skeletal muscle

The structure of striated, or skeletal, muscle. Striated muscle tissue, such as the tissue of the human biceps muscle, consists of long fine fibres, each of which is in effect a bundle of finer myofibrils. Within each myofibril are filaments of the proteins myosin and actin; these filaments slide past one another as the muscle contracts and expands. On each myofibril, regularly occurring dark bands, called Z lines, can be seen where actin and myosin filaments overlap. The region between two Z lines is called a sarcomere; sarcomeres can be considered the primary structural and functional unit of muscle tissue.

skeletal muscle, in vertebrates, most common of the three types of muscle in the body. Skeletal muscles are attached to bones by tendons, and they produce all the movements of body parts in relation to each other. Unlike smooth muscle and cardiac muscle, skeletal muscle is under voluntary control. Similar to cardiac muscle, however, skeletal muscle is striated; its long, thin, multinucleated fibres are crossed with a regular pattern of fine red and white lines, giving the muscle a distinctive appearance. Skeletal muscle fibres are bound together by connective tissue and communicate with nerves and blood vessels. For more information on the structure and function of skeletal muscle, see muscle and muscle system, human.