Trigeminal nerve
- 1. Course of trigeminal nerve & its importance in OMFS Anchal Mehra PG OMFS
- 2. Contents • Introduction • Anatomy • Clinical examination • Clinical importance • Nerve injury • Related pathology • Conclusion • References
- 3. INTRODUCTION It’s motor to the muscles of 1st branchial arch & several small muscles. It’s sensory to the head & face region.
- 4. • At the level of the pons,anterolaterally, the sensory nuclei merge to form a sensory root. • The motor nucleus continues to form a motor root. • Nerve leaves the anterior aspect of the pons as a small motor root and a large sensory root, and it passes forward, out of the posterior cranial fossa, to reach the apex of the petrous part of the temporal bone in the middle cranial fossa.
- 5. Functional component • Special visceral efferent (SVE) fibers- arise from motor nucleus of CN5, & supply muscles of mastication,mylohyoid,anterior belly of diagastric,tensor veli palatini,tensor tympani. • General somatic afferent (GSA)- they carry proprioceptive sensation from muscles of mastication, TMJ, teeth & terminate in the motor nucleus. Exteroceptive sensation (i.e, pain.touch & temperature ), from skin of the head & face,,nasal cavity,meninges etc. & terminate in the principal nucleus of CN5
- 6. Sensory root GSA- face,scalp,teeth,gingiva,oral & nasal cavities, para nasal sinus, conjunctiva, cornea.
- 7. Motor root CNS Motor nucleus Motor root Mandibular nerve Muscles of mastication, mylohyoid,tensor tympani,tensor veli palatini.
- 8. Trigeminal ganglion 1. Largest sensory ganglion in body. Cresent & flat in shape. 2. Approximately, 1 x 2 cms, covexity face anteriorly & downward. 3. Medially, it is in relation with the internal carotid artery and the posterior part of the cavernous sinus. 2. Lies under meningeal dura , lateral to the cavernous sinus in meckle’s cave on the apex of petrous temporal bone in middle cranial fossa.
- 9. Divisions • The peripheral aspect of the trigeminal ganglion gives rise to 3 divisions: • ophthalmic (V1), • maxillary (V2) and • mandibular (V3).
- 10. OPHTHALMIC NERVE • Purely sensory. • It runs forward in the lateral wall of the cavernous sinus in the middle cranial fossa and divides into three branches, which enter the orbital cavity through the superior orbital fissure.
- 12. Frontal nerve • After emerging from the ophthalmic nerve , it enters the superior part of the superior orbital fissure.
- 13. Frontal nerve • Runs forward between the levator palpebrae superioris muscle and periosteum of the ROOF of the orbit. • About midway across the orbit, it divides into the supraorbital and supratrochlear nerves.
- 14. supraorbital • Continues anteriorly to supra orbital foramen. • Supplies frontal sinus • Ascends superiorly along the scalp. • Supply skin of forehead & scalp as far as lambdoid suture. supratrochlear • Supplies conjunctiva & skin of the medial aspect of upper eye lid. • Supplies the frontal sinus • Skin of the forehead & scalp.
- 15. Lacrimal nerve • In the orbit it travels on the superior border of the lateral rectus with the lacrimal artery. • It receives a communication from the zygomatic nerve through which secretory fibres pass to the lacrimal gland. The lacrimal nerve then enters the lacrimal gland and gives branches to the conjunctiva and the skin of the lateral part of upper eyelid.
- 16. Nasocilliary nerve • Runs along the medial wall of the orbit, within the tendinous ring, giving branches to nasal cavity & ending in the skin at the root of the nose.
- 17. Branches 1. Sensory root to the ciliary ganglion. 2. Long & short ciliary nerves 3. Posterior ethmoidal nerve 4. Anterior ethmoidal nerve 5. Infratrochlear nerve
- 18. Posterior ethamoidal • Travels deep to the superior oblique m. to pass through the posterior ethmoid foramen. • Supplies the sphenoid sinus and the posterior ethmoid sinus. Anterior ethamoidal • Enters the anterior ethmoid foramen and travels through the canal to enter the anterior cranial fossa • Supplies the anterior and middle ethmoid sinus before entering and supplying the nasal cavity • Terminates as the external & internal nasal n. on the face. Infratrochlear • Passes anteriorly on the superior border of the medial rectus m. • Passes inferior to the trochlea toward the medial angle of the eye. • Supplies the skin of the eyelids and bridge of the nose, the conjunctiva.
- 19. Maxillary nerve
- 21. Branches within mid cranial fossa • Meningeal branch- supplies the meninges.
- 22. BRANCHES WITHIN THE PTERYGOPALATINE FOSSA Posterior superior alveolar Zygomatic Ganglionic branches Infraorbital
- 23. • Zygomatic -Passes through the inferior orbital fissure to enter the orbit. • Passes on the lateral wall of the orbit and branches into the zygomaticotemporal and zygomaticofacial branches • The zygomaticotemporal branch gives parasympathetic secretomotor fibers to the lacrimal gland via the lacrimal nerve. Supply the skin on side of the forehead.
- 24. • Zygomaticofacial nerve- traverse inferolaterally in the orbit , emerging through a zygomaticofacial foramen in zygomtic bone, perforating orbicularis oculi. supply the skin on the prominence of the cheek.
- 25. • PSA- Passes through the pterygomaxillary fissure in the infratemporal fossa, it passes on the posterior surface of the maxilla along the region of the maxillary tuberosity. • Supplies maxillary sinus, 1st molar except mesiobuccal root, gingiva & mucosa of the same.
- 26. • Ganglionic branches- two short nerves that suspend the pterygopalatine ganglion in the pterygopalatine fossa. • They also contain postganglionic parasympathetic fibers from the pterygopalatine ganglion & from the zygomaticotemporal nerve, that are going to the lacrimal gland.
- 27. Branches of pterygopalatine nerve- • supply 4 areas – orbit, nose,palate, pharynx. • Through inferior orbital fissure, some branches goes to the orbit. • Supply sphenoidal sinus mucosa,ethmoidal sinus mucosa & orbital periosteum. Orbital part
- 28. Nasal branch • From sphenoapalatine foramen-gives nasal branch, also known as posterior superior nasal branch. • This nasal branch has 2 branches- posterior superior medial & post. Sup. Lateral. • Post. Sup. Medial comes to the palate through the incisive canal & then from both the sides into incisive foramen as nasopalatine nerve, supplying the sensation to palatal mucosa in premaxilla region
- 29. Palatine branches • The palatine branches include- greater palatine & lesser palatine branches. • GP decends down through pterygopalatine canal,emerging on hard palate through GP foramen,supplying sensory innervation as far as till premolar area. • The lesser palatine nerves emerge from LP foramen n goes posteriorly supplying the soft palate,tonsillar region.
- 30. Pharyngeal part • Pharyngeal part – small branch leaves PPG & passes through the pharyngeal canal & supply nasopharynx,posterior to auditory tube.
- 31. • Infraorbital- Passes through the inferior orbital fissure to enter the orbit. • Passes anteriorly through the infraorbital groove and infraorbital canal and exits onto the face via the infraorbital foramen as cutaneous branch of V2. • Branches – palpebral, nasal, superior labial.
- 32. Terminal branchesin the face : a)Palpebral: to the lowereyelid. b)Nasal: to the sideof thenose. c)SuperiorLabial: to the upperlip.
- 33. Branches within INFRAORBITAL CANAL • MSA - variable nerve. • When present, branches off the infra orbital nerve,while travelling in the infra orbital canal. • which supplies the maxillary sinus as well as the upper premolar, mesiobuccal root of 1st molar & the gums, and the mucosa alongside the same teeth.
- 34. • ASA- while in the canal, has a small branch that supplies the nasal cavity in the region of the inferior meatus and inferior corresponding portion of the nasal septum. • As it descends down, it innervates part of the maxillary sinus; anterior teeth and the gingiva and mucosa alongside the same teeth.
- 35. Mandibular nerve • The largest division of the trigeminal nerve. • It is a mixed nerve has a sensory root and a motor root. • It leaves the skull through the Foramen Ovale • Below foramen ovale, the 2 roots unit to form the trunk of the nerve. • Then , it divides into anterior & posterior divisions
- 36. Branches From the Main Trunk • Meningeal branch- re-enters the cranium through foramen spinosum with the middle meningeal artery & and supply the dura matter. • Nerve to the medial pterygoid muscle, which supplies not only the medial pterygoid, but also the tensor veli palatini muscle &tensor tympani. • Nerves to tensor tympani, and tensor veli palatini muscles
- 37. Branches From the Anterior Division • Masseteric nerve to the masseter muscle • Deep temporal nerves to the temporalis muscle, anterior & posterior. • Nerve to the lateral pterygoid muscle • Buccal nerve to the skin and the mucous membrane of the cheek .It is the only sensory branch of the anterior division of the mandibular nerve.
- 38. Branches From the Posterior Division • Auriculo temporal • Lingual • Inferior alveolar • Mylohyoid
- 39. Auriculotemporal nerve • Supplies the skin of the auricle, the external auditory meatus, the temporomandibular joint, and the scalp. • This nerve also conveys parasympathetic secretomotor fibers from the otic ganglion to the parotid salivary gland. a. Anterior Auricular b. Branches to external acoustic meatus c. Articular d. Parotid e. Superficialtemporal
- 40. Lingual nerve • which descends in front of the inferior alveolar nerve and enters the mouth . • It then runs forward on the side of the tongue and crosses the submandibular duct. • In its course, it is joined by the chorda tympani nerve, and it supplies the mucous membrane of the anterior two thirds of the tongue and the floor of the mouth. • It also gives off parasympathetic secretomotor fibers to the submandibular ganglion.
- 41. Inferior alveolar nerve • Enters the mandibular canal to supply the teeth of the lower jaw and emerges through the mental foramen (mental nerve) to supply the skin of the chin . • Before entering the canal, it gives off the mylohyoid nerve, which supplies the mylohyoid muscle and the anterior belly of the digastric muscle.
- 42. • Incisivenervewhich continues forwards .It supplies the canine and incisor teeth of the lower jaw.
- 43. • The inferior alveolar nerve within the mandibular canal, forms the inferior dental plexus, which innervates the lower teeth. • A major branch of this plexus, the mental nerve, supplies the skin and mucous membranes of the lower lip, skin of the chin, and the gingiva of the lower teeth.
- 44. 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 and nasal cavity, max sinus, palate, nasopharynx. 3. Otic Ganglion:below foramen ovale in infra temporal fossa. On the medial surface of mandibular nerve. Supplies secretomotor fibres to the parotid gland. 4.Submandibular Ganglion: related to lingual nerve, rests on hypoglossus . supplies post ganglionic parasympathetic secretomotor fibres to submandibular and sublingual gland.
- 46. Examination of the Trigeminal Nerve • Testing motor supply • Test for corneal reflex • Testing sensory supply • Testing jaw jerk
- 47. Clinical Relevance • Testing sensory supply: ask the patient to close their eyes and introduce a cotton wisp to areas of the face supplied by the three divisions of the trigeminal nerve to detect tactile sensory competence. • Testing motor supply: ask the patient to clench their jaw as you palpate superior to the zygomatic arch to feel for contraction of the temporalis and then repeat palpating inferiorly for the masseter. Ask the patient to open their mouth and deviate their mandible to the right and left to check for competence of the medial and lateral pterygoid muscles.
- 48. • Corneal Reflex • The corneal reflex is the involuntary blinking of the eyelids – stimulated by tactile, thermal or painful stimulation of the cornea. • In the corneal reflex, the ophthalmic nerve acts as the afferent limb – detecting the stimuli. • The facial nerve is the efferent limb, causing contraction of the orbicularis oculi muscle. • If the corneal reflex is absent, it is a sign of damage to the trigeminal/ophthalmic nerve, or the facial nerve.
- 49. Testing jaw jerk • Place a finger on the chin & is tapped at a downward angle while the mouth is held slightly open. • In response, muscles will jerk the mandible upwards. Normally this reflex is absent or very slight. • In upper motor neuron lesions, above the level of the pons, the closure is brisk.
- 50. Clinical pathology • TRIGEMINAL NEURALGIA (TIC DOULOUREUX) • It’s a clinical condition which presents itself as paroxysmal episodes of acute pain of sudden onset and brief duration in the area of distribution of 1 or more branches of the trigeminal nerve,usually the 2nd & 3rd divisions. • The anticonvulsive agents, carbamazepine or oxcarbazepine, constitute the first-line treatment. Microvascular decompression or ablative procedures should be considered when pharmacotherapy is ineffective or intolerable.
- 52. TCR • TCR is a triad of bradycardia ,bradypnea and gastric motility changes due to the efferent activation of the vagal nerve in response to the pressure distribution in the trigeminal nerve. • This unexpected phenomenon is usually seen in orbital injuries and during surgical manipulation of craniofacial structures in the distribution of trigeminal nerve.
- 53. • Knowledge of the TCR is essential as it may mimic a closed cranial injury or a cardiac dysarrythmia in a post traumatic patient to avoid unwarranted surgical intervention. • A detailed ophthalmic examination in maxillofacial injuries is essential.
- 55. LESIONS • Lesion at foramen rotundum or within infra orbital canal involves maxillary nerve. This results in paraesthesia of the cheek & upper teeth. • Loss of sneeze reflex as the nerve supplies the afferent limb of ‘’sneeze reflex’’. •Lesion at the foramen ovale involves mandibular nerve & paraesthesia along the mandible, lower teeth,& side of the face. •Paralysis of muscles of mastication . •Loss of the ‘’ jaw jerk reflex ‘’, as mandibular nerve supplies both the afferent & efferent limbs for the jaw jerk reflex.
- 56. Multiple scelrosis • During periods of multiple sclerosis (MS) activity, white blood cells are drawn to regions of the white matter. • These initiate and participate in the inflammatory response. • During the inflammatory phase, the myelin surrounding the axons is destroyed in a process known as demyelination. • Approximately 2 % of patients with MS also have symptoms of trigeminal neuralgia.
- 57. Herpes zoster of CN V
- 58. Trigeminal Schwannomas • Arise from the trigeminal ganglion and cause numbness and paresthesias are the most common symptoms from these tumors, but pain and crawling sensations are sometimes present. • Other tumors and perineurial spread of other cancers in the region of the trigeminal ganglion are rare, but can cause variable clinical symptoms.
- 59. The superior orbital fissure syndrome • Is a complex of impaired function of the cranial nerves (III, IV, V, and VI) that enter the orbit through the superior orbital fissure. • Three major precipitating factors for SOFS are trauma, tumor, and inflammation. • Any unnatural narrowing of SOF due to trauma of high impact to the upper and midface (frontobasal skull, Le Fort II, III, and zygomatic complex fractures) can precipitate this condition.
- 60. CLASSIFICATION OF NERVE INJURY • Seddon’s Classification(1943) • Sunderland’s Classification(1951)
- 61. Nerve injuries Neuropraxia • the mildest injury type that is transient. • There is no effect on nerve continuity. • Caused by a temporary disturbance in the conduction pathway that blocks neural transmission but does not damage the axon. • Symptoms include numbness, tingling, and loss of vibration and postural sensation. • All of these effects resemble the common effects of local anesthesia. • This type of injury will recover completely providing the cause, for example, ongoing compression, is removed
- 62. Axonotmesis – Complete interruption of nerve fibres but the connective tissue is still intact. – complete loss of motor, sensory, and autonomic function. – Tinel’s sign can be elicited initially at the site of the injury and will advance distally over time
- 63. Neurotmesis – Neurotmesis involves complete severance of the nerve. – Complete functional loss and recovery without surgical intervention is unlikely. – There is a complete loss of motor and sensory function. – Recovery can only occur after appropriate surgical repair of the nerve – on clinical examination and neurophysiology assessment may be the same for axonotmesis and neurotmesis, yet there is a clear difference in prognosis and management.
- 65. TRIGEMINAL NEUROPATHY • Well recognized disorders characterized and manifesting as skin and mucosal numbness in the region innervated by the trigeminal nerve. • Facial numbness indicates trigeminal sensory alteration affecting the trigeminal system • They can be the result of traumatism, tumors, or diseases of the connective tissue, infectious or demyelinating diseases, or may be of idiopathic origin. • The clinical exploration reveals a loss of sensitivity in the cutaneous territory corresponding to the affected nerve, which can be partial (hypoesthesia) or complete (anesthesia).
- 66. Trigeminal nerve injuries • CN5 may be injured by trauma,tumors,aneurysms or meningeal infections. • The sensory & motor nuclei in the pons & medulla may be destroyed by intermedullary tumors or vascular lesions. • An isolated lesion of the spinal trigeminal tract also may occur with multiple sclerosis.
- 67. INJURY CAUSES THE FOLLOWING- • Paralysis of muscle of mastication with deviation of the mandible towards the side of the lesion. • Loss of the ability to appreciate soft tactile,thermal or painful sensations in the face. • Loss of corneal reflex & sneezing reflex.
- 68. • Eg: involvement of the IAN in mandibular fractures and infra -orbital in maxillary and ZMC fractures • Loss or diminished sensation around the lower lips ,usually involving the lower lip and/or tongue areas causing a mixture of pain, numbness that may be present all the time or intermittently.
- 69. • Lingual nerve lies in contact with lingual gingiva medial to 3rd molar, may get injured during removal of the tooth.
- 70. Conclusion
- 71. Bibliography • Snell’s 8th edition • Textbook of Local Anesthesia-Stanley F Malamed • Gray’s Anatomy • Articles • Internet sources
- 72. Thank you
- 73. Applied anatomy • Supraorbital injuries Trauma to the supraorbital margin may damage the supraorbital and/or supratrochlear nerves causing sensory loss in the scalp. • Ethmoid tumours Malignant tumours of the mucous lining of the ethmoid air cells may expand into the orbits, damaging branches of Va. 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 external nasal nerve as it becomes superficial. Sensory loss of the skin down to the tip of the nose.
- 74. • Infraorbital injuries: malar fractures Trauma to infraorbital margin may cause sensory loss of infraorbital skin. • Maxillary sinus infections Infections of the maxillary sinus may cause infraorbital pain or may cause referred pain to other structures supplied by Vb . • Maxillary teeth abscesses :The roots of the maxillary teeth (especially the second molars)are intimately related to the maxillary sinus. Root abscesses are painful. • Maxillary antrumtumours Malignant tumours of the mucous lining of the maxillary antrum may expand into the orbit, damaging branches of Vb, particularly the infraorbital. This may lead to anaesthesia over the facial skin. The orbital contents may also be displaced causing proptosis
- 75. • TCR is actually endogenous physiological protective mechanisms found in brain against ischemia. • It is one of the oxygen conserving reflexes. • Within seconds of initiation of such reflex, there is activation of sympathetic nerves which leads to cerebro vascular vasodilatation. • These responses are exaggerated and put the patient at risk . • During initial period of vagal stimulation,the cardiac depression is at peak.
- 76. Management of nerve injury 1.Manipulation of the nerve (neurolysis) 2.Repair with a direct anastomosis or the use of graft 3.Coaptation 4.Neurorrhaphy 5. Entubulation