Cardiac muscle cells are found in the heart’s walls, are striped (striated), and are controlled involuntarily. 

Smooth muscle fibers, with the exception of the heart, are situated in the walls of hollow visceral organs (such as the liver, pancreas, and intestines), seem spindle-shaped, and are similarly controlled involuntarily. 

Skeletal muscle fibers are found in muscles that connect to the bones. They have a striated look and are self-contained.