The document summarizes the muscular system. There are three types of muscle tissue: cardiac, smooth, and skeletal muscle. Skeletal muscle is striated and voluntary, attaching to bones to enable movement. It contracts through the sliding filament model, where actin and myosin filaments interact powered by ATP. Motor neurons stimulate muscle fibers at the neuromuscular junction, and calcium ions link electrical signals to contraction. Muscle utilizes creatine phosphate, glycogen, and cellular respiration to fuel contractions and overcome fatigue. Muscular diseases can result from genetic mutations affecting muscle proteins.