Trigeminal Nerve Robinson 2025 PDF

Trigeminal Nerve DPT, W. Robinson, Ph.D. Nervous System & Pain Temple University Neuroanatomy Disclosure I currently have no relationships of any kind with any company whose products or services in any way relate to the practice of medicine, medical education, or res...

Trigeminal Nerve DPT, W. Robinson, Ph.D. Nervous System & Pain Temple University Neuroanatomy Disclosure I currently have no relationships of any kind with any company whose products or services in any way relate to the practice of medicine, medical education, or research. W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Suggested reading: Neuroscience for Dentistry. O’Kane and Barritt, 2022; – Chapter 20 Teach Me Anatomy articles – The Trigeminal Nerve (CN V) by Nandhaa Pazhaniappan – Ophthalmic Division by Reshma Joseph – Maxillary Division by James Finnie – Mandibular Division by Sam Little W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Learning Objectives – CN V Following today’s presentation, you should be able to: Describe the intra- and extra- cranial courses of the trigeminal nerve and its branches Explain the sensory and motor functions of the trigeminal nerve Describe the locations and functions of the trigeminal nerve nuclei Describe the upper motor neuron pathways that project to the trigeminal motor nuclei Sequence the pathway for the perception of orofacial pain Explain the trigeminal nerve’s role in parasympathetic pathways Localize trigeminal nerve lesions based on the W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Learning Objectives – CN VII Following today’s presentation, you should be able to: Explain the motor and sensory functions of the facial nerve Describe the location of the facial nerve nuclei Describe the intra- and extra- cranial courses of the facial nerve and its branches Describe the upper motor neuron pathways that project to the facial nuclei to explain “forehead sparing” observed in some patients with intracranial lesions Explain the facial nerve parasympathetic pathways, ganglia, and functions Localize facial nerve lesions based on the W. Robinson, DPT, Ph.D. Temple University Neuroanatomy UMN pathways to facial nuclei / “forehead sparing” W. Robinson, DPT, Ph.D. Temple University Neuroanatomy UMN pathways to facial nuclei / “forehead sparing” Axon from left motor cortex, projecting to… Pons: right and left (bilateral) facial motor nuclei W. Robinson, DPT, Ph.D. Temple University Neuroanatomy UMN pathways to facial nuclei / “forehead sparing” Axon from left motor cortex, projecting to… Pons: right and left (bilateral) facial motor nuclei Axon from left motor cortex, projecting to… Pons: only to the right (contralateral) facial motor nucleus W. Robinson, DPT, Ph.D. Temple University Neuroanatomy CN VII motor pathwayforehead Precentral gyrus Rig ht Lef t Axon from right⌃motor cortex, projecting to… Pons: right and left (bilateral) facial motor nuclei mouth Axon from right⌃motor cortex, projecting to… bilateral pons Pons: only to the left (contralateral) facial motor nucleus contralateral pons With the indicated lesion, there is no descending/motor signal from the left orofacial region of the motor cortex W. Robinson, DPT, Ph.D. Temple University Neuroanatomy CN VII motor pathwayforehead Precentral gyrus Rig ht Lef t Axon from right⌃motor cortex, projecting to… Pons: right and left (bilateral) facial motor nuclei mouth Axon from right⌃motor cortex, projecting to… bilateral pons Pons: only to the left (contralateral) facial motor nucleus contralateral pons With the indicated lesion, there is no descending/motor signal from the left orofacial region of the motor cortex LMNs in the left pons (motor nucleus of VII) for forehead and mouth muscles are receiving UMN signals, but the only signal received on the right is for right forehead muscles W. Robinson, DPT, Ph.D. Left CBT Temple University Neuroanatomy 28-year-old woman presents with complete right facial droop, diminished tear production in her right eye, dry mouth, & dysgeusia. Before you localize the lesion, what else do you want to know? W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Deficits (right side): Complete facial droop Dry eye Pterygoid Xerostomia Facial C Greater Canal a nal Dysgeusia Petrosal x Lacrimal Nerve Gland Pterygopalatine (+ Nasal Internal Auditory Meatus Geniculate What else?: Ganglion Ganglion Cavity & Palate) Normal eye movements Unilateral deafness Stapedius (Taste, Anterior 2/3 of Tongue) Intermittent dizziness Chorda Middle Ear Tongue Skin Over Tympani Cavity x Mastoid Process x Stylomastoid Foramen Submandibular x Ganglion Sublingual Gland Muscles of Facial Expression Submandibular Gland (+ Stylohyoid & Posterior Belly of Digastric) From “Temporal Bone and Facial Nerve” lecture (D102) W. Robinson, DPT, Ph.D.  Temple University Neuroanatomy “MRI scan revealed a mass with a maximal diameter of 5.0 cm at the right cerebellopontine angle with petrous bone invasion.” SE REPORT article ont. Surg., 24 May 2022 c. Neurosurgery lume 9 - 2022 | https://doi.org/10.3389/fsurg.2022.759163 W. Robinson, DPT, Ph.D.  Trigeminal Nerve DPT, W. Robinson, Ph.D. Nervous System & Pain Temple University Neuroanatomy Course of Trigeminal Nerve: emerges from mid-pons Optic chiasm CN I CN II Pituitary stalk CN III Mammillary bodies CN IV Cerebral crus CN V CN V CN VI Pons CN VII Cerebellum Pyramid Olive CN VIII CN IX CN X Medulla CN XI (Ventral view) CN XII W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Course of Trigeminal Nerve Superior orbital fissure CNS – Within brainstem Intracranial – Pons to foramina Superior orbital fissure Foramen rotundum Foramen ovale W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Sensory and Motor Functions of CN V Sensory Motor – General – Somatic motor only Sensation (but it’s – All 3 divisions: complicated) – Mandibular division only: Muscles of mastication Suprahyoid muscles: – Anterior belly of digastric – Mylohyoid muscle Tensors: W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Sensory and Motor Functions of CN V1 Sensory Ophthalmic – General Division: V1 Sensation – All 3 divisions: W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Sensory and Motor Functions of CN V2 Sensory Maxillary Division: – General V2 Sensation – Lower eyelid and its – All 3 divisions: conjunctiva – Inferior posterior portion of the nasal cavity (superior anterior is CN V1) – Cheeks and maxillary sinus – Lateral nose – Upper lip, teeth and gingiva W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Sensory and Motor Functions of CN V3 Sensory Mandibular – General Division: V3 Sensation – The facial skin in the – All 3 divisions: lower third of the face, including the chin and lower lip – Inferior row of teeth and gingiva – The anterior two thirds of the tongue General sensation only Taste conveyed by Chorda Tympani (CN VII) W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Sensory and Motor Functions of CN 4V Muscles 3 of 4 Other Muscles Mastication – Tensor veli palatini – Temporalis – Tensor tympani – Masseter – Mylohyoid – Medial pterygoid – Anterior belly of – Lateral pterygoid digastric W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Trigeminal Nerve Nuclei Trigeminal Motor Nucleus – Location: Pons – CN V motor nucleus is in mid pons, with fascicles that join CN V3 = LMN Muscle of – Where is the UMN? mastication – How does the UMN or… communicate with motor nucleus of CN W. Robinson, DPT, Ph.D. Temple University Neuroanatomy UMN cell bodies are in primary motor cortex Muscles of orofacial region Blood supply From “Corticobulbar Pathways” lecture (D102) W. Robinson, DPT, Ph.D. Temple University Neuroanatomy UMN axons project → corona radiata → internal capsule → CN V nucleus W. Robinson, DPT, Ph.D. Temple University Neuroanatomy CN V motor pathway UMN: 1 motor Precentral gyrus ◦ cortex → corona radiata → internal capsule → crus cerebri → terminates bilaterally at… LMN: motor nuclei of CN V → W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Trigeminal System - Clinical Considerations Precentral gyrus Central Nervous Peripheral System Pathologies – Since UMN – Trigeminal innervation to ganglion Tumors/lesions motor nucleus of Herpes zoster V is bilateral, (shingles) damage to one – Trauma side of Craniofacial; base corticobulbar of skull pathway will – Peripheral n. usually not From “Corticobulbar Pathways” lecture (D102) branchesW. Robinson, DPT, Ph.D. Temple University Neuroanatomy Trigeminal System - Clinical Considerations Precentral gyrus – Damage to UMNs on one Peripheral side of corticobulbar pathway will not Pathologies produce symptoms. – Trigeminal – Damage to LMNs can ganglion be detected due to Tumors/lesions ipsilateral loss of Herpes zoster muscle function (shingles) Mastication – Trauma – (chin deviation) Craniofacial; base – Muscle atrophy of skull Tensors – Peripheral n. – Veli palatini – Tympani branchesW. Robinson, DPT, Ph.D. Temple University Neuroanatomy Trigeminal Nerve Nuclei Motor Nuclei Sensory Nuclei Touch receptor in skin of forehead Trigeminal W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Cutaneous receptors convey sensations via differing pathways Sensory modalities – Proprioceptio n – Touch – Pressure – Vibration – Pain – Temperature From “Corticobulbar Pathways” lecture (D102) W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Sensory Trigeminal Pathways - The Basics Primary Secondary Tertiary /Mesencephalic Sensory receptors Modified from “Corticobulbar Pathways” lecture (D102) W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Pathway for the perception of orofacial pain W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Trigeminal Pain Pathway Trigeminothalamic tract midbrain pons medulla 1st order 2nd order neurons: 3rd order neurons: Spinal nucleus of CN V (conveys neurons: Receptors pain) Thalamus peripherally Trigeminothalamic tract Thalamocortical Adapted Synapse decussates to projects to… on… Pathways” lecture (D102) from “Corticobulbar projections W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Trigeminal Pain Pathway VPM neurons project to primary somatosensory cortex (located in the postcentral Thalamus VPL gyrus), via the posterior limb of the internal capsule. Rostral Ventral posterior Midbrainmesencephalic medial nucleus of thalamus (VPM) nucleus of V Trigeminothalamic tract trigeminal ganglion main sensory Pons nucleus of V spinal tract of V Medulla spinal nucleus of V Caudal Spinal cord From “Corticobulbar Pathways” lecture (D102) W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Thalamo-Cortical Projection Neurons in VPM send axons into the posterior limb of the internal capsule to ascend to the primary somatosensory cortex in the postcentral gyrus. The face is represented in the most lateral part of the postcentral gyrus. This is where sensation (pain) is perceived. W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Trigeminal nerve parasympathetic neurons None CN V does not contain any innate parasympath etic fibers but… W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Parasympathetic Supply to Head & Neck preganglionic postganglionic W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Trigeminal nerve does have a role in the parasympathetic pathways CN V does not contain any innate parasympathetic fibers But … branches of CN V provide routes to/from each of the parasympathetic ganglia: – Ciliary – Otic – Pterygopalatine – Submandibular W. Robinson, DPT, Ph.D. Temple University Neuroanatomy CN III parasympathetic fibers to intraocular muscles of globe Preganglionic parasympathetic fibers are within CN III Synapse in ciliary ganglion Postganglionic parasympathetics “hitchhike” on W. Robinson, DPT, Ph.D. Temple University Neuroanatomy CN VII parasympathetic fibers to lacrimal, submandibular & sublingual glands Preganglionic parasympathetic fibers are within CN VII Synapse in pterygopalatine ganglion Postganglionic parasympathetics Pterygopalatine Ganglion “hitchhike” on CN V2 W. Robinson, DPT, Ph.D. Temple University Neuroanatomy CN VII parasympathetic fibers to lacrimal, submandibular & sublingual Preganglionicglands parasympathetic fibers are within chorda tympani (CN VII) Synapse in submandibular ganglion Postganglionic parasympathetics “hitchhike” on lingual nerve (from V3) to W. Robinson, DPT, Ph.D. Temple University Neuroanatomy CN IX parasympathetic fibers to parotid gland Lesser Petrosal Nerve Preganglionic Otic parasympathetic Auriculotemporal Ganglion Tympanic branch of CN IX fibers are within nerve CN IX Synapse in otic ganglion Postganglionic parasympathetic s “hitchhike” on auriculotemporal W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Case study #1 A 51-year-old patient presents with the following signs and symptoms: – Significant hollowing of right temporal fossa & lateral cheek – Hyperacusis I’m experiencing – With open mouth: Déjà Vu Uvula: deviation to left Chin: deviation to right – Reflexes: Pupillary light, & accommodation: Normal bilaterally Gag & cough: Normal Jaw jerk: inconclusive Blink: Patient refused Localize the lesion W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Case study #1 A 51-year-old patient presents with the following signs and symptoms: mporalis Te – Hollowing of right temporal fossa & lateral cheek Skull fracture? Muscle atrophy? – Hyperacusis Loss of Stapedius? Tensor tympani? CN VII CN V – With open mouth: Uvula: deviation to CN X CN V left Loss of Levator veli palatini? Tensor veli palatini? Chin: deviation toLoss right of right lateral pterygoid – Reflexes: Pupillary light, & accommodation: Normal CNsbilaterally II & III intact Gag & cough: Normal CNs IX & X intact Jaw jerk: inconclusive Often the case; if normal, CN V intact; if clonus, think UMN lesion Blink: Patient refused With cooperation, would expect no response with stimulation of right cornea; direct and consensual response with stimulation of left cornea W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Jaw Jerk Reflex Testing for a jaw jerk reflex is done by gently tapping on the middle of the chin with the mouth slightly open, which normally causes contraction of muscles of mastication and jaw closing. However, may also be weak or absent. Both the afferent and the efferent limbs of the jaw jerk reflex are mediated by CN V: Afferent limb = mesencephalic nucleus With upper neurons, motor axons neuron division in mandibular lesions, of there V is a hyperactive orEfferent repeating limb =reflex (clonus). trigeminal With lower motor nucleus motor neuron lesions, neurons,the reflex axons is absent. in mandibular division of V From “Corticobulbar Pathways” lecture (D102) W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Jaw clonus is rhythmic, oscillatory contraction of jaw muscles W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Corneal (Blink) Reflex Normal: touch either cornea; both eyes close Afferent Limb: CN V1 – Cornea is without blood vessels, but is richly innervated – Sensation registers as pain, therefore axons project to spinal nucleus – Interneurons project bilaterally to CN VII motor nucleus Efferent Limb: CN VII → orbicularis oculi – Ipsilateral: “direct response” W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Case study #2 Following a dental procedure involving left mandibular nerve block, 29- year-old man complains of persistent W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Case study #2 Following a dental procedure involving left mandibular nerve block, 29- year-old man complains of persistent W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Case study #3 61-year-old female with a history of breast cancer with metastases to bone and liver She presents with diplopia (worse with The neurological examination revealed primary esotropia of the left eye and an obvious abduction deficit of the left eye on left gaze left lateral gaze) & numbness on the left side of her face (V1 & V2 W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Case study #3: Summary of findings 61-year-old female with a history of breast cancer with metastases to bone and liver. CNs affected: V1, V2, & VI The neurological examination revealed No other motor deficits primary esotropia of the left eye and an obvious abduction deficit of the left eye on left gaze detected: CNs V3 & VII ruled out Localize the lesion W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Case study #3 Axial MRI W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Case study #3 Axial MRI shows an asymmetric cavernous sinus, with dural thickening on the left. Post-contrast imaging shows increased enhancement of the left side of the W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Case study #3 lesion Coronal section Diagnosis: metastasis of breast carcinoma W. Robinson, DPT, Ph.D. Temple University Neuroanatomy W. Robinson, DPT, Ph.D. Temple University Neuroanatomy Looking for the perfect Valentine’s card? W. Robinson, DPT, Ph.D.