Muscular contractions refer to the involuntary or voluntary tightening and relaxing of muscles. These contractions are the result of messages sent by the brain to the muscles and can occur for various reasons such as exercise, injury, or medical conditions. Synonyms for muscular contractions include muscle spasms, cramps, twitches, convulsions, and myoclonus. Muscle spasms are sudden and painful contractions that can occur in any muscle group. Cramps are prolonged and intense muscle contractions that can occur due to dehydration or overexertion. Twitches are involuntary, brief contractions that can occur in any muscle group and are usually harmless. Convulsions are severe and uncontrollable muscle contractions, and myoclonus is the sudden, involuntary jerking of a muscle or muscle group.