part of a muscle attached by a tendon to a bone a muscle is composed of muscle fasciculi each surroundad by perimysium the fasciculi are composed of bundles of individual muscle fibers muscle cells each surrounded by endomysium the entire muscle is surrounded by a connective tissue sheath called epimysium or fascia b.enlargement of one muscle fiber the muscle fiber contains several myofibrils c.a myofibril extended out the end of the muscle fiber the banding patterns of the sarcomeres are shown in the myofibril d.a single sarcomere of a myofibril is composed mainly of actin myofilaments and myosin myofilaments the z disks anchor the actin myofilaments and the myosin myofilaments are held in place by the m line e.part of an actin myofilament is gnlarged f.part of a myosin myofilament is enlarged