FIBRILLATION By N., Pam M.S. - May 11, 2013 small and involuntary contraction of muscles from a spontaneous activation of muscle fibres or single muscle cells. It is especially applied to the heart. See arrhythmia. FIBRILLATION: "Joe suffered from fibrillation of his heart muscle." Related Psychology Terms EXTRAFUSAL FIBER GASTROINTESTINAL MOTILITY FAST MUSCLE FIBER CARDIAC MUSCLE CARDIOMYOPATHY MUSCLE TWITCH DYSTONIA MUSCLE RELAXANTS MUSCLE CONTRACTION SPASM Cite this page: N., Pam M.S., "FIBRILLATION," in PsychologyDictionary.org, May 11, 2013, https://psychologydictionary.org/fibrillation/ (accessed August 8, 2020).