BIOL 031 Lecture Notes - Lecture 25: Golgi Tendon Organ, Gamma Motor Neuron, Alpha Motor Neuron

• School: College of The Sequoias
• Department: Biology (BIOL)
• Course: BIOL 031
• Professor: Trimble

Document Summary

External stretch- external force (weight) on muscle or contraction of antagonistic muscle (e. g. quadriceps-hamstrings) Internal stretch- activated gamma motor neurons cause contraction of intrafusal fiber, stretching midsection of spindle. Afferent (sensory) fiber synapse directly on alpha motor neuron, causing contraction of extrafusal muscle fibers of the stretched muscle. Reciprocal inhibition- afferent (sensory fiber synapse on interneurons, which then. Inhibit motor neurons to the antagonistic muscle (e. g. quadriceps-hamstrings) Relay of information to brain (cerebellum) also occurs via dorsal white columns of the spinal cord. The length of the muscle spindle organ, and therefore its sensitivity to stretch, is regulated by activation/ inhibition of the gamma motor neuron reflex arc. The deep tendon reflexes counterbalence the stretch reflexes to allow smooth motion to occur, especially during complex activity (e. g. running, swimming, etc. ) The flexor (withdrawl) reflex- allows the withdrawl of limb from a painful stimulus.