What type(s) of muscle are striated and which structure(s) are responsible for that appearance?

Skeletal muscles are striated. Skeletal tissue has parallel arrays of long, cylindrical muscle fibers. The interior of each fiber is taken up by many long threadlike structures (myofibrils) that consist of row after row of contractile units. Because these rows are aligned the same way in the many myofibrils, skeletal muscle has a striated, or striped, appearance under the microscope.