muscle fiber - /mus·cle/ (mus´'l) /fi·ber/ (fi´ber)
muscle fiber: any of the cells of skeletal or cardiac muscle tissue. Skeletal muscle fibers are cylindrical multinucleate cells containing contracting myofibrils, across which run transverse striations. Cardiac muscle fibers have one or sometimes two nuclei, contain myofibrils, and are separated from one another by an intercalated disk; although striated, cardiac muscle fibers branch to form an interlacing network.
Posted by - Anatomy in Motion (see photo)