- Involuntary contraction of the muscle fibers innervated by a motor unit. Fasciculations can often by visualized and take the form of a muscle twitch or dimpling under the skin, but usually do not generate sufficient force to move a limb. They may represent a benign condition or occur as a manifestation of motor neuron disease or peripheral nervous system diseases. (Adams et al., Principles of Neurology, 6th ed, p1294)
Definition from: MeSH via Unified Medical Language System at the National Library of Medicine
- Muscular twitching involving the simultaneous contraction of contiguous groups of muscle fibers.
Definition from: Merriam-Webster's Medical Dictionary by Merriam-Webster Inc.
See also Understanding Medical Terminology.