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 and involuntary actions, such as walking or reflexes. 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), resulting in muscle weakness and atrophy.