Skeletal (or striated) muscle consists of muscle fibers, which are long, cylindrical multinucleated cells with diameters of 10-100 μm. During embryonic muscle development, mesenchymal myoblasts (L. myo, muscle) fuse, forming myotubes with many nuclei. Myotubes then further differentiate to form striated muscle fibers. Elongated nuclei are found peripherally just under the sarcolemma, a characteristic nuclear location unique to skeletal muscle fibers/cells. A small population of reserve progenitor cells called muscle satellite cells remains adjacent to most fibers of differentiated skeletal muscle. Source: Junquiera’s Basic Histology and Atlas, 14th Edition