Which type of muscle is striated and involuntary?

The correct answer, cardiac muscle, is characterized by its striated appearance and involuntary control. It is found exclusively in the heart and plays a crucial role in pumping blood throughout the body. The striations in cardiac muscle are due to the organized arrangement of actin and myosin filaments, similar to skeletal muscle, which allows for coordinated contractions. However, unlike skeletal muscle, which is under voluntary control, cardiac muscle functions automatically and is regulated by the autonomic nervous system, ensuring the heart beats rhythmically without conscious thought. This involuntary nature is essential for maintaining a stable heart rhythm and is why cardiac muscle is specifically categorized as striated and involuntary, distinguishing it from skeletal muscle, which is striated and voluntary, and smooth muscle, which is involuntary but non-striated. The term "voluntary muscle" is a broader classification that does not accurately capture the unique attributes of cardiac muscle.