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.
The structure of an involuntary muscle cell consists of a long, spindle-shaped cell without striations. The cells may occur as individual cells, in groups or as sheets. Contractions occur either in slow, spontaneous rhythms or as sustained contractions for longer durations. The involuntary muscle is one of three types of muscles found. The other two types are skeletal and cardiac. Skeletal muscle is a type of voluntary muscle, meaning it is controlled by the organism's will. The skeletal muscle is also referred to as a striated muscle because of the alternating muscle fibers that are light and dark colored.