Images

Spinal muscular atrophy (SMA) is a group of inherited disorders characterized by a loss of certain nerve cells called motor neurons. Motor neurons transmit nerve impulses from the brain or spinal cord (brainstem) to muscle or glandular tissue. The loss of motor neurons leads to progressive muscle weakness and muscle wasting (atrophy) in muscles closest to the trunk of the body (proximal muscles) such as the shoulders, hips and back. (NORD)