Neuroanatomy Cranial Nerves.pdf

Picture: https://www.britannica.com/science/cranial-nerve Cranial Nerves  On Occasion Our Trusty Truck Acts Funny, Very Good Vehicle Any How I – Olfactory II – Optic III – Oculomotor IV – Trochlear V – Trigeminal VI – Abducens VII – Facial VIII –...

Picture: https://www.britannica.com/science/cranial-nerve Cranial Nerves  On Occasion Our Trusty Truck Acts Funny, Very Good Vehicle Any How I – Olfactory II – Optic III – Oculomotor IV – Trochlear V – Trigeminal VI – Abducens VII – Facial VIII – Vestibulochlear IX – Glossopharyngeal X – Vagus XI – Accessory XII - Hypoglossal  Some Say Marry Money But My Brother Says Big Brains Matter More Cranial I: Sensory Cranial II: Sensory Cranial III: Motor Cranial IV: Motor Cranial V: Both (sensory & motor) Cranial VI: Motor Cranial VII: Both (sensory & motor) Cranial VIII: Sensory Cranial IX: Both (sensory & motor) Cranial X: Both (sensory & motor) Cranial XI: Motor Cranial XII: Motor  I – Olfactory nerve Attached directly to forebrain Closely associated with Limbic system  II - Optic Attached directly to forebrain Impulses from the retina to the brain Visual field testing Colour vision test (Ishihara) Visual acuity (Snellen) Papillary response  Generally These nerves Somatic Innervate Also III – Oculomotor, taken together all have a role to play in eye motor neurones extraocular muscles – eye preganglionic parasympathe IV – Trochlear, movement movement tic neurones and innervate the extrinsic VI - Abducens muscles of the eye Control smooth muscle of the eye Oculomotor Nerve (III) Role: Innervates extrinsic eye muscles Raise eyelid Innervates intrinsic eye muscles – pupillary constriction and accommodation Cranial (Third) nerve palsy Uncommon Mortality and morbidity is dependant on the underlying cause Ie subarachnoid haemorrhage, meningitis, neoplasm Cause: Direct trauma Demyelinating disease (ie MS) Increased intracranial pressure Space-occupying lesion Spontaneous subarachnoid haemorrhage Microvascular disease (ie diabetes) Microvascular disease (ie giant cell arteritis) https://ebmnerd.com/cranial-nerve-3-palsy/ Trochlear nerve (IV) Role: Motor nerve Innervates single muscle – superior oblique muscle Lateral/inferior gaze Only cranial nerve to emerge from the dorsal aspect of the brain stem Single IV lesion – Rare – common cause trauma to orbit Signs of single IV lesion Diplopia due to weakness and downward and inward eye movement Compensate – tilting head away form affected side http://www.clinicalexams.co.uk/4th-cranial-nerve-tests-for-the-trochlear-nerve/ Abducen nerve (VI) Role: Motor nerve Movement of lateral rectus muscle Outwards (lateral) gaze Signs of single IV lesion Inability to look laterally Causes MS, pontine CVA https://www.neurologyneeds.com/neuroanatomy/cranial-nerves/nvi-abducens-nerve/ Combined III, IV and VI lesions CVA Tumours, Wernicke's encephalopathy, Aneurysms, MS, Myasthenia gravis, Meningitis, Muscular dystrophy, Myotonic dystrophy, Cavernous sinus thrombosis, GBS, Cranial arteritis, Trauma and orbital pathology.  Has a motor & sensory component: Motor - Muscles of chewing (mastication) V - Trigeminal Sensory - Facial sensation (split into 3) https://www.drugs.com/cg/trigeminal-neuralgia.html  Motor Assessment: Palpate Masseter & temporalis muscles Open mouth against resistance Sensory: Sharp & dull sensation in nerve distribution Reflex: Corneal reflex – Blink response to light touch (cotton, tissue) of cornea  Motor: Inspect nasolabial folds Can the patient raise their eyebrows, close the eyes tight or blow out the cheeks (forehead sparing = Upper Motor Lesion UMN) VII - Facial Sensory: Taste in the anterior 2/3 of the tongue. Usually ask about sense of taste or can be tested with sugar, salt, vinegar https://www.sciencedirect.com/topics/neuroscience/nerve-to-the-stapedius Bell’s Palsy  Hearing, balance & equilibrium: Simple tests of auditory acuity Weber’s test – tuning fork on top of head. Conduction = Lateralized to VIII - impaired side. Sensorial = Lateralized to good ear. Normal = Vestibulocohlear Mid-line Rinne’s test – Compare air conduction to bone conduction (in normal conditions air is better than bone conduction https://www.pinterest.com/pin/188377196886865106/  Generally assessed together and work together to control pharynx, larynx and swallow: Uvula elevation – Say “Ahhhh” If it moves to one side = X Lesion on the opposite side IX – Glossopharyngeal, X - Vagus Vocal quality Gag reflex Taste – Posterior 1/3 of tongue (sugar, salt, vinegar) Glossopharyngeal nerve https://medical-dictionary.thefreedictionary.com/glossopharyngeal+nerve ‘Wandering’ nerve Left and right asymmetry  Innervation of the sternocleidomastoid and trapezius muscles Ask the patient to shrug their shoulders against resistance XI - Accessory (trapezius) Ask the patient to turn head from side to side against resistance (sternocleidomastoid) Accessory nerve https://medical-dictionary.thefreedictionary.com/accessory+nerve  “Stick your tongue out and move it side to side” Inspect the tongue – Fasiculations, atrophy (lower motor neuron LMN) XII - Hypoglossal Deviation to one side usually indicates lesion on the side to which the tongue is deviated Hypoglossal nerve https://www.pinterest.com/pin/320670435941971784/ Picture: https://br.pinterest.com/pin/537476536762145864/