Anatomy and Cell Biology 3319 Lecture Notes - Lecture 10: Alpha Motor Neuron, Muscle Spindle, Stretch Reflex
3 Jan 2018
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1a afferent neurons give dynamic information from the stretch of the muscles. Reflexes that are constantly working: the cerebral cortex has to override it: suppression of the constant on reflexes. Alpha lower motor neuron out of spinal cord to the extraskeletal muscle: for contraction. We need a means to override stretcher reflexes since they are always active. Summary: the motor unit comprises a group of extrafusal muscle fibers and the alpha motor neuron that innervates them. 1a sensory nerve has an excitatory synapse with the alpha motor neuron of the homonymous (synergist) alpha motor neuron to cause muscle contraction. Major descending pathways are the: corticospinal, corticobulbar, reticulospinal, vestibulospinal (postural) Going down the spinal cord: anterior corticospinal tract if do not decussate, lateral corticespinal tract if decussate. Info from cortex down spinal cord to send out info to the motor neurons. Control the precision and speed of skilled movements.
