UMass Amherst KIN 460 - 11- Proprioception (18 pages)

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11- Proprioception



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11- Proprioception

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Pages:
18
School:
University of Massachusetts Amherst
Course:
Kin 460 - Motor Control

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Kinesthetic Organs Proprioception The 6th sense 6 sense TheProprioception sense of position and movement of self 6th sense forgotten in th the count of the senses Information about position and movements of our limbs muscle spindle Golgi tendon organ joint receptors and relative to the environment vestibular system Proprioception can lead to Kinesthesis conscious sense of position and movement Overview What is the function of muscle spindles Golgi tendon organs joint receptors A simple reflex circuit the knee jerk response Function of gamma motor neurons Muscles extrafusal fibers muscle spindles Axon of alpha motor neuron extrafusal fibers Axons of Gamma motor neurons Ia and II afferents Ia primary endings II secondary endings Nuclear chain fiber Nuclear bag fiber Intrafusal fibers Spindle capsule Top Structure of a muscle spindle fibre Bottom Structure of a nuclear bag fibre and nuclear chain fibre II afferent fibers respond to change in muscle length static Ia afferent fibers respond to rate of change of length dynamic AND muscle length static Dynamic response is proportional to muscle lengthening velocity Overview What is the function of muscle spindles Golgi tendon organs joint receptors Golgi tendon organ GTO Tension through the muscle tendon junction will lead to membrane depolarization of receptor and AP in axon Afferent fibre type is Ib Golgi Tendon Organ Under what conditions does the Ib afferent fire Muscle stretch Muscle contraction alpha MN gamma MN Stretch will cause some firing Contraction generating force causes greater activation Greater force the greater the activation Negative feedback regulation of muscle tension by Golgi tendon organs GTO Maintains steady force level fatigue Inhibits large forces Schematic of the mechanisms of action of two kinds of proprioceptors in voluntary muscles muscle spindles that respond to muscle length X and rate of change of length Golgi tendon organs that signal muscle tension T or force Overview What is the function of muscle spindles Golgi tendon organs joint receptors Joint receptors Range of receptors associated with joint in capsule with ligament or tendon on fat pads Depending on location specialized receptors respond to stimuli reflecting changes in joint movement or loads Stretch responses from ligaments tendons Load pressure measures Extremes pain Mechanical stimulus leads to change in ion conductance Joint receptors Originally thought to only code limits of joint angle Evidence now that specific receptors are sensitive to specific ranges including mid range Individual receptors have responses to specific range of joint angles Therefore joint angle may be coded by combinations of receptors Joint receptors Evidence that muscle receptors work tendon vibration experiments



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