Fasciculations SNOMEDCT_US:82470000 Fasciculations are observed as small, local, involuntary muscle contractions (twitching) visible under the skin. Fasciculations result from increased irritability of an axon (which in turn is often a manifestation of disease of a motor neuron). This leads to sporadic discharges of all the muscle fibers controlled by the axon in isolation from other motor units. HP:0007092 Fasciculation Muscle fasciculation This finding can be visible clinically and can be demonstrated by electromyography (EMG). HP:0002380 HP:0002468 UMLS:C0015644 Involuntary movements muscle fasciculation fasciculations; muscle fasciculation