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The cerebellum:.

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Presentation on theme: "The cerebellum:."— Presentation transcript:

1 The cerebellum:

2 Cerebellum: Principally a motor organ Responsible for:
Regulation and control of muscle tone Coordination of movement, especially skilled, voluntary movement Control of posture and gait

3 Motoric movements: Willed: Cortical. Pyramidal motor system
Automatic: Static, postural. An expression of the extrapyramidal motor system Coordination of willed movements

4 Extrapyramidal system:
Cerebellum Basal ganglia

5 Cerebellum: None of the motor activities of the cerebellum reach conscious kinesthetic perception: It`s main role is to assist in the initiation and modulation of willed movements that are generated in the cerebral hemispheres

6 3 Parts: Flocculonodular lobe. Oldest portion. Archicerebellum.
Afferent fibers = proprioceptive impulses from vestibular nuclei. Equilibrium. Vestibulocerebellum

7 Anterior lobe: Paleocerebellum Spinocerebellum
Proprioceptive fibers from muscles and tendons. Dorsal spinocerebellar tract (lower limbs) and ventral spinocerebellar tract (upper limbs). Maintains posture and muscle tone.

8 Posterior lobe: Neocerebellum
Afferent fibers from cerebral cortex via the pontine nuclei and brachium pontis. Pontocerebellum Coordination of skilled movements that are initiated at a cerebral cortical level

9 Clinical signs in cerebellar disease:
Hypotonia Ataxia, Nystagmus Incoordination Disorders of equilibrium and gait

10 Basal ganglia:

11 Anatomic considerations:
No precise definition Caudate nucleus + Lentiform nucleus with it`s 2 subdivisions: Putamen Globus Pallidum

12 Physiology: “Brake and switch” theory
The basal ganglia function as a brake or switch The tonic inhibitory (brake) action of the basal ganglia prevent their target structures from generating unwanted motor activity Switch function: Refers to the capacity of the basal ganglia to select which motor program will be active at any given time

13 Other theories: “Motor programming”:
Role of the basal ganglia in the initiation, sequencing and modulation of motor activity.

14 Several motor syndromes:
Loss of voluntary movement with spasticity: Corticospinal tract involvement Incoordination: Cerebellum Involuntary movements—dystonia: Basal ganglia

15 Symptoms of basal ganglia disease:
Motor disorders: Deficits = negative symptoms or, Involuntary movements = positive symptoms (effects)

16 Negative: Bradykinesia, akinesia, loss of postural reflexes.
Positive: Tremor, rigidity, involuntary movements—dystonia, chorea etc..


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