There are numerous diseases associated with the muscular system. According to the U.S. National Library of Medicine and the National Institutes of Health, muscular system disorders can cause pain, weakness and even paralysis, and possible causes of muscular system disorders include overuse injuries such as strains, genetics, certain types of cancer, inflammatory conditions, nerve diseases, infections and certain medications. Diseases of the muscular system can range from mild to severe.
Myasthenia Gravis
Myasthenia gravis is a disease that affects the muscular system. According to the National Institute of Neurological Disorders and Stroke, a division of the National Institutes of Health, myasthenia gravis is "a chronic autoimmune neuromuscular disease characterized by varying degrees of weakness of the skeletal muscles of the body." The institute adds that myasthenia gravis involves muscle weakness made worse with exertion or activity, and that prolonged periods of rest are helpful in reducing myasthenia gravis-related muscle weakness. Muscles that are commonly affected by myasthenia gravis include the muscles that control eye and eyelid movement, muscles of facial expression and the muscles that control chewing, talking, swallowing, breathing and neck and extremity movements. The institute states that myasthenia gravis is caused by the impaired transmission of nerve signals to the muscles.
Rhabdomyosarcoma
Rhabdomyosarcoma is a type of cancer associated with the muscular system. The American Cancer Society says that rhabdomyosarcomas are malignant tumors found in skeletal muscle and that children have a higher risk of rhabdomyosarcomas than adults. Rhabdomyosarcomas often grow in a person's arms or legs, although they can also originate in the head and neck area, or in a person's reproductive and urinary organs. According to the cancer society, there are two principle types of rhabdomyosarcoma--embryonal and alveolar. Embryonal rhabdomyosarcoma, the most common type of rhabdomyosarcoma, typically affects infants and children and occurs in the head and neck region, bladder, vagina, prostate and testicles. Alveolar rhabdomyosarcoma is less common and typically affects older children and adolescents. It occurs most frequently in the trunk, arm and leg muscles.
Becker Muscular Dystrophy
Becker muscular dystrophy is a disease that affects the muscular system. According to the Muscular Dystrophy Association, Becker muscular dystrophy, or BMD, is one of nine types of muscular dystrophy. Muscular dystrophies are genetic, progressive and degenerative diseases that target a person's skeletal or voluntary muscles. The cause of BMD is inadequate generation of dystrophin--a protein that binds the muscle cells and keeps them intact--and that BMD's onset typically occurs during adolescence or adulthood. Common symptoms associated with BMD include muscle weakness and wasting throughout the body, especially in the hips, pelvis, thighs and shoulders, enlarged calves and heart problems. The MDA notes that, although there are numerous complications associated with BMD, BMD is usually much less severe than other muscular dystrophies, including Duchenne muscular dystrophy.
