Every year, more than 10,000 people in the United States suffer traumatic injury to their spinal cord. Such injury can stem from falls, car crashes and diving accidents, among other incidents. Spinal cord trauma can cause damage to nerve roots and grey matter (the cell bodies of nerves) that in turn adversely impacts neural messaging to and from the brain and, ultimately, functions like breathing and walking. A complete spinal injury is sustained when there is neither movement nor sensation below the injury and both sides of the body are affected equally; an incomplete spinal injury occurs when there is some movement or sensation below the injury. Paralysis resulting from spinal cord injury is categorized as quadriplegia, involving the arms, trunk, pelvic organs and legs, or paraplegia, when all or part of the legs, pelvic organs and trunk are affected.