PHSL-P 416 Lecture Notes - Lecture 18: Alpha Motor Neuron, Muscle Spindle, Proprioception
Document Summary
Henneman"s size principle, that motor units are recruited from small diameter to large diameter fibers. Frequency of firing is just how fast the muscle fires. This is our primary mechanism for increasing force production. Inhibition that prevents muscles from firing too rapidly, kind of like a refractory period. It takes ~8 seconds to clear any inhibitory effects between stimuli. Proprioceptors give the body a sense of where it is in space. Primary proprioceptors are the muscle spindles, which sense changes in muscle length and velocity. This is the amount of movement that occurs in maintaining upright posture. Nobody can stand completely still without any muscle activity. During standing, micro adjustments are being made between the muscles. Sway is the measurement of how far the center of pressure shifts. There are no interneurons between ia and alpha motor neurons. Innervation ratio is how many nerve fibers there are for a given muscle.
