What type of involuntary muscle tissue is found only in the heart?

Cardiac muscle is a specialized type of involuntary muscle tissue that is found exclusively in the heart. This muscle tissue is unique in its structure, with intercalated discs that allow for synchronized contractions necessary for effective pumping of blood. Unlike skeletal muscle, which is under voluntary control and can be found throughout the body, and smooth muscle, which is also involuntary but found in the walls of hollow organs, cardiac muscle has specific properties that enable it to function properly in the heart's rhythm and pump action.

Additionally, while striated muscle refers to the appearance of certain muscle types under a microscope, cardiac muscle is categorized separately from smooth muscle and has its own distinctive characteristics related to function and location. Therefore, the correct choice of cardiac muscle accurately identifies the specific type of involuntary muscle tissue that is unique to the heart, emphasizing its role in maintaining the essential function of circulation.