Cranial nerves . • Exit: Where does the CN exit the CNS? And through which foramen in the cranium? • Func+on: Where does the CN aach? Muscle, gland, …? • Fiber type: Motor, sensory or both • Lesions: If you know the funcCon and fiber type, you know the lesion. CN I: Olfactory nerve Exit: Cribriform plate of ethmoid bone Func+on: OlfacCon (smell): the only sense that is NOT relayed by thalamus Fibers: Sensory Lesion: Can not smell CN II: Op6c Nerve Exits: OpCc canal (opCc canal: opCc nerve, ophthalmic artery) Func+on: - Vision - Afferent limb of pupillary light reflex Fibers: Sensory Lesions: f.eks Visual field defects: - Right monocular blindness - Bitemporal hemianopsia - LeS homonymous hemianopsia Pupillary light reflex pathway LETS DRAW Pupillary light reflex Visual field • Nasal reCna looks at the temporal eye field • Temporal reCna looks at the nasal eye field • Nasal reCna fibers decussate in the opCc chiasm DRAW WITH ME J Visual field defect - • Bitemporal hamianopsia Bitemporal hemianopia Right monocular hemianopia LeS homonymous hemianopia CN III: Oculomotor nerve Exit: SuKperior Orbital FKiKssure (III, IV, V1, VI) Func+on: - Eye movements: All except SO and LR - (KSO4KLR6K) 3 (Superior rectus, inferior rectus, medial rectus, inferior oblique, levator palpebrae) - Efferent limb of pupillary light reflex - PSANS fibers from EW nucleus causes pupillary constricCon Fibers: Motor (ParasympatheCc) Lesions: On an other slide. Lesion to CN III: Oculomotor Nerve 1. Pupil looks down and out (unopposed lateral rectus (CN VI) and superior oblique (CN IV)) 2. Ptosis (loss of innervaon of levator palpebrae) 3. “Blown pupil” (dilated pupil due to loss of PSANS fibers from EW nucleus of CN III) Anisocoria 1.Can be physiological Horners syndrome. CN IV: Trochlear nerve (Pulley) Exit: Exits the skull through SuKperior Orbital FKiKssure Func+on: Innervates superior oblique, which moves the eye DOWNK- (KSKO4K LR6K )3K K Fibers: Motor Lesion: Paent complains about walking stairs. Other important: The only nerve that exits from the dorsal aspect of the brainstem CN V: Trigeminal nerve ● Three branches • Exit • Funcon 1. V1: Ophthalmic nerve • Fiber 2. V2:Maxillary nerve 3. V3: Mandibular nerve • Lesion V1: Ophthalmic nerve Sensaon to the upper most par of Afferent limb of corneal (blink) reflex face V2: Maxillary nerve Sensaon to upper part of jaw V3: Maxillary Nerve Afferent AND efferent limbs of jaw jerk reflex Innervates muscles of mascaon V3: Maxillary Nerve SENSATION from anterior 2⁄3 of tonGue SENSATION from face CN VI: Abducens nerve Exits: SuKperior Orbital fKiKssure ( III, IV, V1, VI, ophthalmic vein) Func+on: Innervates lateral rectus- (KSO4KLR6K) 3 Fibers: Motor Lesions: Diplopia on lateral gaze CN VII: Facial Nerve Exit: IKnternal acousc meatus → facial canal (Gives of three branches)→ stylomastoid foramen-> Parod gland (Gives off five motor branches). Func+on: - Innervates stapedius muscle of inner ear - TASTE from anterior 2⁄3 of tongue - Innervaon to all glands, EXCEPT paroCd - Muscles of facial expression Fibers: - Motor - Taste, parasympatheCc fibers and sensory Lesions: UMN lesion and LMN lesions Posterior cranial fossa -> I​nternal acoustic meatus (Gives off three branches)→ facial canal→ stylomastoid foramen-> Parotid gland (Gives off five braches). Func6on of facial nerve Remember the branches of the facial nerve then it will be easier to remember the funcCon of it as well 7 branches of facial nerve. 1. Nerve to stapedius Innervates stapedius muscle of inner ear 2. Chorda Tympani TASTE from anterior 2⁄3 of tongue, submandibular and sublingual 3. Greater petrosal nerve Lacrimal gland, nasal gland 4. Motor branches: Muscles of facial expression and Muscles of facial expression - Temporal - Zygomac - Buccal - Mandibular - Cervical LETS DRAW AGAIN J CN VIII: Ves6bulocochlear nerve Exit: Internal acousCc meatus Func+on: Hearing Fibers: Sensory Lesion: I can’t hear you. Nerves in cerebelloponne angle: CN VII and CN VIII CN IX: Glossopharyngeal nerve Exit: jugular foramen (Jugularforamen=IX,X,XI) Func+on: - Afferent limb of gag reflex - Sensaon AKND taste from posterior 1⁄3 of tongue - Innervaon of paroCd gland Fibers: Sensory, ParasympatheCc CN X: Vagus nerve CN XI: Accessory nerve Exit: jugular foramen Func+on: Innervates trapezius (shrugging) and sternocleidomastoid (turns head to opposite side) Fibers: Motor Lesion: Inability to shrug shoulder and turn head. CN XII: Hypoglossal nerve Exit: Func+on: Muscles of the tongue Fibers: Motor Lesion: Tongue deviaon to iKpsilateral side “Lick your wounds” Ques6ons? • Pupillary light reflex • Corneal blink reflex • jaw jerk reflex • Gag reflex • Cough reflex Cranial nerve reflexes .