Tetraplegia is the result of an injury or disease, most often affecting the spine. Although a paraplegic has lost the use of only his legs, the quadriplegics are paralyzed in all four limbs. Today, voice-activated wheelchairs help quadriplegics get around, and homes can be equipped with similar systems to operate lights and appliances; monkeys were even trained to help quadriplegics with everyday tasks. The work of quadriplegic actor Christopher Reeve has led to remarkable advances in the development of new nerve connections, allowing some determined paraplegics and quadriplegics to walk again.

Tetraplegia, also known as tetraplegia, is paralysis caused by disease or injury resulting in partial or total loss of use of all four limbs and trunk; paraplegia is similar but does not affect the arms. Loss is usually sensory and motor, which means that both sensation and control are lost. Paralysis can be flaccid or spastic.