Final answer:
The myocardium is involuntary muscle tissue found in the heart that contracts to pump blood throughout the body.
Step-by-step explanation:
The myocardium, or heart muscle, is involuntary muscle tissue.
Unlike voluntary muscles, such as skeletal muscles that can be consciously controlled, the myocardium is controlled by the autonomic nervous system and contracts involuntarily to pump blood throughout the body.
Additionally, the myocardium is striated, similar in structure to skeletal muscle, but differs in its irregular branching and the presence of intercalated discs.