Neuroanatomy Cranial Nerves PDF

Neuroanatomy Nick Hurst  Neurological anatomy and physiology Aims and To understand the structure of a nerve cell objective Be able to explain how information is transmitted To be able to explain the development of the nervous system Be abl...

Neuroanatomy Nick Hurst  Neurological anatomy and physiology Aims and To understand the structure of a nerve cell objective Be able to explain how information is transmitted To be able to explain the development of the nervous system Be able to explain the organisation of the nervous system Identify regions of the brain and spinal cord and their functions Investigate the central nervous system and peripheral nervous system and how they relate to medical conditions  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 III – Generally These Somatic Innervate Also Oculomotor, taken together nerves all have a role to motor neurones extraocula r muscles – eye pregangli onic parasymp IV – play in eye movement athetic neurones Trochlear, movement and innervate VI - Abducens Control the smooth extrinsic muscle of the muscles eye 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-pal 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-trochle 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- 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 V - Trigeminal (mastication) 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 VII - Facial Motor Lesion UMN) 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 = VIII - Lateralized to impaired side. Sensorial = Lateralized to Vestibulocohlear good ear. Normal = 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 IX – Lesion on the opposite side Glossopharyngeal , X - Vagus Vocal quality Gag reflex Taste – Posterior 1/3 of tongue (sugar, salt, vinegar) Glossopharyngeal nerve https://medical-dictionary.thefreedictionary.com/ ‘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/ Picture: https://br.pinterest.com/pin/537476536762145864/ Finally…… https://www.youtube.com/watch?v=uHK7IBlNCBw