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.
Noun. 1. involuntary muscle-a muscle that contracts without conscious control and found in walls of internal organs such as stomach and intestine and bladder and blood vessels (excluding the heart). smooth muscle.oun. 1. involuntary muscle-a muscle that contracts without conscious control and found in walls of internal organs such as stomach and intestine and bladder and blood vessels (excluding the heart). smooth muscle.