Kinesiology 1080A/B Lecture Notes - Lecture 5: Extrafusal Muscle Fiber, Alpha Motor Neuron, Gamma Motor Neuron

• School: Western University
• Department: Kinesiology
• Course: Kinesiology 1080A/B
• Professor: Matthew Heath

Document Summary

The distribution of nerves to a part of the body. The number of muscle fibers innervation by a single alpha (a) motor neurons; can vary from a few to over a thousand. Precision of movement involved: extrafusal fibers. Power producing muscle fibers external with respect to muscle spindles (alpha. Muscle fibers inside of the muscle spindles innervated by a special system of fusimotor neurons (y-motorneurons) gamma motor neurons. Provide info to cns about position of muscle. Heavily myelinated transmit action potential quickly (impulse to extrafusal muscle fiber) Alpha motor unit and all the muscles it innervates. A unit of force production in skeletal muscles. Number of muscle fibers associated with a motor unit ranges from 10 (eye) to thousands (back muscle) Small neurons innervating intrafusal muscle fibers and changing sensitivity of muscle response to dynamic stretch. Intrafusal muscle fibers oriented in parallel with extrafusal muscle fibers. Polar connections between intrafusal and extrafusal fibers. Innervate fast and/or slow twitch muscle fibers.