Page 27 - UNIT 3

7.5. Syndromes due to lesions of the basal ganglia.

Parkinson’s disease & Huntington’s disease (Huntington’s Chorea).

8. INTEGRATION OF THE TOTAL MOTOR CONTROL.

8.1. The spinal cord level.

In the spinal cord are settled local patterns of movement for all muscle areas of the body, such as
withdrawal reflexes. It’s also the locus of complex patterns of rhythmical motions, such as to-and-fro
movement of the limbs for walking, plus reciprocal motions on opposite sides of the body or of the
hindlimbs versus the forelimbs.

All these patterns of the cord can be commanded into action by higher levels of motor control, or they
can be inhibited while the higher levels take over control.

8.2. The hindbrain level.

The hindbrain provides two major functions for general motor
control of the body:

1. Maintenance of axial tone of the body for the purpose of
standing
2. and continuous modification of the degrees of tone in the
different muscles in response to information from the
vestibular apparatuses for the purpose of maintaining
body equilibrium.

8.3. The motor cortex level.

The motor cortex is the main producer of the activating motor signals to the spinal cord. It sends
sequential and parallel commands that set into motion various cord patterns of motor action, changes
the intensities of the patterns, modify their timing, etc.

The corticospinal system replaces the cord patterns by orders from the brain stem or cerebral cortex.
The cortical patterns are complex and need to be "learned," whereas cord patterns are mainly
determined by heredity.

8.4. Cerebellum level.

The cerebellum is involved in muscle control at the level of:

1. The spinal cord especially to enhance the stretch reflex, through the long stretch reflex signal
transmitted to the cerebellum.
2. The brain stem level, to make the postural movements of the body, especially the rapid
movements required by the equilibrium system, without abnormal oscillations.
3. The cerebral cortex level, providing many accessory motor functions, as extra motor force for
turning on muscle contraction at the start of a movement and near the end, the cerebellum
turns on antagonist muscles with the right time and force. All this turn-on/turn-off patterning

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