actin filaments are essential for movements of cells in eucaryotes. such as cells crawling along a surface, the act of phagocytosis, and cell division
myofilament
Actin and myosin are proteins. Protein is a broad category of molecules.
The basic unit of muscular contraction; the sarcomere.
actin and myosin are myofillaments that make up myofibrils (part of a muscle fibre)(so therefore : muscle is an actin or myosin containing structure