The human body has more than 600 muscles. Many of these are skeletal muscles—you can move them voluntarily and control what they do. Together, the skeletal muscles and the bones give your body the power and strength to move.
Muscular dystrophy is a group of more than 30 diseases that involve breakdown of the skeletal muscles. When a child has muscular dystrophy, his muscle tissue weakens and wastes away.
Certain types of muscular dystrophy are present at birth, while others don’t start causing symptoms until middle age or later. Regardless of the age of onset, muscular dystrophy is always progressive—it continues to get worse over time.