Which term refers to visible and spontaneous contractions of muscle fibers?

• A. Atrophy
• B. Fibrillation
• C. Fasciculation
• D. Myopathy

Answer: (C)

The term that refers to visible and spontaneous contractions of muscle fibers is fasciculation. Fasciculations are small, involuntary muscle twitches that can be seen under the skin. These twitches are indicative of disturbances in the neuromuscular system and can occur when there is irritation or damage to the motor neurons or the peripheral nerves.

The presence of fasciculations can often be associated with various neurological conditions, but they can also occur in healthy muscles without any underlying pathological conditions. This visibility and spontaneous nature of fasciculations distinguish them from other muscular phenomena.

Atrophy refers to the wasting away or decrease in muscle mass, which is not related to visible contractions of muscle fibers. Fibrillation, on the other hand, involves rapid and uncoordinated contractions of muscle fibers but is typically not visible, as it occurs at a microscopic level. Myopathy refers to diseases that affect muscle tissue itself, which can lead to muscle weakness and dysfunction without necessarily causing visible contractions. Thus, fasciculation is the correct choice as it specifically denotes the spontaneous contractions that can be observed.