What type of muscle makes up the walls of the heart?

The correct answer is cardiac muscle, which is specifically designed for the unique functions of the heart. Cardiac muscle is an involuntary striated muscle tissue that is found only in the heart. Unlike skeletal muscle, which is under voluntary control and responsible for the movement of limbs, cardiac muscle operates autonomously, ensuring that the heart continuously pumps blood throughout the body without conscious input.

Cardiac muscle fibers are interconnected, allowing them to work as a single unit, which is essential for the coordinated contraction of the heart. This structural characteristic ensures that when one section of the heart contracts, it can efficiently trigger the rest of the muscle to contract in a synchronized manner, optimizing blood flow.

In contrast, skeletal muscle primarily facilitates movement of the bones and is attached to the skeleton, while smooth muscle is found in the walls of hollow organs and is also involuntary but lacks the striations seen in cardiac muscle. Connective tissue includes various types, such as tendons and ligaments, but does not contract and therefore does not contribute to the heart's pumping action. Thus, understanding the specific roles and characteristics of these different muscle types highlights why cardiac muscle is the correct choice for the question.