What are the mechanisms by which thermal agents reduce muscle spasm?
Cold has its effect directly on the muscle, the intrafusal fibers of the muscle spindle mechanism, and sensory wrappings of the muscle spindles. Heat affects muscle spasm indirectly by slowing the firing rate of secondary afferents, increasing the firing rate of Golgi tendon organs, and decreasing the firing rate of efferent fibers to the muscle spindle (gamma fibers).