What type of muscle is involuntary and found in the walls of the heart?

Cardiac muscle is a specific type of striated muscle that is involuntary and exclusively located in the walls of the heart. Its involuntary nature means that it operates without conscious control, coordinating heartbeats to pump blood throughout the body. This muscle type is unique in its ability to contract rhythmically and continuously, which is essential for maintaining a consistent heartbeat.

Cardiac muscle cells are interconnected by intercalated discs, which facilitate rapid electrical signaling, allowing for synchronized contractions. While skeletal muscle is also striated, it is voluntary and primarily responsible for movement of bones. Smooth muscle, found in various organs including the digestive tract and blood vessels, is also involuntary but does not display the striations characteristic of cardiac and skeletal muscle.

Thus, the choice of cardiac muscle accurately reflects the characteristics of the muscle type that is both involuntary and located in the heart.