TRIGEMINAL NERVE

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TITLE OF SEMINAR TRIGEMINAL NERVE SUBMITTED BY: Dr. VAIBHAV MOTGHARE DEPARTMENT OF PUBLIC HEALTH DENTISTRY AT I.T.S DENTAL COLLEGE, HOSPITAL & RESEARCH CENTRE, GREATER NOIDA 8 th August2012 Instructor: Dr. MANSI ATRI MODERATOR: Dr. JAYAPRAKASH K

INTRODUCTION:

INTRODUCTION The trigeminal or the 5 th nerve is the main nerve for the head and neck region due to its wide course and distribution all over the area. The trigeminal nerve transmits sensation from the skin of the anterior part of the head, the oral and nasal cavities, the teeth and the meninges . It has three divisions (ophthalmic, maxillary and mandibular ) subsequently treated as separate nerve. 2

ORIGIN OF TRIGEMINAL NERVE:

ORIGIN OF TRIGEMINAL NERVE 3

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The three nerves arise from a large semilunar trigeminal ganglion which lies in the trigeminal fossa . The ganglion is connected to pons by a thick sensory root. There is another smaller motor root which emerges from pons just medial to the sensory root. It enters the foramen ovale to join the mandibular nerve. 4

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FUNCTIONAL COMPONENTS:

FUNCTIONAL COMPONENTS 1. General somatic afferent: recieves exteroreceptive sensations from the skin of face and mucosal surfaces and proprioceptive impulses from the muscles of mastication. 2. Special visceral efferent: motor to nucleus of 1 st branchial arch. 6

NUCLEAR ORIGIN:

NUCLEAR ORIGIN The sensory nuclei: this nuclei contains fibres which are arranged in 3 groups: a. chief sensory nucleus- concerned with sensation of touch from face. b. spinal nucleus (nucleus of spinal tract)- concerned with sensation of pain and temprature from all trigeminal areas. c. mesencephalic nucleus- these fibres do not have their cell bodies in the ganglion, and are the only 1 st order neurons in the CNS. 7

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2. The motor nucleus: this lies in the pons , close to the medial side of the chief sensory nucleus. Fibers emerge from the lateral aspect of pons as the motor root is lying just medial to the sensory root. 8

ORIGIN:

ORIGIN Being the largest cranial nerve, it constitutes the main course and supply over the head and neck region. The course of trigeminal nerve starts at the lateral aspect of pons , near middle cerebellar peduncle, where it is attached. Then it passes below tentorium cerebelli , to middle cranial fossa , and forms the trigeminal ganglion in the trigeminal fossa on the temporal bone. 9

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From the trigeminal ganglion, it splits into 3 branches-ophthalmic ( Va ), maxillary ( Vb ) and mandibular ( Vc ). The trigeminal ganglion contains cell bodies of primary sensory neurons in all three divisions of trigeminal nerve. It is partially surrounded by cerebrospinal fluid in recess of subarachnoid space. 11

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TRIGEMINAL GANGLION OPTHALMIC MAXILLARY MANDIBULAR TRIGEMINAL MOTOR NUCLEUS 12

CLINICAL APPLICATION OF TRIGEMINAL GANGLION:

CLINICAL APPLICATION OF TRIGEMINAL GANGLION Shingles and varicella -zoster: The trigeminal ganglion, as any sensory ganglion, may be the site of infection by the herpes zoster virus causing shingles, a painful vesicular eruption in the sensory distribution of the nerve. Trigeminal neuralgia (tic douloureux ): This is severe pain in the distribution of the trigeminal nerve or one of its branches, the cause often being unknown. It may require partial destruction of the ganglion. 13

OPTHALMIC NERVE (Va):

OPTHALMIC NERVE ( Va ) It originates from trigeminal ganglion in middle cranial fossa and passes anteriorly through lateral wall of cavernous sinus. It then divides into three branches: frontal (largest), nasociliary and lacrimal (smallest) which passes through the superior orbital fissure to the orbit. 14

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The Frontal nerve passes immediately below frontal bone and divides into supraorbital (larger, lateral) and supratrochlear (medial) nerves. The supraorbital nerve turns up to supply skin of forehead and scalp. The supratrochlear nerve supplies the conjunctiva, upper lid and the skin of lower part of forehead. 15

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The nasociliary nerve enters the orbit within the tendinous ring of superior orbital fissure. It gives off 5 branches: 1. sensory communicating branch 2. long ciliary nerves: supplies the iris and cornea. 3. posterior ethmoidal nerve: supplies ethmoidal and sphenoidal sinuses. 4. anterior ethmoidal nerve: supplies the nasal septum and lateral wall of nose. 5. infratrochlear nerve: supplies the skin of both eyelids. 16

REGION OF OPTHALMIC NERVE:

REGION OF OPTHALMIC NERVE SUPRAORBITAL SUPRATROCHLEAR REGION OF NASOCILLIARY LACRIMAL 17

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The lacrimal nerve also enters the orbit through the superior orbital fissure. It runs along the lateral wall of the orbit and ends in lacrimal gland. This nerve supplies the lacrimal gland and the conjunctiva and finally pierces the orbital septum to supply the lateral part of upper eyelid. 18

CLINICAL APPLICATION:

CLINICAL APPLICATION Ethmoid tumours Malignant tumours of the mucous lining of the ethmoid air cells may expand into the orbits, damaging branches of opthalmic nerve. This may lead to displacement of the orbital contents causing proptosis and squint, and sensory loss over the anterior nasal skin. Nasal fractures Trauma to the nose may damage the nasociliary nerve. Sensory loss of the skin down to the tip of the nose may result. 19

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Corneal reflex: When the cornea is touched, usually with a wisp of cotton, the subject blinks. This tests V and VII. The nerve impulses pass through cornea and then through nasociliary nerve to the brain. Supraorbital injuries Trauma to the supraorbital margin may damage the supraorbital and supratrochlear nerves causing sensory loss in the scalp. 20

MAXILLARY NERVE (Vb):

MAXILLARY NERVE ( Vb ) It again originates from the trigeminal ganglion in middle cranial fossa and passes in lower part of lateral wall of cavernous sinus. Here it gives off a small meningeal branch which supplies the wall of the middle cranial fossa . Now the nerve passes through foramen rotundum to the pterygopalatine fossa where it divides into main branches, infraorbital and zygomatic , and gives other branches to nose, palate and upper teeth. 21

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The infraorbital nerve passes anteriorly between orbit and maxillary antrum in the infraorbital groove. Here, twigs to mucosal lining of maxillary antrum are sent. Finally it emerges at infraorbital foramen to supply skin over cheek and upper lip. Zygomatic nerve: It enters orbit through inferior orbital fissure. Two small cutaneous branches penetrate the zygoma : the zygomaticofacial and zygomaticotemporal . It conveys postganglionic parasympathetic fibers from pterygopalatine ganglion to lacrimal gland. 22

REGION OF MAXILLARY NERVE:

REGION OF MAXILLARY NERVE ZYGOMATIC REGION SUPERIOR ALVELOLAR REGION INFRAORBITAL REGION 23

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Nasal branches: Passes through sphenopalatine foramen into nasal cavity and supplies nasal cavity and sinuses. Superior alveolar (dental) nerves: Branches of infraorbital and palatine nerves pass directly through maxilla to maxillary teeth, gums and sinus. Greater and lesser palatine nerves: these are responsible for hard and soft palate sensations. Branches also convey parasympathetic fibres to minor salivary glands in the palatal mucosa. Pharyngeal branch: Passes posteriorly to contribute to sensory supply of nasopharynx . 24

CLINICAL APPLICATION:

CLINICAL APPLICATION Infraorbital injuries ( malar fractures): Trauma to infraorbital margin may cause sensory loss of infraorbital skin. Maxillary antrum tumours : Malignant tumors of the mucous lining of the maxillary antrum may expand into the orbit, damaging branches of maxillary nerve, particularly the infraorbital . This may lead to anaesthesia over the facial skin. 25

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Maxillary sinus infections: Infections of the maxillary sinus may cause infraorbital pain or may cause referred pain to other structures supplied by maxillary nerve e.g. upper teeth. Maxillary teeth abscesses: The roots of the maxillary teeth (especially the second molars) are intimately related to the maxillary sinus. Root abscesses are painful. 26

MANDIBULAR NERVE (Vc):

MANDIBULAR NERVE ( Vc ) The mandibular nerve is a mixed sensory and motor nerve. It origins from trigeminal ganglion in the middle cranial fossa and passes through foramen ovale to reach the infratemporal fossa with four main branches: inferior alveolar, lingual, auriculotemporal , buccal . Other branches of mandibular nerve are small twigs to muscles supplied as motor branches. 27

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Inferior alveolar nerve: it enters the mandibular foramen and supplies lower teeth. Just before mandibular foramen, it gives off a nerve to mylohyoid and anterior belly of digastric , running in groove on medial aspect of mandible. The main trunk of the inferior alveolar nerve supplies the lower teeth and its adjoining skin. Mental nerve is a continuation of inferior alveolar nerve and emerges from mental foramen on anterior aspect of mandible to supply skin. 28

REGION OF MANDIBLAR NERVE:

REGION OF MANDIBLAR NERVE AURICULO-TEMPORAL BRANCHES OF BUCCAL INFERIOR ALVEOLAR AND MENTAL 29

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Lingual nerve is responsible for tongue sensation. The lingual nerve lies immediately below and medial to the third lower molar and passes forwards in floor of mouth, winding around submandibular duct. It supplies anterior part of tongue and gums. Buccal nerve: it supplies sensory fibres to skin and mucosa of cheek except buccinator . Muscular branches: temporal nerves to temporalis , and other muscular twigs to masseter , medial & lateral pterygoids , mylohyoid , anterior belly of digastric , tensor tympani and tensor palati . 30

MOTOR BRANCHES OF THE MANDIBULAR NERVE:

MOTOR BRANCHES OF THE MANDIBULAR NERVE 31

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Auriculo -temporal nerve: it arises beneath foramen ovale by two rootlets on either side of middle meningeal artery. Then it passes above parotid gland, between TMJ and external auditory meatus to emerge on side of head. Ultimately it ascends close to superficial temporal artery. It supplies TMJ, parotid fascia, skin of temple, most of skin of external auditory meatus and tympanic membrane. 32

CLINICAL APPLICATION:

CLINICAL APPLICATION Lingual nerve: Careless extractions of the third lower molar, abscesses of its root, or fractures of the angle of the mandible may all damage the lingual nerve. This may result in loss of somatic sensation from the anterior portion of the tongue and loss of taste sensation. Inferior alveolar nerve: Trauma to the mandible may damage or tear the inferior alveolar nerve in the mandibular canal leading to sensory loss distal to the lesion. 33

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Mumps: Mumps is inflammation of the parotid gland causing tension in the parotid capsule which is innervated by the auriculotemporal nerve. It gives both local tenderness and referred ear ache. Submandibular duct: The intimate relationship between the submandibular duct and the lingual nerve is significant in duct infections and surgery. If the lingual nerve were damaged during a submandibular surgery, there would be sensory loss, both somatic and taste, in the anterior portion of the tongue. 34

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Referred pain to the ear: Disease of the TMJ or swelling of the parotid gland may cause ear ache because of referred pain. Also, pain from the lower teeth, oral cavity and tongue may be referred to the ear. Superficial temporal artery biopsy: The auriculotemporal nerve accompanies the superficial temporal artery on the temple. In cases of temporal arteritis , the nerve is anaesthetized so that the overlying skin can be incised to obtain a biopsy of the artery. 35

OVERALL SUMMARY OF DISTRIBUTION OF BRANCHES OF TRIGEMINAL NERVE:

OVERALL SUMMARY OF DISTRIBUTION OF BRANCHES OF TRIGEMINAL NERVE OPTHALMIC MAXILLARY MANDIBULAR 36

OVERALL ACTUAL DISTRIBUTION:

OVERALL ACTUAL DISTRIBUTION 37

LESIONS ASSOCIATED WITH INTRACRANIAL PART OF TRIGEMINAL:

LESIONS ASSOCIATED WITH INTRACRANIAL PART OF TRIGEMINAL Infections and neoplasia most commonly involve the peripheral divisions of the trigeminal nerve rather than the intracranial part. The Meckel’s cavity can be involved either by extrinsic or intrinsic disease. Extrinsic lesions, usually bony metastasis, chordoma , or chondrosarcoma, destroy adjacent bone as they extend toward the Meckel’s cavity. Intrinsic lesions simply expand the Meckel’s cavity. 38

BILATERAL MECKEL’S CAVITY EXPANSION IN LEUKEMIA:

BILATERAL MECKEL’S CAVITY EXPANSION IN LEUKEMIA 39

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Pituitary fossa and cavernous sinus lesions may extend to the Meckel’s cavity or involve the cavernous portion of the trigeminal nerve divisions as well. The trigeminal nerve has three sensory and one motor nuclei. The sensory nuclei are the principal, mesencephalic , and spinal sensory. The cervical extension of the spinal sensory nucleus explains the relation of upper cervical disk herniation and its association with trigeminal sensory neuropathy. 40

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Multiple sclerosis, glioma , and infarction are the most common brainstem and upper cervical cord lesions resulting in fifth cranial nerve symptom. Less common lesions include metastasis, cavernous hemangiomas , hemorrhage, and arteriovenous malformation. Rarely, rhombencephalitis may develop as a result of retrograde extension of herpes simplex virus type 1 from the trigeminal ganglion into the brainstem. 41

THE AURICULOTEMPRAL NERVE SYNDROME(FREY SYNDROME):

THE AURICULOTEMPRAL NERVE SYNDROME(FREY SYNDROME) Consists of flushing and sweating of the ipsilateral face in the distribution of the auriculotemporal nerve upon eating or tasting. It is occasionally seen following injury or infection of the parotid gland area . 42

THE PARATRIGEMINAL SYNDROME:

THE PARATRIGEMINAL SYNDROME It is also known as the Reader Syndrome and is a rare disorder produced by tumors arising in the semilunar ganglion. Characterised by trigeminal neuralgia at the onest ,followed by facial anesthesias on the affected side. The muscles of mastication are found weakened or paralysed . 43

TRIGEMINAL NEURALGIA:

TRIGEMINAL NEURALGIA Also called as tic douloureux . It is the worst pain known to humankind. Also sometimes named as chronic facial pain syndrome. Most commonly afflicts people in middle or late life. It is caused by hypersensitivity of the Trigeminal Nerve. 44

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The most important characteristic to diagnose this condition is its severity and that it does not crosses the midline. Other types of Facial Pain -Atypical Facial Pain -Dental Neuralgia - Temporo-mandibular Joint Syndrome -Anesthesia Delorosa -Cluster Headaches -Migraine Headaches 45

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Common description of Pain: -Sharp - Lancinating -Like an electrical shock -Sudden in onset. Common relief measures: Avoiding stimulation of facial sensation Medications: – Tegretol ( Carbamazepine ) – Trileptal ( Oxcarbazepine ) – Neurontin ( Gabapentin ) – Dilantin ( Phenytoin ) – Lioresal ( Baclofen ) 46

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Causes that are believed to result in trigeminal neuralgia: -Trigeminal Nerve Hypersensitivity -Vascular Compression of the Nerve Root Entry Zone by: -Multiple sclerosis -Tumor - Arterio -venous malformation All these factors cause damage to the nerve covering (myelin sheath). 47

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Surgical Treatment Options: these methods are the most preferred because they have a high success rate. The surgical methods include: Stop the underlying cause of the pain - Microvascular Decompression: it has the best long term results and has a highest cure rate. Statistics show a 95-99% excellent pain control immediately and a 75-80% cure rate. 48

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Injure the Trigeminal nerve so that patient doesn’t feel the pain: - Trigeminal nerve avulsion(peripheral neurectomy ) -Balloon Compression: injures nerve by compression with an inflatable baloon . -Glycerol Injection: glycerol is injected into the trigeminal ganglion. 49

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- Radiosurgery : this technique is least as it takes months to prove its effect. -Radiofrequency Lesion: it is quick and effective but has high recurrence rates. -Injection of 100% alcohol or boiling water in the ganglion: immediately effective but this procedure has to be repeated after sometime. 50

CONCLUSION:

CONCLUSION In conclusion, a variety of conditions may involve the different segments of the trigeminal nerve. Knowledge of its anatomic course and its application allows an understanding of disorders involving the brainstem, the nerve parts and adjacent skull base. 51

REFERENCES:

REFERENCES Textbook of anatomy for dental students, by M.K. Anand , 2 nd ed. Human anatomy: regional and applied, by B.D.Chaurasia , 2 nd ed. Manual of clinical anatomy, by Cunningham, 1 st ed. Cranial nerves: functional anatomy, by Stanley Monkhouse , 1 st ed. 52

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Human anatomy, by McKinley & O'Loughlin , 1 st ed. Cranial nerves and common peripheral lesions, by Lawrence M. Witmer , http://www.oucom.ohiou.edu/dbms-witmer/peds-rpac.htm . 53

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THANK YOU 54