|This article does not cite any references or sources. (May 2009)|
Lower motor neurons (LMNs) are the motor neurons connecting the brainstem and spinal cord to muscle fibers, bringing the nerve impulses from the upper motor neurons out to the muscles. A lower motor neuron's axon terminates on an effector (muscle).
Lower motor neurons are classified based on the type of muscle fiber they innervate:
Glutamate released from the upper motor neurons triggers depolarization in the lower motor neurons in the ventral horn which in turn causes an action potential to propagate the length of the axon to the neuromuscular junction where acetylcholine is released to carry the signal across the synaptic cleft to the postsynaptic receptors of the muscle cell membrane, signaling the muscle to contract.
Damage to lower motor neurons, lower motor neuron lesions (LMNL) cause decreased tone, decreased strength and decreased reflexes in affected areas. These findings are in contrast to findings in upper motor neuron lesions. LMNL is indicated by abnormal EMG potentials, fasciculations, paralysis, weakening of muscles, and neurogenic atrophy of skeletal muscle.
|This neuroanatomy article is a stub. You can help Wikipedia by expanding it.|
Contenido de sensagent