Which type of muscle makes up the heart?

• A. Skeletal muscle
• B. Smooth muscle
• C. Voluntary muscle
• D. Cardiac muscle

Answer: (D)

Cardiac muscle is the muscle of the heart. It’s a specialized involuntary tissue that forms the myocardium and drives the heart’s continuous, rhythmic contractions. Cardiac muscle looks striated like skeletal muscle but works automatically, without conscious control, thanks to its own conduction system and intercalated discs that coordinate a single, synchronized heartbeat. In contrast, skeletal muscle is voluntary and attached to bones for movement, while smooth muscle is non-striated and lines the walls of hollow organs and vessels. Because the heart must continually pump, cardiac muscle is perfectly suited for this role.