A motor neuron is a type of nerve cell that transmits signals from the brain and spinal cord to muscles, enabling movement. These neurons play a crucial role in the nervous system by controlling voluntary actions, such as walking or grasping objects. Motor neurons can be classified into two main types: upper motor neurons, which originate in the brain, and lower motor neurons, which connect to muscles. Damage to motor neurons can lead to conditions like amyotrophic lateral sclerosis (ALS) or spinal muscular atrophy, resulting in muscle weakness and loss of movement.