upper motor neuronemedical dictionary

Clinical term indicating those neurone's of the motor cortex that contribute to the formation of the pyramidal or corticospinal and corticobulbar tracts, as distinguished from the lower motor neurone's innervating the skeletal muscles. Although not motor neurone's in the strict sense, these cortical neurone's became colloquially classified as motor neurone's because their stimulation produces movement and their destruction causes severe disorders of movement.

See: motor neurone, motor cortex.

American spelling: upper motor neuron

(05 Mar 2000)