For instance, most of us know about the biceps muscles in our arms. Skeletal muscle is the kind of muscle that we will see and really feel. When a body builder works out to increase muscle mass, skeletal muscle is what's being exercised. Skeletal muscles attach to the skeleton and are available in pairs -- one muscle to maneuver the bone in one route and one other to maneuver it back the other way. These muscles normally contract voluntarily, meaning that you consider contracting them and your nervous system tells them to take action. They can do a short, single contraction (twitch) or an extended, sustained contraction (tetanus). Smooth muscle is found in your digestive system, CircuPulse Blood vessels, bladder, airways and, in a feminine, the uterus. Smooth muscle has the power to stretch and maintain tension for lengthy durations of time. It contracts involuntarily, which means that you simply don't have to think about contracting it as a result of your nervous system controls it robotically.