What are Motor Neurons?
Motor neurons are a type of nerve cell that directly or indirectly control muscle movements. They are essential components of the
nervous system, forming a critical link between the central nervous system (CNS) and muscles. Motor neurons are responsible for converting electrical signals from the brain and spinal cord into
muscle contractions.
Upper motor neurons (UMNs): These neurons originate in the motor cortex of the brain and travel down the spinal cord. They are involved in the initiation and control of voluntary movements.
Lower motor neurons (LMNs): These neurons originate in the spinal cord and directly innervate skeletal muscles. They are responsible for executing the movements initiated by the UMNs.
Cell body: Also known as the soma, it contains the nucleus and is the metabolic center of the neuron.
Dendrites: These are branched extensions that receive electrical signals from other neurons.
Axon: A long, slender projection that transmits electrical impulses away from the cell body toward the muscles.
Axon terminals: The end points of the axon that form synapses with muscle fibers.
Myelin sheath: A fatty layer that surrounds the axon, speeding up the transmission of electrical signals.
Nissl staining: This method highlights the cell body and dendrites, making it easier to study the neuron's structure.
Immunohistochemistry: This technique uses antibodies to identify specific proteins within the motor neurons, allowing for the study of their function and pathology.
Fluorescence microscopy: This imaging method uses fluorescent dyes to visualize motor neurons in high detail.
Amyotrophic lateral sclerosis (ALS): A progressive neurodegenerative disease that affects both upper and lower motor neurons, leading to muscle weakness and atrophy.
Spinal muscular atrophy (SMA): A genetic disorder that primarily affects lower motor neurons, causing muscle weakness and wasting.
Poliomyelitis: A viral infection that can damage motor neurons, leading to paralysis.
