what is responsible for the contraction of muscle fibers
The myofibrils are composed of actin and myosin filaments, repeated in units called sarcomeres, the basic functional units of the muscle fiber. The sarcomere is responsible for the striated appearance of skeletal muscle, and forms the basic machinery necessary for muscle contraction.The term muscle refers to multiple bundles of muscle fibers called fascicles. All muscles also contain connective tissue arranged in layers of fasciae.keletal muscle is made up of individual muscle cells or myocytes, known as muscle fibers. They are formed from the fusion of developmental myoblasts (a type of embryonic progenitor cell that gives rise to a muscle cell) in a process known as myogenesis. Muscle fibres are cylindrical, and multinucleated.