Anatomy and Cell Biology 3319 Lecture Notes - Lecture 9: Upper Motor Neuron, Alpha Motor Neuron, Anterior Grey Column

• School: Western University
• Department: Anatomy and Cell Biology
• Course: Anatomy and Cell Biology 3319
• Professor: Peter Merrifield

Document Summary

You cant make motor movements successfully without sensory input (ie proprioception is biggest influence on motor movement) The motor unit comprises a group of extrafusal muscle fibers and the alpha motor neuron that innervates them. The alpha motor neurons in the ventral horn of the spinal cord terminate on the extrafusal muscle fibres for muscle contraction. Review: we have a primary afferent that synapses on second order neuron; the second order neuron crosses over the midline, it either crosses over at the spinal chord level or medulla depending on which pathway we are talking about. Then it terminates on thalamus and third neuron that goes from thalamus to somatosensory cortex. So the difference is all about 2nd neuron. For motor neurnons (2 neuron cicuits), we have upper motor neurons; comes down and synapses on a lower 2nd motor neuron (in the ventral horn of the spinal chord).