PSYC 427 Lecture Notes - Lecture 5: Alpha Motor Neuron, Neuromuscular Junction, Myocyte
Document Summary
Movement produced by large diameter mns that lie in the ventral horn of the spinal cord. Mn axon exits the spinal cord by the ventral root, traverses peripheral nerves until it reaches the target muscle (then divides) Branches widely to terminate on 100 to 1000 individual muscle fibres whose contraction it controls. The ensemble of mn and the muscle fibres that it innervates is called a motor unit. (this is the functional unit of muscle control. Motor unit = alpha motor neuron + set of muscle fibers that are innervated by the mn axon) Muscle fibres within a motor unit are spatially distributed within the target muscle (not all next to each other, they are spread out) Other mns innervating the same skeletal muscle clustered within the same motor nucleus in the ventral spinal cord. Functional connection between motor axon and the muscle fibre is a chemical synapse called a motor endplate.
