Why do muscles appear to be striped?

Muscles appear striped due to the arrangement of myofibrils within muscle fibers, which contain repeating units called sarcomeres. These sarcomeres are made up of overlapping thick (myosin) and thin (actin) filaments, creating a pattern of light and dark bands when viewed under a microscope. The alternating bands of light and dark give skeletal and cardiac muscles their characteristic striated appearance. This striation is crucial for the contraction mechanism of these muscles.