These are about 8 nm in diameter and, being the thinnest of the cytoskeletal filaments, are also called microfilaments. (In skeletal muscle fibers they are called thin filaments.) Some functions of actin filaments: 1  form a band just beneath the plasma membrane that.  provides mechanical strength to the cell.
Muscle tissue varies with function and location in the body. In mammals the three types are: skeletal or striated muscle; smooth or non-striated muscle; and cardiac muscle, which is sometimes known as semi-striated.n vertebrates, there is a third muscle tissue recognized: 1  Cardiac muscle (myocardium), found only in the heart, is a striated muscle similar in structure to skeletal muscle but not subject to voluntary control.
Both smooth muscle and cardiac muscle can be classified as involuntary muscles. Smooth muscle is comprised of spindle-shaped cells that have no striations and is found in numerous locations throughout the human body. Cardiac muscle is striated rather than smooth, and is found only within the walls of the heart.