KINE 3P94 Lecture Notes - Lecture 5: Gamma Motor Neuron, Intrafusal Muscle Fiber, Extrafusal Muscle Fiber
29 Feb 2016
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Pekn 3p94 lecture 5: monday, october 7, 13. The nervous system tells our muscles to contract. Reflexes bypass the brain, just go in and out thru spinal cord. Stimulus- hammer hitting knee: stretch of the quadriceps muscle and muscle spindles, causing inc in ia (and ii) afferent neuron firing. Mostly ia"s they tell you info about length of musc and change in musc length (velocity: increase in epsp onto (or excitation of) quadriceps a-mn, contraction of quad muscle. Greater ia/ii inhibitory interneuron activity inhibits hamstrings a-mn"s. Gamma motor neurons (fusimotor neurons: these are motor neurons- therefore sending. Ap"s from spinal cord out to muscle: so we have a-mn"s and gamma- mn"s that send info out to muscle, however, gamma-mn"s innervate intrafusal fibers and a-mn"s innervate extrafusal fibers, nuclear bag- ia a-mn"s, chain fibers- ii a-mn"s. Signals sent to a-mn"s and g-mn"s simultaneously: alters spindle sensitivity, better at detecting proprioceptive info.
