Motor Systems Lecture Physio 67

Motor Systems Lecture Physio 67 - Motor Systems and Motor...

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Unformatted text preview: Motor Systems and Motor Contro Motor Control Motor Movements Reflex Responses Voluntary Movements Rhythmic Motor Patterns Muscle Control Must convey accurately timed commands not only to one muscle group but to many groups. Agonist and Antagonist muscle groups. Motor Plant Sensory Systems Sensory Systems Are vital to the correct functioning of motor systems Feedback Mechanism Slow Processing Mainly limited to slow movements & sequential acts. Feed Forward Mechanism Predicting movements Quick dynamic movements Hierarchy of Motor Control Hierarchy of Motor Control Spinal Cord Brainstem Cortical Motor Areas Muscle Receptors, Spinal Reflexes, and Local Control of Motor Local Control of Motor Movements Muscle Stretch Receptors: Muscle Spindles Golgi Tendon Organs Muscle Spindle Receptors: Specialized muscle fibers Nuclear chain fibers - short, slender, ~5 in number Nuclear bag fibers - thicker, longer, 2 types Dynamic (1) Static (1) Very sensitive to the rate of change of muscle length. Velocity Sensitivity Velocity Sensitivity Muscle Spindle Receptors: Motor neuron innervation is located on ends of intrafusal fibers. Regulate muscle length. Regulate muscle sensitivity Gamma Motor Neurons Gamma Motor Neurons Golgi Tendon Organ: Located at the junction of muscle and tendon. Looses myelination & braids itself within the collagen fibers of the tendon. Stretching of capsule compresses nerve endings, causing the neuron to fire. Very sensitive to changes in tension of muscle. The Stretch Reflex The Stretch Reflex Myotatic Reflex Myotatic Reflex Flexion - Withdrawal Reflex Spinal and Postural Spinal and Postural Mechanisms Mechanisms Mechanisms Mechanisms Neural circuits (microcircuits) within the spinal cord play an essential role in motor coordination. Interneurons are a vital player in these microcircuits Interneurons are a vital player in these microcircuits. Interneurons can be either inhibitory or stimulatory within the circuits they are residing. Divergence - the distribution of the output of a single neuron (or a group of neurons) to a number of target neurons by branching of the axon. Convergence - the processing of input from several neurons (or groups of neurons) onto one neuron (or neuronal group). Gating Gating- intermediate neurons (interneurons) or intermediate connections utilized by higher centers to preselect which of several possible responses will follow a stimulus. Spatial Organization Spatial Organization Temporal Organization Temporal Organization Renshaw Cell (neuron) - Inhibitory interneuron The connections of Renshaw cells to presynaptic motor neurons form a negative feedback system, which regulates the firing rate of the motor neurons....
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Motor Systems Lecture Physio 67 - Motor Systems and Motor...

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