the muscular system is responsible for the movement of the human body. Attached to bones of the skeletal system are about 700 named muscles that make up roughly half of a person's bodyweight. Each of these muscles is a discrete organ constructed of skeletal muscle tissue, blood vessels, tendons, and nerves. Muscle tissue is also found inside of the heart digestive organ, and blood vessels. In these orga, muscles serve to move substance thoughout the body