Schematic model outlining the different phases of muscle regeneration. Muscle regeneration occurs in five interrelated and time-dependent phases (text in blue). The necrosis of muscle fibers activates a transient muscle inflammation, which is necessary for the removal of necrotic cellular debris. Inflammation is followed by a regeneration phase that is characterized by the activation of stem cell populations (satellite cells and other nonmuscle stem cells), which replace damaged myofibers. The fourth phase involves the remodeling of extracellular matrix and angiogenesis. The muscle regeneration is completed by the reinnervation of regenerating fibers.