Cerebellum ppt

DR NILESH KATE
MBBS,MD
ASSOCIATE PROF
ESIC MEDICAL COLLEGE, GULBARGA.
DEPT. OF PHYSIOLOGY
CEREBELLUM

OBJECTIVES
 Physiological Anatomy
 Neural circuits & neuronal activity
 Connections
 Functions
 Applied physiology.

Cerebellum.
 Largest part of hind brain.
 Called “silent area.”
 Weight- 150 gms.
Friday, January 16, 2015

Physiological anatomy.
 External features .
 Anatomical parts.
 Anatomical divisions.
 Phylogenetically divisions.
 Functional divisions.
 Histological structure.

External features
 Surfaces .
 Folia.- transverse
folds
 Fissures.
 Primary
 Horizontal
 Posterolateral.

Anatomical parts
 Parts of vermis.
 Lingula
 Central lobule
 Culmen
 Declive
 Folium
 Tuber
 Pyramis
 Uvula
 Nodule.
 Parts of hemisphere.
 No lateral projection.
 Alae
 Anterior quadrangular lobule
 Posterior quadrangular
lobule
 Superior semilunar lobule
 Inferior semilunar lobule.
 Biventral lobule
 Tonsil
 Flocculus.

Anatomical divisions
 Anterior lobe.
 Posterior lobe.
 Flocculonodular lobe..

Phylogenetically
divisions
 Archicerebellum
 Floculonodular lobe
 Lingula
 Paleocerebellum
 Anterior lobe except – lingula
 Posterior lobe – pyramis, uvula & paraflocculus.
 Neocerebellum.
 Whole posterior lobe except –pyramis & uvula.

Functional divisions.
 Vestibulocerebellum.
 Consists of
Floculonodular lobe
 Vestibular connections
 N. fastigeal – effector N.
 Control body posture &
equilibrium.
 Spinocerebellum.
 Consists of
Paleocerebellum.
 N Interpositus. – effector N.
 Postural reflexes.
 Corticocerebellum.
 Central cerebellum
 Dentate N.- effector
nucleus.
 Smooth performance.

Functional divisions.

Histological structure.
 Cerebellar cortex.
 Molecular layer.
 Purkinje cell layer.
 Granule cell layer.
 White matter.
 Projection fibres.
 Association fibres.
 Commissural fibres.
 Deep cerebellar nuclei.
 Dentate nucleus.
 Emboliform nucleus.
 Globossus nucleus.
 Fastigeal nucleus.

Histological structure.

Cerebellar cortex.
 Molecular layer.
 Stellate cells
 Basket cells.
 Purkinje cell layer.
 Granule cell layer.
 Granule cells
 Golgi cells.

Cerebellar cortex.

Sensory inputs.
 Climbing fibres
 Inferior olivary nucleus
 Cerebellum.
( purkinje cells)
 Mossy fibres.
 Spino, vestibulo,
reticulo, cuneo &
corticoponto
 Cerebellum
(Glomerulus)
Olivocerebellar tract.

Sensory inputs.

White matter.
 Projection fibres.  Association fibres.
 Commissural fibres.

Deep Cerebellar Nuclei.
 Dentate nucleus.
 Emboliform
nucleus.
 Globossus nucleus.
 Fastigeal nucleus.
Near roof of IV
ventricle.

Neural circuits & neuronal
activity.
 Afferents of cerebellar cortex.
 Climbing Fibres.
 Mossy Fibres.
 Neuronal activity of deep cerebellar circuits
 Feed forward inhibition of purkinje cells.
 Feed forward inhibition of Granule cells.
 Feed back inhibition of Granule cells.
 The reverberating circuits.
 Neuronal activity of deep cerebellar nuclei.

Afferents of cerebellar cortex.
 Climbing Fibres.  Mossy Fibres.

Neuronal activity of deep
cerebellar circuits
 Feed forward inhibition of Purkinje cells.
 Mossy fibres Granule cells
 Purkinje cells. Basket cells.
 Feed forward inhibition of Granule cells.
Mossy fibres Granule cells.
Golgi cells
 Feed back inhibition of Granule cells.

Neuronal activity of deep
cerebellar neuclei.
Cerebral cortex motor
pathway.
spinal cord.
Thalamus brainstem nuclei.
Deep cerebellar nuclei.
Climbing fibres, mossy fibres.

Connections of cerebellum.
 Cerebellar Peduncles..
 Inferior
 Afferents
 Dorsospinocerebellar.
 External arcuate
fibres.
 Vestibulocerebellar
tract.
 Oliocerebellar tract.
 Reticulocerebellar
tract.
 Middle.
 Afferents. – cerebro-
pontine – cerebellar.
 Superior
 Afferent –
 Tectocerebellar
 Ventral
spinocerebellar
 Efferent –
 Dentorubral
 Dentothalamic
 Mid-brain.

Afferent connections
 Dorsal spinocerebellar tract. (external)
 Ventral spinocerebellar tract. (Internal)
 Cuneocerebellar tract.
From accessory cuneate N.
 Olivocerebellar tract.
From brainstem, SC, cortex

 Cortico-ponto-cerebellar tract.
 Tectocerebellar tract.
From superior colliculi (visual impulses)&
inferior colliculi (auditory impulses)of
tectum of mid brain.
 Vestibulocerebellar tract. (position &
movement of head)
 Rubrocerebellar tract. ( from motor cortex )
 Reticulocerebellar tract.

Localization of sensory
impulses to cerebellum.

Efferents connections.
 Dento-rubro-thalamo-
cortical pathway.
 Cerebello-thalamic-
cortical pathway.
 Cerebelloreticular
pathway.
 Cerebellovestibular
fibres.
 Cerebello-olivary
fibres.
 Oculomotor nerve &
tectum.

Efferent connections.

Functions of cerebellum.
 Control of body posture & equilibrium.
 Control of muscle tone & stretch reflex.
 Control of voluntary movements.

Control of body posture &
equilibrium.

Control of muscle tone &
stretch reflex.

Control of voluntary movements.

Mechanism of action.
 Comparator function.
 Damping action.
 Timing & programming the movements.
 Control of ballistic movements.
 Servomechanism.

Comparator function.

Other functions of cerebellum.
 Autonomic system (through Hypothalamus &
reticular formation.)
 Ascending sensory pathway. (through
reticular formation & thalamus)
 Eyeball movements. ( through vestibular
nuclei)

Cerebellar lesions.
 Common causes.
 Signs of cerebellar dysfunction.
 Tests .

Common causes.
 Vascular occlusions (thrombosis)
 Tumor
 Injuries.

Signs of cerebellar dysfunction.
 Tone & posture disturbance
 Atonia or hypotonia
 Attitude changes.
 Rotation of face to opposite side
 Lowering of shoulder.
 Outward rotation & abduction of leg.
 Deviation movements.
 Effect on deep reflexes. (weak & pendular)

Signs of cerebellar dysfunction.
 Equilibrium disturbance. (drunken gait)
 Movements disturbance.
 Ataxia
 Intention tremors
 Nystagmus.
 Dysarthria.
 Astasia.

Clinical tests of cerebellar
dysfunction.
 Upper limb
 Finger nose test
 Diadokokinesia.
 Rebound phenomenon.
 Past pointing.
 Lower limb.
 Rombergs test.
 Tandem gait.

Tests .

Cerebellum ppt

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