Involuntary jerks, also known as spasms, are sudden, involuntary movements of the body caused by muscle contractions. These contractions can be caused by a variety of factors, including stress, fatigue, and certain medical conditions. Spasms can affect any part of the body, including the arms, legs, and face. They can range from mild to severe and can last for a few seconds or several minutes. Treatment for spasms depends on the underlying cause and may include physical therapy, medications, or lifestyle changes.