Lateral funiculus:

one of the three major subdivisions of white matter in the spinal cord, the lateral funiculi contain various ascending and descending tracts. Important pain pathways, like the spinothalamic tract, are found here as well as the lateral corticospinal tract, an important descending pathway for voluntary movement.

Learn more: Know your brain - Spinal cord

Watch this 2-Minute Neuroscience video to learn more about the spinal cord.