Nervous System

Physiology of vision

*Read foundation 1 notes Visual system Eye image formation & phototransduction Visual pathway tranmission of nerve impulses Visual cortex occipital lobe of cerebral cortex primary visual receiving area: sides of the calcarine fissure visual processing & perception occurs here Stimulus Light visible portion of the electromagnetic spectrum Sensory organ Eye optical instrument for focusing of…

Hearing & Equilibrium

*Read foundation 1 notes. Hearing: Organ of hearing organ of Corti Sensory receptor cochlea duct nerve cochlear nerve Equilibrium: Dancing with music dynamic equilibrium Organ of equilibrium dynamic: crista ampularis (hair cells + cupula) of the semicircular canals vestibular nerve static: maculae Common characteristics – receptor for hearing & equilibrium Hair cells bathed in endolymph…

Epilepsy

Definitions: Seizures occasional, sudden, rapid and local discharges of gray matter Epilepsy brain disorder characterised by periodic, unpredictable occurrence of seizures Seizures Transient changes of behaviour due to disordered, synchronous  and rhythmic firing at high frequency of groups of neurons from the cerebral cortex When seizure activity is initiated at local focus (cortex, hippocampus, thalamus)…

Control of posture & postural reflexes

Functions of posture Static postural reflexes maintenance of the body in an upright, balanced position Phasic postural reflexes provision of a stable background for voluntary activity Equilibrium: maintenance of a normal posture with good alignment Posture serves 3 main behavioural functions: Antigravity (STATIC) support head and body against gravity Alignment with centre of gravity (STATIC)…

Upper motor neuron & Lower motor neuron lesions

Definitions Upper motor neuron Corticospinal neuron Corticonuclear neuron Cerebral cortex (pyramidal tract) –> Precentral gyrus (motor strip) → internal capsule (posterior limb) → brainstem → spinal cord 85% cross to opposite side Upper motor neuron lesions Interruption of the corticospinal and corticonuclear tract along its course _____________________________________________________________________ Lower motor neuron Neurons from the brain stem…

Coordination of movement

Types of movements Unintentional – involuntary Intentional – voluntary Purpose of movements Protection/maintenance of posture To execute a voluntary movement in response to a thought/ idea or external stimulus [ from eyes, ears, touch, etc] Posture provides background for movement Movement starts with one posture and ends with another Coordination before and after movement Initiation…

Cerebrovascular disorders

Cerebrovascular accident (Stroke) Described by the side of the brain affected not the side of the clinical signs Eg. left cerebral infarct leads to right hemiparesis and dysphasia Types of stroke Infarction embolic hypotensive Haemorrhage aneurysm _____________________________________________________________________ Revision of basic anatomy of the brain Vascular supply of the brain Anterior from common carotids internal carotids…

MMS: ANS Physiology

1) Degenerative diseases of the nervous system associated with autonomic failure – Shy-Dragger syndrome Exercise 1: Orthostatic hypotension was 1st described by Shy & Dragger, and was termed ‘Shy-Dragger syndrome’. Study the organisation of the autonomic nervous system and work out which division (sympathetic/parasympathetic) is affected in the clinical problems described by Shy & Dragger….

Ocular movements & visual reflexes

Muscles of the orbit Extraocular 4 rectus Superior rectus oculomotor nerve Inferior rectus oculomotor nerve Medial rectus oculomotor nerve Lateral rectus abducen nerve 2 oblique Superior oblique Inferior oblique Levator Palpebrae Superioris (LPS) Smooth muscles Superior tarsal Inferior tarsal Orbitalis Intraocular Sphincter pupillae Dilator pupillae Ciliaris Bony orbit of the eye Superior frontal bone Inferior…

Middle Ear

General features of the ear 3 parts of the ear: External ear involved in hearing Anatomy: auricle: funnel shaped, elastic cartillage 3 parts: helix concha lobule external auditory meatus 2.5cm curved tube Outer 1/3: cartilage Inner 2/3: Bony (temporal bone) Modified sweat glands –> secrete cerumen prevents drying protects from insects Blood supply posterior artery…