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.
The microfilaments are arranged so that the fibers appear to have stripes (striations) in them. These are also called voluntary muscles.. Smooth muscle is involuntary, and is not under conscious control; the muscles in your digestive system are smooth muscles.The cells are individual and are found in sheets instead of long fibers. (Cardiac muscle has characteristics of both, but are not referred to in the question).here skeletal muscle is voluntary, cardiac muscle is autorhythmic (beats involuntarily; generates its own action potentials). 3. Smooth muscle: refers to the muscles that are controlled involuntarily by the brain, like those attached to the base of hair follicles or in the walls of the gastro-intestinal tract.
A muscle may act ordinarily either under the control of the will or without conscious control. Muscles that can be controlled at will are referred to as voluntary muscles. Those that are not under the control of the will (volition) are called involuntary muscles. Examples of involuntary muscles are the smooth muscles, which are muscles lacking striations when viewed under a microscope. This is why involuntary muscles are sometimes called non-striated or un-striped muscles.