Muscle atrophy is the wasting or loss of muscle tissue, leading to decreased muscle mass and strength. It can result from disuse, malnutrition, aging, nerve damage, or various underlying medical conditions such as muscular dystrophies, spinal muscular atrophy, or chronic diseases. Symptoms include muscle weakness, reduced mobility, and fatigue. Diagnosis involves physical examination, neurological assessment, and sometimes imaging or electromyography. Treatment focuses on addressing the underlying cause, physical therapy, and nutritional support to preserve muscle function.