The Human Brain : From Neurone to Nervous System

BASAL GANGLIA : STRUCTURE and SYNDROMES


  1. The Basal Ganglia consist of some large structures in the centre of the cerebral hemispheres; the Corpus Striatum, Globus Pallidus and Caudate Nucleus, which are linked functionally with the Substantia Nigra of the midbrain and the Subthalamic Nucleus

  2. These are connected together and have important projections via the thalamus, to the pre-motor and supplementary motor areas of the cerebral cortex (Brodmann's area 6).

  3. Spontaneous movements of the musculature occur commonly following lesions of the basal ganglia. The tremor of Parkinson's Disease, Choreiform movements of Huntington's disease, the slow writhing movements of Athetosis and the uncontrollable flinging movements of Hemiballismus can all be traced back to disorders in the basal ganglia.

  4. The tremor of Parkinson's Disease is characterized by involuntary, rhythmic and alternating movements of one or more body parts. Typically, Parkinsonian tremor occurs at rest and is suppressed during voluntary movement, and is rhythmical, with a frequency of 4–10 Hz.

  5. Other spontaneous movements are not rhythmic, and may not be suppressed by voluntary movement.
    • Chorea is a spontaneous uncontrollable rapid jerky movement, usually of distal muscles and/or the face.

    • Athetosis (slow chorea) is a slow, writhing movement predominantly in distal muscles.

    • Hemiballismus is a unilateral rapid, nonrhythmic, uncontrollable, wildly flinging movement affecting proximal muscles in the arm and/or leg.

The Basal Ganglia: Corpus Striatum, Globus Pallidus, Substantia Nigra, Subthalamic Nucleus


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