Muscle diseases are conditions that affect the muscles' ability to function properly. These diseases can lead to weakness, pain, and loss of muscle mass. Common types include muscular dystrophy, which is a genetic disorder causing progressive muscle degeneration, and myositis, an inflammation of the muscles often due to autoimmune issues. Symptoms of muscle diseases can vary widely but often include difficulty in movement, fatigue, and cramps. Diagnosis typically involves physical exams, blood tests, and imaging studies. Treatment options may include physical therapy, medications, and in some cases, surgery to improve muscle function and quality of life.