Cerebellum Physiology
•Download as PPTX, PDF•
135 likes•23,443 views
structure and function of cerebellum ,cerebellar disorders,MBBS lecture
Recommended
More Related Content
What's hot
What's hot (20)
Similar to Cerebellum Physiology
Similar to Cerebellum Physiology (20)
More from Raghu Veer
More from Raghu Veer (20)
Recently uploaded
Recently uploaded (20)
Cerebellum Physiology
- 1. Cerebellum Dr Raghuveer Choudhary Associate Professor Dept. of Physiology, Dr S.N.Medical College,Jodhpur (Rajasthan)
- 2. objective • • Outline of the afferent and efferent connections of the cerebellum. • • neuronal circuits in the cerebellum . • • the role of the cerebellum as regard control of motor function. • Cerebellar Dysfunctions
- 6. The Cerebellum • 11% of brain mass • Dorsal to the pons and medulla • Controls fine movement coordination • Balance and equilibrium • Muscle tone
- 7. Cerebellum • The cerebellum is vital to the control of rapid muscular activities such as running, typing, playing the piano, and talking. Loss of cerebellar function causes incoordination of these activities.
- 8. Balance
- 10. CEREBELLUM • The cerebellum is the third major division of the brain located in the posterior cranial fossa. • The cerebellum helps to control balance and posture, coordination of skilled voluntary movement, movement planning and the command to move.
- 11. Functions • Co-ordination of movement • The cortex initiates it and the cerebellum co-ordinates it.
- 12. cerebellum • centre of motor coordination • cerebellar disorders cause – incoordination or ataxia Damage to the cerebellum Causes a lack of co-ordination: Speaking Walking Tremour
- 13. Cerebellar Anatomy • Located dorsal to pons and medulla • In posterior fossa under tentorium cerebelli • Lobes – Floccular Nodular(small fluffy mass) – Anterior – Posterior
- 14. Figure 12.17b (b) Medulla oblongata Flocculonodular lobe Choroid plexus of fourth ventricle Posterior lobe Arbor vitae Cerebellar cortex Anterior lobe Cerebellar peduncles • Superior • Middle • Inferior
- 15. structure • Cerebellum is divided into 3 lobes by 2 transverse fissures – anterior lobe – posterior lobe – flocculonodular lobe
- 19. structure – anterior lobe (paleocerebellum) – large posterior lobe (neocerebellum) – flocculonodular lobe (archicerebellum is the oldest lobe)
- 20. Functional anatomy: From the functional point of view, the cerebellum is divided into 3 parts, it is organized along its longitudinal axis into 3 parts: Vestibulocerebellum/Archicerebellum Spinocerebellum/Paleocerebellum Cerebrocerebelum/neocerebellum
- 23. Functional and phylogenetic subdivision Regulation of muscle tone, coordination of skilled voluntary movement Planning of voluntary activity Maintenance of balance, control of eye movements Vestibulocerebellum/Archicerebellum Spinocerebellum/Paleocerebellum Cerebrocerebelum/neocerebellum Anterior Lobe Posterior Lobe Flocculo-Nodular Lobe (FN lobe) Primary fissure
- 25. 1- The vestibulocerebellum: which consists of the vermis nodulus and the flocculus on each side (flocculonodular lobe). This lobe is phylogenetically the oldest part of the cerebellum, it has vestibular connections, and is concerned with equilibrium. It is thus referred as archicerebellum.
- 26. 2- Spinocerebellum:(Paleocerebellum): It consists of the intermediate zone of the cerebellar hemisphere., This region receives proprioceptive input from the body and a copy of the motor plan from the motor cortex. It is concerned with coordination of movement.
- 28. 3- Cerebrocerebellum:(neocerebellum): It is the lateral portion of the cerebellar hemisphere. It is concerned with planning and programming of movements. It is connected mainly to the cerebral cortex.
- 33. Cerebellar Cortex Deep Cerebellar Nuclei: Dentate Interposed Fastigial
- 36. Dentate nucleus Cerebellar nuclei • The hemispheres contain four cerebellar nuclei
- 38. Globose nucleus Emboliform nucleus Interposed nuclei Cerebellar nuclei
- 40. Cerebellum • Cerebellar Cortex • Molecular Layer • Purkinje Cell Layer • Granular Layer • Corpus Medullare (Medullary Center) • Deep Cerebellar Nuclei • Fastigial Nuclei • Nucleus Interpositus • Emboliform Nucleus • Globose Nucleus • Dentate Nucleus
- 41. Microscopic Sections Outer Molecular layer Stellate cells, Basket cells Middle Purkinje cell layer Purkinje cells Inner Granular layer Granule cells, Golgi cells Cortex Mol Gr WM Molecular Granular
- 46. Major Cell Types •Granule cells •Purkinje cells •Golgi cells •Stellate cells •Basket cells Glutamate GABA GABA GABA GABA ***The Purkinje cell is the only output of the cerebellar cortex
- 48. Granule Cells Golgi Type II Cells GlomeruliMossy fibers
- 51. Golgi Cell
- 56. Purkinje cell Input from Inferior olive Input from other afferents Climbing fibre Mossy fibre Granule cells Deep nuclear cell Output excitationexcitation inhibition
- 57. Inputs: • Climbing fiber (“+”, excitatory, from inferior olive nucleus) • Mossy fiber (+, excitatory,from spinal cord & brain stem) Output: • Purkinje cell axon (“-”, inhibitory) Input and output of the cerebral cortex
- 58. • Purkinje cells & deep nuclear cells fire continuously • afferents excite the deep nuclear cells • Purkinje cells inhibit the deep nuclear cells
- 63. Simplified Cerebellar Circuitry Spinal Cord, Cerebral Cortex (via pontine nuclei), Vestibular System Cerebellar Cortex Inferior Olive Deep Cerebellar Nuclei Brainstem, thalamus, midbrain Mossy Fibers Climbing Fibers Spinal cord, Cerebral Cortex + - + INPUT
- 65. The Afferent Cerebellar Pathways Afferent Tracts Transmits Destination Dorsal spinocerebellar Unconscious kinesthetic & cutaneous afferents from trunk & leg Anterior lobe,pyramis,uvula & paramedian lobe via ipsilateral inferior cerebral peduncle Ventral Spinocerebellar Exteroceptive and proprioceptive fibres from body Vermis and anterior lobe via ipsilateral superior cerebral peduncle Vestibulocerebellar tract Vestibular impulse from labyrinth direct and via vestibular nuclei Flocculonodular lobe via ipsilateral inferior cerebral peduncle Cuneocerebellar tract Proprioceptive impulses, especially from arm,head and neck anterior lobe via ipsilateral inferior cerebral peduncle Tectocerebellar Auditory and visual impulses via inferior and superior colliculi Lobulus simplex ,declive & tuber via superior cerebral peduncle Corticopontocerebellar Impulses from motor and other parts of cerebral cortex via pontine nuclei All parts of cerebellar cortex except flocculonodular lobe via contralateral middle cerebellar peduncle Olivocerebellar Proprioceptive input from whole body via relay in inferior olive All parts of cerebellar cortex via contralateral inferior cerebral peduncle
- 79. Main Connections of the Vestibulocerebellum Floculonodular Lobe Vermis FASTIGIAL NUCLEUS VESTIBULAR NUCLEUS Vestibular Organ lower motor neuron LMN ARCHICEREBELLUM vestibulospinal tract MLF
- 80. Main Connections of the Neocerebellum CEREBRAL CORTEX THALAMUS Pontine Nucleus Lower motor neuron LMN DENTATE NUCLEUS POSTERIOR LOBE CEREBELLAR HEMISPHERE NEOCEREBELLUM Pyramidal tract
- 81. The Efferent Cerebellar Pathways Pathway Origin Destination Globose-emboliform-rubral Globose and emboliform nuclei To contralateral red nucleus, then via crossed rubrospinal tract to ipsilateral motor neurons in spinal cord Dentothalamic Dentate nucleus To contralateral ventrolateral nucleus of thalamus, then to contralateral motor cerebral cortex; corticospinal tract crosses midline and controls ipsilateral motor neurons in spinal cord Fastigial vestibular Fastigial nucleus Mainly to ipsilateral and to contralateral lateral vestibular nuclei; vestibulospinal tract to ipsilateral motor neurons in spinal cord Fastigial reticular Fastigial nucleus To neurons of reticular formation; reticulospinal tract to ipsilateral motor neurons to spinal cord
- 84. (1) CONTROL OF TONE & POSTURE: Spino- cerebellum Sup. & Inf. Colliculi Vesti. Nu. R.F. 1 2 4 5 6 7 o Mainly function of Spinocerebellum. CHANGE IN BODY POSTURE Proprioceptive from Body 2.Cuneo-cerebellar 1.Spino-cerebellar (dor. & Vent.) REFLEX CORRECTION OF MUSCLE TONE EASY MAINTANENCE OF NEW POSTURE 3.Tecto-cerebellar (Visual & Auditory) 4.Cereb.-vestibular 5.Cereb.-reticular 6.Vestibulo-spinal 7.Reticulo-spinal A.H.C. Functions of the cerebellum
- 88. (2) CONTROL OF EQUILIBRIUM: o Mainly function of Vestibulocerebellum. Vestibulo- cerebellum Vestibular Apparatus V. N. 1 1 2 3 CHANGE IN HEAD POSITION / ACCELARATION Labyrinthine Afferents 1.Vestibulo-cerebellar REFLEX CORRECTION OF MUSCLE TONE A.H.C. MAINTANENCE OF BODY EQUILIBRIUM 2.Cereb.-vestibular 3.Vestibulo-spinal Function of the cerebellum
- 90. Main Connections of the Vestibulocerebellum Floculonodular Lobe Vermis FASTIGIAL NUCLEUS VESTIBULAR NUCLEUS Vestibular Organ lower motor neuron LMN ARCHICEREBELLUM vestibulospinal tract MLF
- 92. Main Connections of the Paleocerebellum • RED NUCLEUSRED NUCLEUS NUCLEUS INTERPOSITUS ANTERIOR LOBE PARAVERMAL ZONE PALEOCEREBELLUM Inferior Olivry Nucleus Lower motor neuron SPINAL CORD Rubro spinal tract spinocerebellar tract
- 96. Functions of the cerebellum (3) CONTROL OF VOLUNTARY MOVEMENT: • Act as a “comparator of a servo mechanism” • Cerebellum receives two types of information – intended plan of movement (direct information from the motor cortex) – what actual movements result (feedback from periphery) • These two are compared: an error is calculated • Corrective output signals goes to – motor cortex via thalamus – brain stem nuclei and then down to the anterior horn cell through extrapyramidal tracts
- 97. Functions of cerebellum • planning of movements • timing & sequencing of movements • particularly during rapid movments such as during walking, running • from the peripheral feedback & motor cortical impulses, cerebellum calculates when does a movement should begin and stop
- 99. • ‘Prevention of overshoot’ – Soon after a movement has been initiated – cerebellum send signals to stop the movement at the intended point (otherwise overshooting occurs) • Ballistic movements – rapid movements of the body, eg. finger movements during typing, rapid eye movements (saccadic eye movements) – movements are so rapid it is difficult to decide on feedback – therefore the movement is preplanned
- 100. planning of movements • mainly performed by lateral zones • sequencing & timing – lateral zones communicate with premotor areas, sensory cortex & basal ganglia to receive the plan – next sequential movement is planned – predicting the timings of each movement
- 101. Cerebellum • The cerebellum can be permanently damaged by trauma or stroke or temporarily affected by drugs such as alcohol. • These alterations can produce ataxia – a disturbance in balance.
- 103. Damage to the cerebellum • The cerebellum can be permanently damaged by trauma or stroke or temporarily affected by drugs such as alcohol. • These alterations can produce ataxia – a disturbance in balance. Causes a lack of co-ordination: Speaking Walking Tremor
- 110. Are usually vascular, maybe traumatic or tumour. Manifestations of unilateral cerebellar lesions : 1-ipsilateral incoordination of (U.L) arm = intention tremors : it is a terminal tremors at the end of movement as in touching nose or button the shirt. 2-Or ipsilateral cerebellar ataxia affects (L.L.) leg, causing wide-based unsteady gait. Cerebellar Lesions
- 112. Cerebellar Lesions • Manifestations of bilateral cerebellar lesions (caused by alcoholic intoxication, hypothyrodism, cerebellar degeneration & multiple sclerosis) : • • 1-dysarthria : slowness & slurring of speech. 2-Incoordination of both arms.= intention tremors. 3-Cerebellar ataxia : intermittent jerky movements or staggering , wide-based, unsteady gait. 4-Nystagmus : is a very common feature of multiple sclerosis. It is due to impairment coordination of eye movements /so, incoordination of eye movements occurs and eyes exhibit a to-and-fro motion. • Combination of nystagmus+ dysarthria + intention tremors constitutes Charcot’s triad, which is highly diagnostic of the disease.
- 116. Refers to loss of balance, characterized by gait and trunk dystaxia. Cerebellar Dysfunction Disequilibrium
- 117. Is a loss of coordinated muscle activity and includes: Dysarthria is slurred or scanning speech. Dystaxia • is a lack of coordination in the execution of voluntary movement (e.g., gait, trunk, leg, and arm dystaxia). Cerebellar Dysfunction Dyssynergia
- 118. Cerebellar Dysfunction Dyssynergia Dysmetria • Is the inability to arrest muscular movement at the desired point (past pointing). Intention tremor • Occurs during a voluntary movement (a type of dysmetria).
- 119. Cerebellar Dysfunction Dyssynergia Dysdiadochokinesia • is the inability to perform rapid alternating movements (rapid sup- pination and pronation of the hands
- 120. Cerebellar Dysfunction Dyssynergia Nystagmus • is a form of dystaxia of eye movements (ocular dysmetria).
- 121. Cerebellar Dysfunction Dyssynergia Nystagmus • is a form of dystaxia of eye movements (ocular dysmetria).
- 122. Cerebellar Dysfunction Dyssynergia Decomposition of movement (“by-the-numbers" phenomenon) consists of breaking down a smooth muscle act into a number of jerk awkward component parts.
- 123. Cerebellar Lesions 1. Anterior vermis syndrome 2. Posterior vermis syndrome
- 124. Cerebellar Lesions Anterior vermis syndrome • involves the leg region of the anterior lobe. • results from atrophy of the rostral vermis, most commonly caused by alcohol abuse. • results in gait, trunk, and leg dystaxia. • *dystaxia- difficulty controlling voluntary mvts
- 125. Cerebellar Lesions Posterior vermis syndrome • involves the flocculonodular lobe. • is usually the result of brain tumors in children. mostly medulloblastomas • results in truncal dystaxia.