Damage to the musculoskeletal system can occur from many sources, including illness or infection, trauma, age-related changes, and congenital defects. Some people are born with a physical deformity of their muscles or bones, such as microcephaly or hydrocephalus. These conditions are called developmental disorders because they arise during childhood development process. When muscles or bones are damaged, it can lead to disability or even death if appropriate treatment is not given.