pyramidal tract
the primary pathway followed by motor neurons that originate in the motor area of the cortex, the premotor area, the somatosensory area, and the frontal and parietal lobes of the brain. Fibers of the pyramidal tract communicate with fibers supplying the peripheral muscles. Because of the contralateral relationship between left and right brain hemispheres and motor activity on the opposite sides of the body, pyramidal-tract fibers cross in the pyramids of the medulla oblongata. The pyramidal tract includes the corticospinal tract, and the two terms are occasionally used synonymously. Also called pyramidal motor system; pyramidal system. See also extrapyramidal tract.