Which type of muscle tissue is involuntary and found in the heart?

• A. Skeletal muscle
• B. Cardiac muscle
• C. Striated muscle
• D. Smooth muscle

Answer: (B)

Cardiac muscle is the type of muscle tissue that is involuntary and specifically found in the heart. This specialized muscle tissue is unique because it is striated, much like skeletal muscle, but unlike skeletal muscle, it operates without conscious control. Cardiac muscle fibers are branched and interconnected, allowing for coordinated contractions that are essential for pumping blood throughout the body. These contractions are regulated by the heart's pacemaker cells, which ensures a rhythmic heartbeat.

While skeletal muscle is also striated, it is under voluntary control, allowing movements to be consciously initiated. Smooth muscle, found in various organs and systems including blood vessels and the digestive tract, is also involuntary but does not have the striations seen in cardiac and skeletal muscles. Thus, cardiac muscle is uniquely characterized by its involuntary nature and its specific location in the heart, making it the correct answer.