LECTURE 28- ANATOMY OF CEREBELLUM AND ITS CONNECTIONS Dr. Mohammad Rehan Asad.
Anatomy of cerebellum
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Transcript of Anatomy of cerebellum
CEREBELLUM
DR MANAH CHANDRA CHANGMAI
BY
GROSS ANATOMY OF CEREBELLUMLocation: The term cerebellum is from “latin
meaning” the little brain.It is a part of the hindbrain situated in the posterior cranial fossa.
It is also present behind the pons and medulla ablongata,seperated from two structures by the cavity of fourth ventricle.
It is covered by tentorium cerebelli and is connected to brain stem by three cerebellar peduncles.
In adults the weight ratio between cerebellum and cerebrum is 1:10,Infants 1:20
Consists of two laterally, large hemisphere which are united by midline vermis.
Cerebellar surface is divided by numerous curve transverse fissures giving it a laminated appearance
One conspicious fissure “horizontal fissure”extends around dorsolateral border of each hemisphere from middle cerebellar peduncle to vallecula,seperating superior and inferior surface
Horizontal fissure
Vermis
Hemisphere
Superior surface
Anatomy of cerebellum......contd.
The deepest fissure in the vermis is primary fissure, which curves ventrolaterally in the superior surface of the cerebellum to meet horizontal fissure.
Primary fissure divides the cerebellum into anterior and posterior lobe.
Primary fissure
Anterior lobe
Posterior lobe
Primary fissure
External surface of cerebellum
Horizontal fissure
verm
is
Primary fissure
Anterior
lobe
Posterior lobe
Hemisphere
External surface of cerebellum
Fourth ventricle
Arbor vitae cerebelliArbor
vitae •In latin “ tree of life” it is the white matter of the white matter of cerebellum.
•It is so called because of the tree like appearance.
•It brings sensory and motor sensation to and from cerebellum.
The cerebellum is connected toBrain stem by three peduncles
Superior cerebellar peduncle
Midbrain Middle cerebellar
peduncle
PonsInferior cerebellar peduncle
Medulla ablongata
Peduncles of the cerebellum
Vermis
Hemisphere
Parts of the cerebellum
LOBES OF CEREBELLUM
Divisions of lobes
Anatomical
Flocculonodular lobe
Anterior lobe
Posterior lobe
Anterior lobe
Posterior lobe
Flocculonodular lobe
Inferior surface
Superior surface
Anterior lobe
Posterior lobe
Functional(Evolutionary)
Paleocerebellum
Neocerebellum
Archicerebellum
Division of lobes…..contd.
Archi-cerebellum posterior lobe (Vestibular part) •It is formed of the flocculo-nodular lobe + associated fastigial nuclei, lying on inf. Surface in front of postero-lateral fissure. •Embryologically, it is the oldest part of cerebellum. •It receives afferent Fibres. From vestibular apparatus of internal ear Via vestibulo-cerebellar tracts. •It is concerned with equlibrium Neocerebellum
Archicerebellum
Paleocerebellum
It has connections with vestibular & reticular nuclei of brain stem through the inferior cerebellar peduncle.
Afferent vestibular Fibres. Pass from vestibular nuclei in pons & medulla to the cortex of ipsilateral flocculo-nodular lobe.
Efferent cortical (purkinje cell) Fibres. Project to fastigial nucleus, which projects to vestibular nuclei & reticular formation.
It affects the L.M.system bilaterally via descending vestibulo-spinal & reticulo-spinal tracts.
Archicerebellum …….contd.
Paleo-cerebellum (spinal part) : •it is formed of midline vermis + surrounding paravermis + globose & emboliform nuclei. •It receives afferent proprio-ceptive impulses from Ms.& tendons Via spino-cerebellar tracts (dorsal & ventral) mainly. •it sends efferents to red nucleus of midbrain. •it is concerned with muscle tone
Paleocerebellum
It is concerned with muscle tone & posture.
. Afferents spinal Fibres consist of dorsal & ventral spino-cerebellar tract from muscle, joint & cutaneous receptors to enter the cortex of ipsilateral vermis & para vermis Via inferior & superior cerebellar peduncles .
Efferents cortical fibres pass to globose & emboliform nuclei, then Via sup. C. peduncle to contra-lateral red nucleus of midbrain to give rise descending rubro-spinal tract.
Neo-cerebellum (cerebral part) •It is the remaining largest part of cerebellum. •It includes the most 2-cerebellar hemispheres + dendate nuclei. •It receives afferent impulses from the cerebral cortex+pons Via cerebro-ponto- cerebellar pathway. •it sends efferents to Ventro lateral nucleus of thalamus. •it controls voluntary movements (muscle coordination).
Neocerebellum
It is concerned with muscular coordination.
It receives afferents from cerebral cortex involved in planning of movement- to pontine nuclei ,cross to opposite side Via middle Cerebellar peduncle to end in lateral parts of cerebellum (cerebro-ponto-cerebellar tract).
Neo-cerebellar efferents project to dendate nucleus,which in turn projects to contra-lateral red nucleus & ventral lateral nucleus of thalamus ,then to motor cortex of frontal lobe, giving rise descending cortico-spinal & cortico-bulbar pathways. Efferents of dentate nucleus form a major part of superior C. peduncle.
Other types of Divisions
Afferent regions
— Spinocerebellum — Pontocerebellum
Efferent regions
— Vestibulocerebellum — Lateral Hemisphere
Ontogenic development
Archicerebellum Paleocerebllum Neocerebellum
Classification by Afferent Connection
Vestibulocerebellum Spinocerebellum Pontocerebellum
Classification by Efferent Connection
Vermis Paravermal Region Cerebellar Hemisphere
ArchicerebellumNodulusArchicerebellumflocculusPalaeocerebellum
Neocerebellum
Spinocerebellum
Pontocerebellum
Vestibulocerebellum
Classification by phylogenetic
Summary of classification
Cortex Medulla
Structure of the cerebellum
Vermis Hemisphere Nodulus Flocculus
Subdivision of Flocculonodular lobe
Vermis Hemisphere
Lingula
Central lobule Ala of the central lobule
Subdivision of Anterior lobe
Subdivision of lobes
Flocculus Nodulus
Lingula
Cent
ral l
obue
l
Ala of central lobule
Vermis Hemisphere
Declive Simple lobule
Postcentral fissure
Vermis Hemisphere
Folium Superior semilunar lobule
Vermis Hemisphere
Tuber Inferior semilunar lobule
Gracile lobule
Horizontal fissure
Posterior lobe
DecliveSimple lobule
folium
Supe
rior s
emilu
nar l
obul
e
Tuber
Inferior se
minular lobule
uvula
Vermis Hemisphere
Pyramid Biventral lobule
Uvula Tonsil
Ant lobe
Post lobe
Inferior surface
Ant lobe
Post lobe
Superior surface
Structure
Cerbellum consists of outer layer of grey matter known as cortex and inner layer of white matter known as medulla.
The medullary core is composed of incoming and outgoing fibres projecting to and from the cerebellar cortex.
Medullary core also contain the nucleuses of the cerebellum which are four in number.
Cortex Medulla Structure of cerebellum
Structure of cerebellar……contd.
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
CEREBELLUM cortex
• Cerebellar Cortex
• I. Molecular Layer
• Stellate Cell --- taurine (inhibitory)
• afferent: parallel fiber • efferent: Purkinje cell dendrite
• Basket Cell ---- GABA (inhibitory)• afferent: parallel fiber• efferent: Purkinje cell soma
• • Parallel Fiber• granule cell axon
• Purkinje Cell Dendrite
Cerebellum layers……contd.
• II. Purkinje Cell Layer
• Purkinje Cell • -- 15,000,000 in number• -- GABA (inhibitory)• afferent: parallel fiber • climbing fiber• stellate cell• basket cell • efferent: deep cortical nuclei
• Bergman’s glial cell
Purkinje cells
flaskshaped cell, single layered Dendrites -Molecular layer - profuse branching - dendritic spines Axon - synapse with deep cerebellar nucleus - basket & stellate cells - vestibular nuclei
Cerebellum layers……..contd.
• III. Granular Layer
• Granular Cell • -- 50,000,000,000 in number• -- glutamic acid (excitatory)• afferent: mossy fiber• efferent: Purkinje cell axon• basket cell, stellate
cell• Golgi cell
• Golgi Cell• -- GABA (inhibitory)• afferent: parallel fiber, mossy
fiber rosette• efferent: granule cell dendrite
Climbing fibres
- from inferior olivary complex- direct action on individual Purkinje cell- powerful , sharply localised
- Basket cells, stellate cells, Golgi cells act as inhibitory interneurons.
Mossy fibres
-from spinal cord / brain stem centres-indirect action on Purkinje cells via granule cells-diffuse
( thousands of Punkinje cells may be excited )
White matter of the cerebellum
Consists of three types of nerve fibres in the white matter
A. Axons of purkinje cells The only axons to leave cerebellar cortex to end in deep cerebellar nuclei specially dendate nucleus.
B. Mossy fibres They end in the granular layer.
C. Climbing fibres They end in the molecular layer
The internal circuity of cerebellum Donot leave the cerebellum,interconnect different regions of cerebellum. Some connect the same side. Some connect the two cerebellar hemisphere
The cerebellar efferent via middle cerebellar peduncle(MCP) and inferior cerebellar peduncle (ICP)
The cerebellar afferent via superior cerebellar peduncle(SCP) and from fastigial from inferior cerebellar peduncle(ICP)
White matter of cerebellum
Afferent pathways to cerebellar cortex excite Purkinje cells.
Basket, stellate and Golgi cells regulate Purkinje cell activity
Efferent pathways from the cerebellar cortex originate from Purkinje cells -
Intrinsic pathway
Intrinsic pathway
Cerebellar AFFERENT pathway
From cerebral cortexcortico-ponto-cerebellar fibrescerebro-olivo-cerebellar fibrescerebro- reticulo- cerebellar fibres
From spinal cordanterior spinocerebellar tractposterior spinocerebellar tractcuneocerebellar tract
From vestibular nucleusvestibulocerebellar tract [ flocculonodular lobe ]
From other areasred nucleus, tectum
Afferent pathway origin Destination via
Corticopontocerebellar Frontal,parietal, temporal, occipital
Pontine nuclei & mossy fibres to cerebellar cortex
Cerebroolivocerebellar INF olivary N & climb fibres to cerebellar cortex
Cerebroreticulocerebellar Sensorimotor areas
Reticular formation
Ant spinocerebellar Muscle spindles,tendons, joints
Mossy fibres to cerebellar cortex
Post spinocerebellar
Cuneocerebellar
Vestibular nerve Utricle, saccule,semicircular canals
Mossy fibres to cortex of FN node
others Red nuc, tectum cerebellar cortex
Cerebellar EFFERENT pathways
• Axons of Purkinje cells
synapse with the cerebellar nuclei.
• Axons of the neurones form the efferent pathways
Connect with
• Red nucleus
• Thalamus
• Vestibular nuclei
• Reticular formation
Histological structure of cerebellum
Molecular layer
Purkinje layer
Granular layer
Histology of the cerebellum…..contd
Cerebellar cortex…..contd.
• Synaptic Glomerulus
• Afferent terminals on granular layer
• Mossy Fiber Rosette • -- afferent fibers except• inferior olivary input• -- 2/3 of medullary center
• Granular Cell Dendrite • -- main afferent input
• Golgi Cell Axon • -- synapse on granule cell
dendrite• -- GABA (inhibitory)
• - Surrounded by Astrocyte
Foot Process
Cerebellar structure……Deep nuclei
• 1. fastigial • nucleus
• 2. globose • nucleus
• 3. emboliform • nucleus
• 4. dentate • nucleus
Dentate nucleus
Emboliform nucleus
Globose nucleus
Fastigial nucleusNucleus interpositus
Deep nucleuses of cerebellum
Fibres entering and leaving through cerebellar peduncles
Superior cerebellar peduncle
A. Fibres entering the cerebellum 1. Ventral spino-cerebellar tract 2. Rostral spino-cerebellar tract 3. Tecto-cerebellar fibres 4. Rubro-cerebellar fibres 5. Trigemino-cerebellar fibres 6. Hypothalamo-cerebellar fibres 7. Coerulo-cerebellar fibres
B. Fibres leaving the cerebellum 1. Cerebello-rubral fibres 2. Cerebello-thalamic fibres 3. Cerebello-reticular fibres 4. Cerebello-olivary fibres 5. Cerebello-nuclear fibres 6. Some fibres to hypothalamus and thalamus
Superior cerebellar peduncle
Middle cerebellar pedunclePontocerebellar fibres
Inferior cerebellar peduncle
A. Fibres entering cerebellum 1. Posterior spino cerebellar tract 2. Cuneo-cerebellar tract 3. Olivo-cerebellar fibres 4. Reticulo-cerebellar fibres 5. Vestibulo-cerebellar fibres 6. Anterior external arcuate fibres 7. Fibres of striae medullaries 8. Trigemino-cerebellar fibres
B. Fibres Leaving the cerebellum 1. Cerebello-olivary fibres 2. Cerebello-vestibular fibres 3. Cerebello spinal and cerebello reticular fibres
Middle cerebellar peduncle
Inferior cerebellar peduncle
Classification of cerebellum
• Classification by phylogenetic and Ontogenic development
• Archicerebellum• Paleocerebllum• Neocerebellum
• Classification by Afferent Connection
• Vestibulocerebellum• Spinocerebellum• Pontocerebellum
• Classification by Efferent Connection
• Vermis• Paravermal Region• Cerebellar Hemisphere
ArchicerebellumNodulus
ArchicerebellumflocculusPalaeocerebellum
Neocerebellum
Spinocerebellum
Pontocerebellum
Vestibulocerebellum
CT SCAN OF BRAIN WITH CEREBELLUM
MRI OF BRAIN WITH CEREBELLUM
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
Functions of cerebellum
Balance
Motor skills
Ataxia: incoordination of movement - decomposition of movement - dysmetria, past-pointing - dysdiadochokinesia - rebound phenomenon of Holmes - gait ataxia, truncal ataxia, titubationIntention TremorHypotonia, Nystagmus
Archicerebellar Lesion: medulloblastomaPaleocerebellar Lesion: gait disturbanceNeocerebellar Lesion: hypotonia, ataxia, tremor
Syndromes
Cerebellar Ataxia
Ataxic gait and position: Left cerebellar tumor
a. Sways to the right in standing position
b. Steady on the right leg
c. Unsteady on the left leg
d. ataxic gait
Cerebellar Medulloblastoma
Cerebellar tumors on vermis
- Truncal Ataxia
- Frequent Falling
The child in this picture:
- would not try to stand unsupported
- would not let go of the bed rail if she was stood on the floor.
Are usually vascular, may be 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.
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 + intension tremors constitutes Charcot’triad, which is highly diagnostic of the disease.
Cerebellar lesions
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