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Cerebellum Anatomy and Physiology

Clinical anatomy and physiology or cerebellum

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Cerebellum Anatomy and Physiology

  1. 1. CEREBELLUM Dr PS Deb MD, DM (Neuro) GNRC Hospitals Guwahati, Assam, India
  2. 2. SCHEMATIC REPRESENTATION OF THE MAJOR ANATOMICAL SUBDIVISIONS OF THE CEREBELLUM.
  3. 3. PHYLOGENETIC ORGANIZATION Spinocerebellum Pontocerebellum Vestibulocerebellum
  4. 4. DEVELOPMENT OF CEREBELLUM Archicerebellum (nodulus) Archicerebellum (flocculus) Paleocerebellum Neocerebellum
  5. 5. FUNCTIONAL ORGANIZATION OF CEREBELLUM
  6. 6. FUNCTIONAL AND PHYLOGENETIC ROLE Phylogenetic denomination Anatomical parts Role Vestibulocerebellu m (Archicerebellum) Flocculonodular lobe (+ adjacent vermis) Regulates balance and eye movements. Spinocerebellum (Paleocerebellum) Vermis and intermediate parts of the hemispheres ("paravermis") regulates body & limb movements. The spino cerebellum is able to elaborate proprioceptive input in order to anticipate the future position of a body part during the course of a movement. Cerebrocerebellum (Neocerebellum) Middle portion of the vermis & Lateral parts of the hemispheres involved in planning & initiation of movement.It has purely cognitive functions as well.
  7. 7. CEREBELLAR NUCLEUS Dentate n. Emboliform n. Globose n. Fastigial n.
  8. 8. FUNCTION OF CEREBELLAR NUCLEUS  The fastigial nucleus assists stance & gait & controls muscles only in the modes of sitting,standing & walking.  The nucleus interposed assists segmental reflexes & speeds the initiation of movement triggered by somatosensory cues.  The dentate nucleus assists in tasks requiring fine dextirity.
  9. 9. MOTOR MODULATION BY THE CEREBELLUM
  10. 10. INPUT OF CEREBELLUM
  11. 11. CEREBELLAR OUTPUT
  12. 12. VESTIBULOCEREBELLUM
  13. 13. THE SPINOCEREBELLUM CONTAINS TWO SOMATOTOPIC NEURAL MAPS OF THE BODY
  14. 14. NEOCEREBELLUM
  15. 15. NEURONAL CITCUITS OF CEREBELLUM
  16. 16. CEREBELLAR PATHWAY
  17. 17. Peduncle Description SUPERIOR some afferent fibers from the anterior spinocerebellar pass to the anterior cerebellar lobe via this peduncle. Thus, the superior cerebellar peduncle is the major output pathway of the cerebellum. Most of the efferent fibers originate within the dentate nu.which in turn project to various midbrain structures including the red nucleus, the ventral lat./ventral ant. nucleus of the thalamus, and the medulla. The dentatorubrothalamo cortical& cerebellothalamocortical pathways are two major pathways that pass through this peduncle and are important in motor planning. MIDDLE This is composed entirely of afferent fibers originating within the pontine nuclei as part of the massive corticoponto cerebellar tract.These fibers descend from the sensory and motor areas of the cerebral neocortex and make the middle cerebellar peduncle the largest of the three cerebellar peduncles. INFERIOR Proprioceptive information from the body is carried to the cerebellum via the dorsal spinocerebellar tract. This tract passes through the inferior cerebellar peduncle and synapses within the paleocerebellum. Vestibular information projects onto the archicerebellum.The climbing fibers of the inferior olive run through the inferior cerebellar peduncle.This peduncle also carries information from the Purkinje cells to the vestibular nuclei in the dorsal brainstem located at the junction between the pons and medulla
  18. 18. Tracts or fiber bundles Distribution Inferior cerebellar peduncle Afferent paths Olivocerebellar tract Lateral hemispheres and cerebellar nucleus Paraolivocerebellar tract Vermis, paravermis. and cerebellar nucleus Vestibulocerebellar tract Fastigial nucleus, flocculonodular lobe, and uvula Reticulocerebellar tract Spinal region of cerebellar vermis Posterior spinocerebellar tract Hind limb region of cerebellar cortex Trigeminocerebellar tract Dentate and emboliform nucleus Cuneocerebellar tract Forelimb and upper trunk region of cerebellar cortex Anterior exterior arcuate fibers Flocculus Arcuatocerebellar fibers (striae medullares) Flocculus Efferent paths Cerebellovestibular tract Vestibular nucleus Cerebelloreticular tract Pontine and medullary reticular nucleus CEREBELLAR CONNECTIONS--
  19. 19. Middle cerebellar peduncle Afferent paths Pontocerebellar tract Neocerebellar cortex Superior cerebellar peduncle Afferent paths Anterior spinocerebellar tract Hind limb region of cerebellar cortex Tectocerebellar tract Intermediate vermis and lobulus simplex Trigeminocerebellar tract Efferent paths Dentatorubral fibers Red nucleus Dentatothalamic fibers Ventral intermediate (VI) and ventral anterior (VA) nucleus of thalamus Fastigioreticular fibers Reticular nucleus of midbrain, pons, and medulla oblongata CONT.
  20. 20. Afferent connection
  21. 21. MAIN CONNECTIONS OF THE VESTIBULOCEREBELLUM Floculonodular Lobe Vermis FASTIGIAL NUCLEUS VESTIBULAR NUCLEUS Vestibular Organ lower motor neuron LMN ARCHICEREBELLUM vestibulospinal tract MLF
  22. 22.  RED NUCLEUS MAIN CONNECTIONS OF THE PALEOCEREBELLUM RED NUCLEUS NUCLEUS INTERPOSITU S ANTERIOR LOBE PARAVERMA L ZONE PALEOCEREBELLUM Inferior Olivry Nucleus Lower motor neuron SPINAL CORD Rubro spinal tract spinocerebellar tract
  23. 23. MAIN CONNECTIONS OF THE NEOCEREBELLUM CEREBRAL CORTEX THALAMUS Pontine Nucleus Lower motor neuron LMN DENTATE NUCLEUS POSTERIOR LOBE CEREBELLAR HEMISPHERE NEOCEREBELLUM Pyramidal tract
  24. 24. CEREBELLUM AND AUTOMATIC MOTOR CONTROL CEREBELLU M MOTOR CORTEX RED NUCLEUS VESTIBULA R NUCLEUS RETICULAR FORMATION LOWER MOTOR NEURON Proprioceptors
  25. 25.  Corticonuclear Connections  A zone ---------- fastigial nucleus  medial vestibular nucleus  B zone ---------- lateral vestibular nucleus  C1, C3 zone --- emboliform nucleus  C2 ---------------- globose nucleus  D1 ---------------- parvocellular portion of dentate nucleus  D2 ---------------- magnocellular portion of dentate nucleus VOOGD ORIGINALLY DESCRIBED 4 ZONES, FROM MEDIAL TO LATERAL--
  26. 26. 1. vermis 2. paravermal region 3. cerebella hemisphere 4. nodulus 5. flocculus 6. fastigial nucleus 7. globose nucleus 8. emboliform nucleus 9. dentate nucleus 10. medial vestibular nucleus 11. lateral vestibular nucleus
  27. 27.  The inferior olivary nucleus or inferior olive comprises 3 major divisions –  the principal olive (PO),  the dorsal accessory olive (DAO) and  the medial accessory olive (MAO).  Different divisions of the olive project to different cortical zones. The inferior olive is the only source of climbing fibre inputs to the cerebellum. Inputs from all other sources are as mossy fibres.
  28. 28. Olivocerebellar Connections  Caudal portion of  medial and dorsal accessory olivary nucleus  ----------------- vermis of cerebellar cortex (A and B)  fastigial nucleus  vestibular nucleus  Rostral portion of  medial and dorsal accessory olivary nucleus  ----------------- paravermal region (C1, C2, C3)  nucleus interpositus  Principal Inferior Olivary Nucleus  ----------------- cerebellar hemisphere (D1, D2)  dentate nucleus
  29. 29. Caudal portion Rostral portion Principal inferior olivary nucleus medial and dorsal accessory olivary nucleus
  30. 30.  The posterior inferior cerebellar artery (PICA): supplies-  Lat.medullary tegmentum,  inferior cerebellar peduncle  The ipsilat.portion of the inferior vermis &  the inferior surface of the cerebellar hemisphere.  The medial br. of the PICA supplies the medial cerebellum & the dorsolat. Medulla oblongata.  The lateral br.supplies the inferoposterolat. aspect of the cerebellum. VASCULAR SUPPLY OF THE CEREBELLUM:
  31. 31. CEREBELLAR CIRCULATION
  32. 32.  Maintenance of Equilibrium - balance, posture, eye movement  Coordination of half-automatic movement of walking and posture maintenace - posture, gait  Adjustment of Muscle Tone  Motor Leaning – Motor Skills  Cognitive Function CEREBELLUM:FUNCTIONS
  33. 33. ARCHICEREBELUM  Floculonodular lobe- Vestibulocerebelum  Function:  Maintenance of equilibrium  Suppress Vestibulo Ocular Reflex  Muscle tone in relation to head posture  Animal ablation  Disorder of equilibrium  Positional nystagmus  Human: Meduloblastoma  Trunkal ataxia  Vestibular nystagmus (fast component towards the side of lesion)  Positional nystagmus does not fatigue  Vertigo 22August2013
  34. 34. PALLEO-CEREBELUM  Anterior lobe + Vermis  Afferent:  Spinocerebellar tract  Spino-> olivo->cerebellar  Spino -> reticulo -> cerebellar  Efferent  Festigio -> vestibulo -> spinal  Festigio -> Reticulo -> Spinal  Function  Tone control  Posture of axial muscle  Equilibrium and locomotion  Animal ablation  Increased lengthening and shortening  Increased tendon reflex  Exagerated postural reflex (positive supporting reflex)  Human  Alcoholic degeneration  Cerebellar degeneration  Gait ataxia  Rarely mild hypotonia, dysmetria and dysarthria 22August2013
  35. 35. NEOCEREBELUM  Ablation in Dog and Cat inconstant result  Monkey ablation  Hypotonia  Clumsiness of ipsilateral limb  Dentate nucleus ablation -> more enduring effect intension tremor 22August2013
  36. 36. CEREBELLAR ZONES 1. Vermis zone: control posture, tone, locomotion, equilibrium i. Vestibular connection project to festigial nucleus ii. Control position of the head in relation to trunk and extraocular movments 2. Intermediate zone i. Affrent- a. proprioceptive from limb b. Sensorimotor cortex c. Collateral from corticospinal tract ii. Efferent globos and embodiform nucleus ->VL thalamus to motor cortex iii. Function: Regulation of movment via sensory feedback from the corticospinal muscle a. Control velocity, force, pattern of movement 22August2013
  37. 37. CEREBELLAR ZONES: LATERAL  Afferent: motor and sensory association cortex  Efferent: Dantate -> thalamus -> motor cortex (open loop)  Function: Programing of movement before initiation  Animal: coordination of ipsilateral movment  Human: Hypotonia- flabby muscle, abnormal posture (slopping of shoulder) increased excursion of outstretched hand tapping. Hyperflexibility of joint, pendular reflex knee  Cerebellum control separately the activity of alpha and gamma motor neuron  Reduced fusimotor activity from abnormal long loop reflex through precentral cortex 22August2013
  38. 38. CEREBELLAR DYSFUNCTION 1. Ataxia: Limb, gait and speech 2. Speech: Scanning 3. Tremor: Postural, intention, limb, trunk and head 4. Tone: Hypotonia -> Hyperextensibility, pendular knee jerk, rebound phenomenon 5. Voluntary movement: Dysmetria, dysynergia, disdidokokinesia 6. Gait: ataxic, truncal ataxia 7. Head tilt 8. Postural abnormality: due to unequal hypotonia of truncal muscle -> scoliosis, elevation or depression of shoulder, pelvic tilt 22August2013
  39. 39. VOLUNTARY MOVEMENT ABNORMALITY  Gorden Holms : Rate, range and force  Dyssynergia: Disruption of the normal smooth control of movement provided by gradual contraction of synergic muscle and relaxation of their antagonist  Voluntary movement- longer to start and longer to stop  Prolongation of interval between the command and triphasic agonist- antagonist and motor sequence  Agonist burst may be too long or short or continue into the antagonist burst -> dysmetria and dysenergia  Rebound phenomenon (abnormal check reflex)  Dysdiadokokinesia  Decomposition of movement  Scanning speech  Cogwheel eye moevment 22August2013
  40. 40. VOLUNTARY MOVEMENT ABNORMALITY  Dysmetria  Inability of the sensorimotor apparatus to measure distance in the course of movement  Hypometria and hypermetria of the limb and eye  Tremor : Postural and intention  Ataxia of gait: falling towards the side of lesion  Nystagmus:  Gaze paretic (evoked) deviation  Downbeat  Rebound  Sustained horizontal  Opsoclonus  Skew deviation  Weakness, faitibability and loss of associted movement 22August2013
  41. 41. THANKS

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