Lower Motor Neuron

A lower motor neuron (often abbreviated LMNs) is the part of a motor neuron (a type of nerve cell) that connects the brainstem and spinal cord (via the upper motor neurons) to the skeletal muscles. The brainstem is an area in the lower part of the brain that connects it with the spinal cord. Skeletal muscles are muscles that are connected at either or both arms or legs with the skeleton of the body. Upper motor neurons are nerve cells in the motor cortex (an area of the brain located in middle, top part of the brain) that help make up nerve paths within the brain and from the brain to the spine.

Lower motor neurons are present in the spinal nerves, peripheral nerves (nerves outside of the brain or spinal cord), and anterior horn cells. Anterior horn cells are types of cells located in the spinal cord. Damage to lower motor neurons can cause lower motor neuron paralysis, in which loss of movement/and or sensation can occur in addition to a loss of certain reflexes and the occurrence of various other signs and symptoms such as decreased muscle tone, weakness, fasciculations (small involuntary muscle contraction), decreased reflexes, and muscles atrophy.