Physiology of spinal cord Physiology of medulla midbrain

Physiology of spinal cord. Physiology of medulla, midbrain and diencephalon Author ass. prof. N. M. Volkova

Video

• 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.

• 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.

• 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.

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.