APA Dictionary of Psychology

any of four major descending groups of nerve fibers within the motor system, conveying information from diffuse areas of the cerebral cortex, midbrain, and cerebellum. These pathways include the anterior corticospinal tract, which descends directly from motor cortex to the anterior horn of the spinal cord; the vestibulospinal tract, which carries information from the vestibular nuclei for control of equilibratory responses; the tectospinal tract, for control of head and eye movements; and the reticulospinal tract, for maintaining posture.