What is the lower motor neuron?
The lower motor neuron (LMN) is the efferent neuron of the peripheral nervous system (PNS) that connects the central nervous system (CNS) with the muscle to be innervated. The entire function of the CNS is manifested through the lower motor neuron.
Where is lower motor neuron located?
Skeletal (striated) muscle contraction is initiated by “lower” motor neurons in the spinal cord and brainstem. The cell bodies of the lower neurons are located in the ventral horn of the spinal cord gray matter and in the motor nuclei of the cranial nerves in the brainstem.
What is a LMN injury?
A lower motor neuron (LMN) injury can result from a cauda equina injury or conus injury. In the lumbar region of the spine, there is a spray of spinal nerve roots called the cauda equina.
What is the difference between upper motor neuron and lower motor neuron?
The upper motor neurons originate in the cerebral cortex and travel down to the brain stem or spinal cord, while the lower motor neurons begin in the spinal cord and go on to innervate muscles and glands throughout the body.
What is LMN lesion?
A lower motor neuron lesion is a lesion which affects nerve fibers traveling from the lower motor neuron(s) in the anterior horn/anterior grey column of the spinal cord, or in the motor nuclei of the cranial nerves, to the relevant muscle(s).
Is spinal cord UMN or LMN?
The nerves that lie within the spinal cord are called UMNs, and they carry messages back and forth from the brain to the spinal nerves along the spinal tract. Injury to the upper motor neurons results in a loss of coordinated and integrated control of reflex activity below the level of injury.
Where lower motor neurons start?
The upper and lower motor neurons form a two-neuron circuit. The upper motor neurons originate in the cerebral cortex and travel down to the brain stem or spinal cord, while the lower motor neurons begin in the spinal cord and go on to innervate muscles and glands throughout the body.
How is the lower motor neuron activated?
Glutamate released from the upper motor neurons triggers depolarization in the lower motor neurons in the anterior grey column, 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 …