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

Cardiac muscle is specifically designed for the involuntary movements of the heart. This type of muscle tissue is unique to the heart and has the ability to contract rhythmically and continuously without conscious control. Cardiac muscle fibers are striated like skeletal muscle, but they are connected by intercalated discs, which facilitate the rapid transmission of electrical signals between cells. This structural feature allows for synchronized contractions, enabling the heart to pump blood effectively throughout the body.

The other types of muscle—skeletal, smooth, and ciliary—serve different functions and are under different types of control. Skeletal muscle is responsible for voluntary movements, smooth muscle controls involuntary movements in various systems like the digestive tract, and ciliary muscle is involved in controlling the lens shape in the eye, affecting focus. Thus, the distinctive characteristics of cardiac muscle make it the sole type responsible for the involuntary contractions necessary for heart function.