Physiology of spinal cord. Physiology of medulla, midbrain and diencephalon

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Physiology of spinal cord. Physiology of medulla,
midbrain and diencephalon

• Author
• ass.prof. N.M. Volkova

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• Passive stretch of the muscle activates the
  spindle stretch receptors and causes an increased
  rate of action potentials in the afferent nerve.
• Contraction of the extrafusal fibers removes
  tension on the stretch receptors and lowers the
  rate of action potential firing.

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• As the ends of the intrafusal fibers contract in
  response to gamma motor neuron activation, they
  pull on the center of the fiber and stretch the
  receptor.
• The black arrows indicate direction of
  action-potential propagation.

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• Postural changes with stepping. (Left) Normal
  standing posture. The line of the center of
  gravity falls directly between the two feet.
  (Right)
• As the left foot is raised, the whole body leans
  to the right so that the center of gravity shifts
  and is over the right foot.

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Diencephalon

• The diencephalon is the part of the forebrain
  that contains such important structures as the
  thalamus, hypothalamus, posterior portion of the
  pituitary gland, and pineal gland.
• The hypothalamus performs numerous vital
  functions, most of which relate directly or
  indirectly to the regulation of visceral
  activities by way of other brain regions and the
  autonomic nervous system.