Presentation on theme: "CEREBELLUM AND BASAL GANGLIA HOPE AND JEN. CEREBELLUM Brief anatomy and functions Functions – DANISH Pathology."— Presentation transcript:
CEREBELLUM AND BASAL GANGLIA HOPE AND JEN
CEREBELLUM Brief anatomy and functions Functions – DANISH Pathology
BRIEF ANATOMY What do the lobes of the cerebellum do? Anterior cerebellum - unconscious proprioception Posterior cerebellum - fine motor control Flocculonodular - head & eye movements
FUNCTIONS OF THE CEREBELLUM Functions of the cerebellum: Maintenance of balance Posture and muscle tone Co-ordination Eye movements Planning movements Learning of motor skills. IMPORTANT: PROPRIOCEPTION Recieves input from spinocerebellar tract RECAP from week 1 block 3:
BLOOD SUPPLY Which 3 arteries supply the cerebellum? AICA – anterior inferior cerebellar artery (basilar) PICA – posterior inferior cerebellar artery (vertebral) SCA – superior cerebellar artery (basilar) NB LEARN YOUR CIRCLE OF WILLIS
DAMAGE TO CEREBELLUM Causes DANISH Areas damaged
WHAT COULD CAUSE DAMAGE TO THE CEREBELLUM? Tumours Strokes Degeneration Haemorrhage Trauma Alcohol Hereditory disorders Viruses
DANISH Clinical features of cerebellar disease Dysdiadokinesia Ataxia Nystagmus Intention tremor Scanning dysarthria Hypotonia (and heel-shin test) NB IPSILATERAL SYMPTOMS
DAMAGE TO THE CEREBELLUM: What do the lobes of the cerebellum do? Anterior cerebellum - unconscious proprioception Posterior cerebellum - fine motor control Flocculonodular - head & eye movements REMEMBER THIS? What could cause damage?Effects of damage Flocculonodular lobeDizziness, nausea, vomiting and nystagmus. Central vermal region(Tumour in 4th Ventricle)Midline lesions result in truncal ataxia, limb co- ordination can be ok Anterior lobe(alcoholic damage)Damage affects lower limbs - ataxic wide-based gait No heel toe walking or heel shin stroking with eyes open Posterior lobe (most of the cerebellum) Dysdiadochokinesia (inability to carry out rapid repeating movement) Dysarthria Dysmetria (inability to calculate trajectory) Tremor (intentional) Wide-based unsteady gait Linguistic incoordination - Grammar and syntax misuse
IMPORTANT CONDITIONS TO REMEMBER: PICA syndrome (Wallenberg syndrome, Lateral Medullary Syndrome) – KNOW FOR EXAM Cause: Occlusion to PICA due to thrombosis or stroke. Symptoms: Ataxia, vertigo, nystagmus, facial pain, dysphagia, Horner’s syndrome. Loss of pain and temperature on contralateral side of the body and ipsilateral side of the face. Freidreichs Ataxia Most common inherited ataxia – onset in teens before 25 yo Cause: mutation in FRDA gene – reduced frataxin protein – tissues normally high in frataxin preferentially affected. Symptoms: above + muscle weakness. Outcome: Loss of ambulation at 25 – death in mid 30s.
ANY QUESTIONS? Next up… Basal Ganglia!
BASAL GANGLIA BRIEF anatomy Direct pathway Indirect pathway Do it yourself (Disorders)
ANATOMY Striatum = Caudate nucleus Putamen Pallidum = Globus pallidus internus (medius) Globus pallidus externus (lateralis) Substantia nigra pars reticula Lentiform nucleus = Putamen Globus pallidus internus Globus pallidus externus Subthalamic nucleus Substantia nigra pars compacta
Cortex Striatum Globus Pallidus Internus & SNPR Thalamus Ventral Anterior/L ateral Nucleus Normal activity Inhibits VLN Therefore removal causes activation of the VLN Activity Inhibits GPI Activity Activates striatum Direct Pathway = Promotes movement Activity Activates Cortex (Premotor) Substantia Nigra pars compacta activates striatum via D1 receptors Activates striatum Excitatory = glutaminergic Inhibitory = GABAergic Inhibition of the inhibitory GPI allows the VLN to activate cortex VISUAL LEARNERS: WORD LEARNERS SYMBOLIC LEARNERS
GABA AND GLUT Green= excitatory (go!) gluta-green-ergic (GABA is opposite)
Cortex Striatum Globus Pallidus Internus & SNPR Thalamus Ventral Anterior/L ateral Nucleus Activity Inhibits VLN Activity Inhibits GPE Activates striatum Indirect Pathway = Inhibits Movement Normally Activates Cortex (Premotor) Globus Pallidus Externus Subthalamic nucleus Normal Activity Inhibits STN therefore removal causes activation of STN Activity Activates GPI & SNPR SNPC inhibits striatum via D2 receptors Inhibits striatum Inhibiting the inhibitory GPE enables STN to activate GPI which inhibits the thalamus D2 WORD LEARNERS SYMBOLIC LEARNERS
Substantia nigra pars compacta promotes movement via dopaminergic signalling SNPC (Dopaminergic) Activates direct pathway Direct pathway normally activates movement Inhibits indirect pathway Indirect pathway normally inhibits movement SNPC: A summary. SNPC releases dopamine which acts on: D1 in direct pathway to promote movement by activating that pathway. D2 in indirect pathway to promote movement by inhibiting that pathway.
BUILD YOUR PATHWAYS SPLIT INTO TWO GROUPS AND MAKE UP THE PATHWAYS (WE WILL BE HERE TO HELP)
PATHOLOGY OF BASAL GANGLIA ConditionCausesWhere is affected Effects on basal ganglia pathways Main symptoms ParkinsonsIdiopathic/iatrogeni c SNPCInhibits direct pathway – to slow initiation of movement. TRAP HuntingtonsGeneticStriatumInhibits indirect pathway – to remove ability to suppress movements. Involuntary horeiform (writhing) movements + cognitive changes HemiballismusVascularSubthalamic nucleus Inhibits indirect pathway – to remove ability to suppress movements. Undesired flailing limbs (mainly proximal limb muscles) TRAP: Tremor (resting) Rigidity Akinesia Postural instability TRAP: Tremor (resting) Rigidity Akinesia Postural instability
THANKS FOR LISTENING EMAIL/FB US WITH ANY QUESTIONS YOU HAVE. H.POOLE@WARWICK.AC.UK J.D.WILLIAMS@WARWICK.AC.UK Special effects: Andy