These are motor tracts that carry motor commands to the lower brain structures and spinal cord and eventually to the muscles and glands. All descending tracts originate in the motor cortex. The corticospinal fibers decussate in the lower part of the medulla to form the large lateral corticospinal tract on the opposite side of the spinal cord. A smaller portion of the corticospinal fibers continue on the same side to form the anterior corticospinal tract . Both fiber tracts serve the muscles of the torso and extremities.
Corticothalmic fibers carry information from the cerebral cortex to the thalamus.
Cortico-rubral fibers terminate in the upper midbrain structure of red nucleus . Corticopontine fibers terminate in the ventral pons. Cortico-olivary fibers terminate in the upper part of the medulla. Corticobulbar fibers terminate variously in the brainstem structures of midbrain, pons and medulla. All sensory information except olfactory sensation is projected to the primary sensory areas of the cortex by way the thalamocortical fibers .