I think you meant the three types of muscles, because i couldnt find three functions anywhere. Types of muscles Different types of muscle respond, contract, and relax at different rates. Skeletal muscles are striated (have distinct bands) made up of fibres (long cells). The cells are multinucleated (many cell nuclei) and contract and relax quickly. These are voluntary muscles attached to the skeleton that help to move the bones. There are nearly 700 skeletal muscles spread all over the body. Visceral muscles are smooth and without banding. They have short fibres and single cell nuclei. These are involuntary muscles e.g. found in walls of blood vessels and viscera (organs in the abdominal cavity). Cardiac muscles are striated (but less distinct than skeletal muscles), and are involuntary

sorry as a massage therapist there is three type also known as m.p.h. no not miles per hour but 1.movement 2.posture 3.heat

The muscles plays four important roles in the body: it produces movements, maintains posture, stabilizes joints, and generates heat. PRODUCING MOVEMENT: just as movements of the human body is a result of muscle contraction.mobility of the body as a whole reflects the acitivity of skeletal muscles, which are responsible for all locomotion (walking,swimming, and cross-country skiing, for example) and manipulation. they enable us to respond quickly to changes in the external environment.these are distinct from the smooth muscle of blood vessel walls and cardiac muscle of the heart, which work together to circulate blood and maintain blood pressure, nad the smooth muscle of other hollow organs, which forces fluids (urine, bile) and other substances (food, a baby) through internal body channels. MAINTAING POSTURE: ew are rarely aware of the workings of the skeletal muscles that maintain body posture.yet, they function almost continuesly, making one tiny adjustment after another so that we can maintain an erect or seated posture despite the never-ending downward pull of gravity. STABILIZING JOINTS: as the skeletal muscles pull on the bones to cause movements, they also stabilize the joints of the skeleton.indeed, muscle tendons are extremely important in reinforcing and stabilizing joints that have porly fitting articulating surfaces (the shoulder joint, for example). GENERATING HEAT: the fourth function of muscle, generation of body heat, is a by-product of muscle activity.as ATP is used to power muscle contraction, nearly three quater of its energy escapes as heat.this heat is vital in maintaining normal body temperature.since skeletal muscle accounts for at least 40per cent of body mass, it is the muscle type most responisble for heat generation.

Yes.He is right.Those are the roles of muscles. the word "voluntary" is just a characteristics. You can't control smooth and cardiac muscle. You can't control your heart beat and whether your stomach should digest food.