PNB 2264 Lecture Notes - Lecture 14: Supplementary Motor Area, Primary Motor Cortex, Basal Ganglia
17 Dec 2018
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Stereotypic, do over again and again movements. Lower motor neurons originate in the ventral horn of the spinal cord. Axons leave via the ventral root out to the skeletal muscle. Organized somatotopically - corresponds to their anatomical relationship with the skeletal muscles. Proprioception - shows where your body is in space. Innervation of skeletal muscle (extrafusal + intrafusal) Muscle spindles = intrafusal muscle = sensory receptors. Innervated by afferent nerve fibers (that wind around the muscle fibers. Innervated by efferent motor neurons gamma motor neurons (that innervate at the striated ends. Transduce static length and rate of change of length of stretch muscles. Without gamma motor neurons, if you shorten the muscle for too long, it stops reporting. Gamma motor neurons allow you to be responsive at all muscle lengths. Quick clinical screen for the entire motor system. Located in the tendons to monitor tension. Responds more to tension due to contracting muscle.
