Myopathy

Myopathy is a disease of the muscle in which the muscle fibers do not function properly. 
This results in muscular weakness. "Myopathy" simply means muscle disease (Greek myo- "muscle" + patheia &lt; -pathy "suffering"). This meaning implies that the primary defect is within the muscle, as opposed to the nerves ("neuropathies" or "neurogenic" disorders) or elsewhere (e.g., the brain). Muscle cramps, stiffness, and spasm can also be associated with myopathy.
Muscular disease can be classified as neuromuscular or musculoskeletal in nature. Some conditions, such as myositis, can be considered both neuromuscular and musculoskeletal.