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  • 1. Cerebellar Control of Movements
  • 2. Organization of Cerebellum
  • 3. Functional organization of cerebellum
  • 4.
  • 5. Input of Cerebellum
  • 6. Cerebellar Output
  • 7. Vestibulocerebellum
  • 8. Neocerebellum
  • 9. The spinocerebellum contains two somatotopic neural maps of the body
  • 10.
  • 11.
  • 12. Cerebellar Pathway
  • 13.
  • 14. Cerebellum:Anatomy,connections,&functions
    Dr.Rupjyoti Das
  • 15. The cerebellum (Latin: "little brain") is a region of the brain that plays an important role in the integration of sensory perception and motor control.
    The cerebellum is located in the inferior posterior portion of the head (the hindrain), directly dorsal to the pons, and inferior to the occipital lobe &
    separated from cerebrum by tentoriumcerebelli.
    Weight=150 gm
  • 16.
  • 17. On axial & coronal planes,a midline portion,thevermis, and two lateral portions, the cerebellarhemispheres,can be recognized.
    The vermis is developmetally older & receives mainly spinocerebellar afferents, whereas the hemispheres have more complex fibre connections.
  • 18. Schematic representation of the major anatomical subdivisions of the cerebellum.
  • 19. The cortex is convoluted into many folia.
    Three major transverse divisions (lobes) are recognized—
    The anterior lobe is most rostral,
    posterior lobe and flocculo-nodular lobe more caudally.
    These lobes are divided by the primary fissure and the posterolateral fissure, respectively.
    Larselldescribed 10 lobules (subdivisions of the lobes) that can be recognized in all animals. Lobules I-V are within anterior lobe, lobules VI-IX are in posterior lobe and lobule X comprises the floccular-nodular lobe.
  • 20. Spinocerebellum
    Pontocerebellum
    Vestibulocerebellum
  • 21. Because of its large number of tiny granule cells, the cerebellum contains more than 50% of all neurons in the brain, but it only takes up 10% of total brain volume.
    The cerebellum receives nearly 200 million input fibres.
  • 22. Anatomical division- :
    the anterior lobe (rostral to the "primary fissure"),
    the posterior lobe (dorsal to the "primary fissure") and
    the flocculonodular lobe,
    The first two can be further divided in a midline cerebellarvermisand lateral cerebellar hemispheres.
    The cerebellum can be divided according to three different criteria: gross anatomical, phyologenetical, and functional:
  • 23. Classification by Phylogenetic and OntogenicDevelopment :
    Archicerebellum
    Paleocerebllum
    Neocerebellum
    Classification by Afferent Connection
    Vestibulocerebellum
    Spinocerebellum
    Pontocerebellum
    Classification by Efferent Connection
    Vermis
    Paravermal Region
    Cerebellar Hemisphere
  • 24. From the phylogenetically oldest to the newest, the three parts are:
  • 25.
  • 26.
  • 27. During the early stages of embryonic development, the brain starts to form in three distinct segments:
    the prosencephalon,
    mesencephalon, and
    rhombencephalon.
    The rhombencephalon is the most caudal (toward the tail) segment of the embryonic brain.
    Development of cerebellum
  • 28. Archicerebellum
    (nodulus)
    Archicerebellum
    (flocculus)
    Paleocerebellum
    Neocerebellum
  • 29. Along the embryonic rhombencephalic segment develop eight swellings, called rhombomeres. The cerebellum arises from two rhombomeres located in the alar plate of the neural tube, a structure that eventually forms the brain and spinal cord.
    The specific rhombomeres from which the cerebellum forms are rhombomere 1 (Rh.1) caudally (near the tail) and the "isthmus" rostrally (near the front).
  • 30. The cerebellum is of archipalliarphylogenetic origin. The pallium is a term for gray matter that forms the cortex. The archipallium is the one of the most primitive brain regions. The circuits in the cerebellar cortex look similar across all classes of vertibrates, including fish, reptiles, birds, and mammals.
  • 31. Subdivision ofFlocculonodular Lobe
    NodulusFlocculus
    Subdivision of Anterior Lobe
    Vermis Hemisphere
    Lingula
    Central Lobule Ala Central Lobule
    postcentral fissure
    CulmenQuadriangular Lobule
    Cerebellum-External configuration
  • 32. Subdivision of Posterior Lobe
    Vermis Hemisphere
    Declive Simple Lobule
    postcentral fissure
    Folium Superior Semilunar Lobule
    horizontal fissure
    Inferior Semilunar Lobule
    Tuber
    Gracile Lobule
    prepyramidal fissure
    Pyramid Biventral Lobule
    secondary fissure
    Uvula Tonsil
  • 33.
  • 34. Grey matter of cerebellum:
    1.Cerebellar cortex.
    2.Cerebellar nuclei
    cytoarchitecture
  • 35.
  • 36. The cerebellar cortex consists of three layers on a core of white matter.
    1.Molecular layer
    Consists mainly of neuropil and is the site of synapses.
    Contains scanty neurons consisting of stellate and basket cells.
    2.Purkinje cell (Piriform) layer
    Single layer of neurons.
    Consists of large (25 micrometer) pear-shaped neurons .
    3.Granular cell layer
    Very small(7 micrometer) granular neurons.
    Very numerous – 3 to 7 million neurons per cubic mm.
    4.White matter – forms the core of the foliae.
  • 37. 1.Outer stellate layer(In molecular layer)
    2.Basket cells ( -do- )
    3.Purkinje cells.
    4.Granule cells. (In granule cell layer)
    5.Golgi cells ( -do- )
    Neurons of cerebellar cortex
  • 38.
  • 39. The white matter of the cerebellum is made up of intrinsic,afferent & efferent fibres.
    Incoming impulses to the cerebellum reach the dendrites and cell bodies of Purkinje cells.
    The afferent fibres form the greater part of the cerebellar white matter and on entering the cerebellum,segregate into one of three fibre systems: the climbing,mossy or multilayered.
  • 40.
  • 41. The climbing fibresare the terminal fibres of the olivocerebellar tracts & make multiple synaptic contacts with one Purkinje cell.
    The mossy fibresystem includes all other cerebellar afferent tracts.In contrast to the climbing fibre system the mossy fibre system is diffuse,having multiple branches;so a single mossy fibre may stimulate thousands of Purkinje cells through the granule cell.
  • 42. The multilayered fibresystem includes afferents to the cerebellum from the hypothalamus,raphe nuclei & locus ceruleus & projects into the cerebellar cortex & deep cerebellar nuclei.
  • 43. In striking contrast to the 100,000-plus inputs from parallel fibers, each Purkinje cell receives input from exactly one climbing fiber; but this single fiber "climbs" the dendrites of the Purkinje cell, winding around them and making a large number of synapses as it goes.
  • 44. 8. parallel fiber 9. inferior oliva nucleus 0. d l nuclei
    1. Purkinje cell
    2. granule cell
    3. basket cell
    4. Golgi cell
    5. stellate cell
    6. climbing fiber
    7. mossy fiber
    8. parallel fiber
    9. inferior olivary
    nucleus
    10. deep cerebellar
    nuclei
  • 45.
  • 46.
  • 47. The Purkinje cells are central neurons (everything else converges on them)
    They consist of=
    A large dendritic tree in the molecular layer, which  is elaborately branched and  fan-shaped (branches are all in one plane) and has dendritic spines at the  sites of synapses.
    A large cell body.
     An axon  which forms the efferent pathway from the cerebellum , and  sends collaterals in the granular layer.
    GABA is the main neurotransmitter.
     
  • 48. The Granule cells:
    Very numerous: 3-7 million / mm3
    Very small (7mm), closely packed neurons.
    Heterochromatic nuclei, scanty cytoplasm.
    Small dendritic tree in granule layer.
    An unmyelinated axon.
    Directed to molecular layer (centrifugal).
    *Splits in T-shape manner to form parallel fibre.
    Parallel fibers run longitudinally along folia
    Cross dendrites of many Purkinje cells.
    Have glutamate as neurotransmitter.
     
  • 49. Cerebellar Neurons are Stimulatory or Inhibitory to Purkinje Cells.
    Climbing fibres are strongly excitatory.
    Mossy fibres stimulate granule cells.
    Parallel fibres of granule cells stimulate several Purkinje cells simultaneously.
    Basket cells strongly inhibit Purkinje cells.
    Stellate cells inhibit Purkinje cell dendrites.
    Golgi Type II cells inhibit directly the mossy fibre input.
  • 50. Main neurotransmitter= L-glutamate.
    Afferents reaching Purkinje through
    (Mossy/Climbing fibres)
    :Excitatory.
    Purkinje cells =GABAergic.
    Golgi cells= -do-
    Stellate cells = -do-
    Basket cells = -do-
    Neurochemistry
  • 51. Embedded within the white matter—which is known as the arbor vitae (Tree of Life) in the cerebellum due to its branched, treelike appearance—are four deep cerebellar nuclei:
    From lateral to medial, they are the
    dentate,
    emboliform,
    globose, and fastigial.
  • 52.
  • 53. Dentate n.
    Emboliform n.
    Globose n.
    Fastigial n.
  • 54. These nuclei receive inhibitory (GABAergic) inputs from Purkinje cells in the cerebellar cortex and
    excitatory (glutamatergic) inputs from mossy fibre pathways.
    Most output fibers of the cerebellum originate from these nuclei.
  • 55. 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.
    Each nucleus controls a diff.type of movement as follows:
  • 56. The cerebellum follows the trend of "threes", with three major input and output peduncles (fiber bundles). These are
    the superior (brachium conjunctivum),
    middle (brachium pontis), and
    inferior (restiform body) cerebellar peduncles.
  • 57.
  • 58.
  • 59.
  • 60. Cerebellar connections--
  • 61. Cont.
  • 62.
  • 63. Afferent connection
  • 64. Main Connections of the Vestibulocerebellum
    Vestibular
    Organ
    Floculonodular
    Lobe
    Vermis
    VESTIBULAR NUCLEUS
    vestibulospinal tract
    MLF
    FASTIGIAL
    NUCLEUS
    lower motor neuron
    ARCHICEREBELLUM
    LMN
  • 65. Main Connections of the Paleocerebellum
    NUCLEUS INTERPOSITUS
    RED NUCLEUS
    RED NUCLEUS
    Rubro
    spinal tract
    ANTERIOR LOBE
    PARAVERMAL ZONE
    Inferior
    Olivry
    Nucleus
    PALEOCEREBELLUM
    Lower motor neuron
    SPINAL CORD
    spinocerebellar tract
  • 66. Main Connections of the Neocerebellum
    CEREBRAL CORTEX
    THALAMUS
    DENTATE
    NUCLEUS
    Pontine
    Nucleus
    POSTERIOR
    LOBE
    CEREBELLAR HEMISPHERE
    Pyramidal tract
    NEOCEREBELLUM
    Lower motor neuron
    LMN
  • 67. Cerebellum and Automatic Motor Control
    MOTOR CORTEX
    CEREBELLUM
    RED NUCLEUS
    VESTIBULAR NUCLEUS
    RETICULAR FORMATION
    LOWER MOTOR NEURON
    Proprioceptors
  • 68. 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--
  • 69. 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
  • 70. 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.
  • 71. 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
  • 72. Caudal portion
    Rostral portion
    Principal inferior olivary nucleus
    medial and dorsal accessory olivary nucleus
  • 73. Vascular supply of the cerebellum:
    The posterior inferior cerebellar artery (PICA): supplies-
    Lat.medullarytegmentum,
    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.
  • 74.
  • 75. The ant.inf.cerebellar artery (AICA) supplies-
    Ant.petrosal surface of the cerebellar hemisphere,
    Flocculus,
    Lower portion of the middle cerebellar peduncle &
    Lat.pontomedullarytegmentum
  • 76. The superior cerebellar artery (SCA) supplies-
    The upper surface of the cerebellar hemisphere,
    Ipsilat.portion of the superior vermis,
    Most of the dentate nucleus,
    Upper portion of the MCP,SCP & lat.pontinetegmentum.
  • 77. 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
  • 78. BALANCE
  • 79. MOTOR SKILLS
  • 80. 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
    28 October 2010
  • 81. 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
    28 October 2010
  • 82. Neocerebelum
    Ablation in Dog and Cat inconstant result
    Monkey ablation
    Hypotonia
    Clumsiness of ipsilateral limb
    Dentate nucleus ablation -> more enduring effect intension tremor
    28 October 2010
  • 83. Cerebellar zones
    Vermis zone: control posture, tone, locomotion, equilibrium
    Vestibular connection project to festigial nucleus
    Control position of the head in relation to trunk and extraocularmovments
    Intermediate zone
    Affrent-
    proprioceptive from limb
    Sensorimotor cortex
    Collateral from corticospinal tract
    Efferent globos and embodiform nucleus ->VL thalamus to motor cortex
    Function: Regulation of movment via sensory feedback from the corticospinal muscle
    Control velocity, force, pattern of movement
    28 October 2010
  • 84. 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 ipsilateralmovment
    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
    28 October 2010
  • 85. Cerebellar dysfunction
    Ataxia: Limb, gait and speech
    Speech: Scanning
    Tremor: Postural, intention, limb, trunk and head
    Tone: Hypotonia -> Hyperextensibility, pendular knee jerk, rebound phenomenon
    Voluntary movement: Dysmetria, dysynergia, disdidokokinesia
    Gait: ataxic, truncal ataxia
    Head tilt
    Postural abnormality: due to unequal hypotonia of truncal muscle -> scoliosis, elevation or depression of shoulder, pelvic tilt
    28 October 2010
  • 86. 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
    28 October 2010
  • 87. 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
    28 October 2010