The anterior horn of the spinal cord is a column of grey matter containing a type of nerve cell called alpha motor neurons. Motor neurons are responsible for muscle control and movement and contrast with sensory neurons which are responsible for transmitting sensory information to the brain.
Nerve cells of the spinal anterior horn form part of the motor pathways. All peripheral motor nerves (the efferent nerves) originate in the anterior horn.
Although multiple sclerosis is predominately a disease of the white matter, damage to the white matter that connects to the anterior horn causes apparent muscle weakness (asthenia).
Amyotrophic Lateral Sclerosis (ALS) is the degeneration of the motor neurons in the brain and spinal cord especially those in the anterior horn.
Anterior horn links:
Multiple Sclerosis Glossary: A