglion procedures
  114. 114. 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.
  115. 115. Side effect:c Visual blurring Dizziness Rashes Hepatic dysfunction Leukopenia Thrombocytopenia
  116. 116. 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.
  117. 117. The anaesthetic agent without adrenaline eg bupivacaine with or without corticosteroids is injected  .
  118. 118. 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
  119. 119. 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.
  120. 120. 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
  121. 121. 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. .
  123. 123. GASSERIAN GANGLION PROCEDURS:Includes various procedures:1.Gycerol injection 2.Thermocoagulation 3.Ballon compression
  124. 124. 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. .
  125. 125. 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.
  126. 126. 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 the ganglion root for 1 minute. It destroyes the root fibres.
  127. 127. E 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
  128. 128. Ocular lesions:Eyelid:- Perorbital pain Oedema Hyperasthesia Conjunctivitis Scleritis Corneal scarring Glaucoma
  129. 129. TREATMENT:Acyclovir 800mg 5 times /day within 4 days of onset of rash Analgesics Antibiotic ointments Systemic steroids 60mg/day Corneal grafting
  130. 130. Wallenberg syndrome:a stroke which causes loss of pain/temperature sensation from one side of the face and the other side of the body. ETIOLOGY:In the medulla, the Ascending Spinothalamic Tract (which carries pain/temperature information from the opposite side of the body) is adjacent to the Descending Spinal Tract of the fifth nerve (which carries pain
  131. 131. A stroke cuts off the blood supply to this area Destroys both tracts simultaneously. Results in loss of pain/temperature sensation in a unique “checkerboard” pattern (ipsilateral face, contralateral body) Characteristic diagnostic feature.
  132. 132. Maxillary nerve blocks:-Infra orbital nerve block -Posterior superior nerve block -Nasopalatine nerve block -Greater palatine nerve block
  133. 133. Infra orbital nerve block:Area anaesthetized:Incisors Cuspids Premolar Mesiobuccal root of the first molar Bony support Soft tissue Upper lip Lower eyelid Portion of nose on same side
  134. 134. ANATOMICAL LANDMARKS:Infra orbital ridge Infra orbital depression Supra orbital notch Infra orbital notch Anterior teeth Pupils of the eye
  135. 135. Posterior Superior Nerve Block:Area anesthetized:maxillary molars with the exception of mesiobuccal root of 1st molar buccal alveolar process of maxillary molars periosteum connective tissue mucous membrane
  136. 136. Anatomical Landmarks:Muccobuccal fold and its concavity Zygomatic process of maxilla Infratemporal surface of maxilla Anterior border and coronoid process of ramus of mandible Tuberosity of maxilla Complication:pterygoid plexus puncture maxillary artery perforation
  137. 137. Nasopalatine nerve block:Area anesthetized:Anterior portion of hard palate i.e canine to canine
  138. 138. Anatomical landmarks:Central incisor Incisive papilla in the midline of the palate
  139. 139. Greater Palatine nerve block:Area anesthetized:Posterior portion of the hard palate and overlying structures upto 1st premolar area on the side injected
  140. 140. Anatomical Landmarks:-2ND and 3rd molar -palatal gingival margin of 2nd and 3rd molar midline of palate -a line appox. 1cm from the palatal gingival margin towards the midline of palate
  141. 141. Mandibular nerve blocks:a)Inferior alveolar nerve block b)Incisive nerve block c)Mental nerve block d)Long Buccal nerve block
  142. 142. Inferior alveolar nerve block:Area anesthetised:Body of the mandible inferior portion of the ramus of the mandible. Mandibular teeth. Mucous membrane and the underlying tissues that are anterior to the 1st molar tooth.
  143. 143. Anatomical landmarks :Mucobuccal fold Anterior border of the ramus of the mandible External oblique ridge Retromolar triangle Internal oblique ridge Pterygomandibular ligament Buccal sucking pad Pterygomandibular space
  144. 144. Symptoms of Anesthesia 1. Subjective symptoms – Tingling and numbness of lower lip and when the lingual nerve is affected, the tip of the tongue. 2. Objective symptoms – Instrumentation necessary to demonstrate absence of pain sensation. Complication -facial nerve paralysis -pain due to contact with the bone too forcefully.
  145. 145. Mental nerve block:Area anesthetised:-Buccal mucous membrane anterior to the mental foramen ie the 2nd molar region to midline -skin of lower lip
  146. 146. Indication:-soft tissue biopsies -suturing of soft tissue Contraindicated:-infections -acute inflammation
  147. 147. Landmark:-mandibular premolar -mucobuccal fold at or just anterior to the mental foramen(usualy located between the apices of 1st and 2nd premolars Complication:-hematoma formation
  148. 148. Incisive nerve block:Area anesthetised:-mental+incisive i.e buccal mucous membrane anterior to the mental foramen ie the 2nd molar region to midline skin of lower lip. -pulpal nerve fibres to premolar,canine and incisors
  149. 149. Indication:When dental procedures have to be carried out in anterior region. C/I infection acute inflammation Landmark:same as mental nerve block,except needle should penetrate into the mental foramen.
  150. 150. Long buccal nerve block:Area anesthetized:buccal mucous membrane and mucoperiosteum of mandibular molar region
  151. 151. Landmarks:external oblique ridge retromolar triangle Indication: -surgery in mandibular buccal mucosa supplement inferior alveolar nerve block.
  152. 152. Conclusion:Trigeminal nerve, its anatomic course and branches are very important from a dentist point of view as inadvertant surgical procedure may lead to trigeminal nerve injury. Disorders of Trigeminal nerve are not rare ,knowing about it will help in formulating appropriate diagnosis and treatment thus achieving the best possible recovery of Trigeminal nerve function. Nerve blocks given for carrying various dental procedures involves the various branches of Trigeminal nerve,hence to avoid any complications ,one needs to have a knowledge about the course and branches of the nerve .
  153. 153. BIBIOGRAPHY:Anatomy head and neck ( B.D Chourasia) Gray’s Anatomy Anatomy of cranial Nerves Anatomy for dental Students ( A.S. Moni) Handbook of local anaesthesia by stanley malamed
  154. 154. Textbook of oral and maxillofacial surgery (Neelima Anil Malik) Harrisson text of internal medicine