BPK 306 Lecture Notes - Lecture 22: Gamma Motor Neuron, Alpha Motor Neuron, Rubrospinal Tract

• School: Simon Fraser University
• Department: Biomedical Physio & Kines
• Course: BPK 306
• Professor: Sam Doesburg

Document Summary

Motor neurons integrate inputs from different levels" of the nervous system. Includes descending control from cortical and subcortical structures (ex. corticospinal tract, rubrospinal tract, and indirect cortical and subcortical pathways: there is also segmental control from various afferents (ex. Motor neurons are recruited based on motor neuron size which is related to their input resistance ( size principle") Often alpha and gamma motor neurons are co-activated so that muscle spindles can provide motor feedback to the cns. Motor neuron output drives muscle contraction and force/velocity: define a motor unit and describe the order of recruitment of motor units during skeletal muscle contraction of varying strengths. 2: to increase force need -> faster firing or more nt release, muscle fibers of each motor unit are scattered over a large territory of a muscle. Small motor units are recruited first, then firing rate needs to be increased to then recruit larger units: when more motor units are recruited, the force produced increases.