spinal tract, any one of the ascending (sensory) and descending (motor) pathways for sensory or motor nerve impulses that is found in the white matter of the spinal cord. Twenty-one different tracts lie within the dorsal, ventral, and lateral funiculi of the white substance. Ascending tracts conduct impulses up the spinal cord to the brain; descending tracts conduct impulses down the cord from the brain. The four major ascending tracts are the lateral spinothalamic, the ventral spinothalamic, the fasciculi gracilis and cuneatus, and the spinocerebellar. The four major descending tracts are the lateral corticospinal, the ventral corticospinal, the lateral reticulospinal, and the medial reticulospinal. Touch, pressure, proprioception, temperature, and pain are sensory stimuli transmitted via the spinal tracts. Reflex and voluntary motor activity is regulated by motor nerve stimulation from the brain and brainstem to the motor neurons of the spinal cord.
