What type of muscle is responsible for involuntary movements in the body?

Smooth muscle is responsible for involuntary movements in the body. This type of muscle tissue is found in various internal organs, including the digestive tract, blood vessels, and the bladder. Unlike skeletal muscle, which is under conscious control and allows for voluntary movements, smooth muscle operates automatically without any need for conscious thought. For instance, smooth muscle contractions help move food through the digestive system and regulate blood flow by constricting or dilating blood vessels.

Cardiac muscle, while also involuntary, is specifically found in the heart and is specialized for rhythmic contractions to pump blood throughout the body. Striated muscle refers broadly to skeletal muscle and cardiac muscle, characterized by a banded appearance, but it does not describe muscle functioning involuntarily. Skeletal muscle is under voluntary control, enabling actions like walking or lifting objects. Therefore, smooth muscle is the most fitting answer when considering muscle types that facilitate involuntary movements.