lower motor neuron paralysis

lower motor neuron paralysis,

paralysis resulting from an injury or lesion that damages the cell bodies or axons, or both, of the lower motor neurons, which are located in the anterior horn cells of the spinal cord and the spinal and peripheral nerves. If complete transection of the spinal cord occurs, voluntary muscle control is totally lost. In partial transection, function is altered in varying degrees, depending on the areas innervated by the nerves involved. In lower motor neuron paralysis the reflex arcs are permanently damaged, causing decreased muscle tone and flaccidity, diminished or absent reflexes, absence of pathologic reflexes, local twitching of muscle groups (fasciculations), and progressive atrophy of the atonic muscles. Compare upper motor neuron paralysis.