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

Cardiac muscle is the type of muscle that is involuntary and specifically found in the heart. This muscle type is unique because it has a specialized structure that allows for the rhythmic and continuous contractions required to pump blood throughout the body. It is characterized by a branched structure and contains intercalated discs, which facilitate communication and synchronized contraction between the muscle fibers. This involuntary nature means that cardiac muscle contractions are not consciously controlled, allowing the heart to function autonomously and efficiently.

In contrast to cardiac muscle, skeletal muscle is under voluntary control and is attached to the skeleton, allowing for movement of the body. Smooth muscle, while also involuntary, is found in the walls of hollow organs such as the intestines and blood vessels, not in the heart. Striated muscle refers to the appearance of skeletal and cardiac muscle under a microscope due to the organized arrangement of muscle fibers, but this term isn't specific enough to denote the unique involuntary characteristics of cardiac muscle. Therefore, the distinction of cardiac muscle being involuntary and located in the heart is essential in understanding its importance in the circulatory system.