Cerebellum & Basal Ganglia Prof.Mahmoud Samir Mohamed Quiz

Cerebellum

• The cerebellum is one of three brain areas contributing to coordination of movement, along with the motor cortex and basal ganglia.
• Despite its importance in movement coordination, the cerebellum does not play a primary role in sensory or motor function.
• If the cerebellum is destroyed, it does not lead to loss of sensation or paralysis, but causes devastating changes in movement performance.
• The cerebellum acts as a regulator of motor output, comparing intention with performance to compensate for errors.

Anatomy of the Cerebellum

• The cerebellum has three main divisions: Flocculonodular Lobe, Vermis and Intermediate Hemispheres, and Lateral Hemispheres.
• The Flocculonodular Lobe (vestibulocerebellum) receives inputs from visual and vestibular systems and controls axial muscles for equilibrium.
• Dysfunction in this system leads to ataxic gait, wide-based stance, and nystagmus.
• The Vermis and Intermediate Hemispheres (spinocerebellum) receive proprioceptive, cutaneous, visual, vestibular, and auditory inputs.
• The spinocerebellum controls the execution of movement, corrects for deviations, and modulates muscle tone.
• Lesions in the spinocerebellum lead to hypotonia (low muscle tone).
• The Lateral Hemispheres (cerebrocerebellar) receive inputs from the cerebral cortex and are involved in planning and preparation of movement, and evaluation of sensory information for action.

Basal Ganglia

• The basal ganglia complex consists of five nuclei: Putamen, Caudate Nucleus, Globus Pallidus, Subthalamic Nucleus, and Substantia Nigra.
• The basal ganglia contribute to both preparation and execution of movement, selectively activating some movements while suppressing others.
• Diseases affecting the basal ganglia can produce poverty and slowness of movement, disorders of muscle tone and postural reflexes, such as Parkinson's disease.
• Parkinson's disease symptoms include resting tremor, increased muscle tone or rigidity, slowness in movement initiation (akinesia), and execution (bradykinesia).
• Other diseases of the basal ganglia produce involuntary movements (dyskinesia), such as Chorea, Athetoses, and Dystonia.

Functional Differences between Basal Ganglia and Cerebellum

• The basal ganglia are concerned with internally generated movements, whereas the cerebellum is involved in visually triggered and guided movements.
• The cerebellum is more focused on the execution of movement, while the basal ganglia are more involved in the preparation and planning of movement.