And notice we only have a single nucleus in any given smooth muscle cell. And that means smooth muscle cells are unique nucleated, just like cardiac muscle cells. Now, we also notice this network of three different types of filaments. So we have the thin filament and the thick filament that are also found in the cardiac and skeletal muscle. And we have a new type of filament known as the intermediate filament that is not found in skeletal and cardiac muscle. Now, thin filament is composed of actin, the protein actin, while thick filament is composed of the protein myosin.