01:146:245 Lecture Notes - Lecture 16: Upper Motor Neuron, Motor Neuron, Brainstem

• School: Rutgers University
• Department: Cell Biology and Neuroscience
• Course: 01:146:245
• Professor: Professor Wilhelms

Document Summary

~upper motor neurons descend onto circuits of lmn and modulate activity. ~upper motor neuron cell bodies are in cortex or brainstem nuclei. ~so upper motor neurons do not directly synapse with lmn. ~the interneurons also get sensory input, important for reflexes. Any command for movement, whether voluntary or reflexive, goes through lmn. Their descending axons synapse with interneurons, and (rarely) directly with lmn. Cortical pathways important for planning, initiating, directing voluntary movement. Detects motor error when the executed movement is different from intended. Prime upper motor neuron circuits for initiation of movement. ~but each muscle is innervated by several neurons. ~all the neurons for a single muscle = its neuron pool. ~the motor neurons are clustered in the spinal cord and run parallel to spinal cord. ~there is relationship between the location of the motor neuron pools and location of their muscles. This relationship is lengthwise and mediolateral in spinal cord.