When you see a patient, or an exam scenario, one of the first questions you will ask yourself is: Is the lesion in the CNS or the PNS? If the signs and symptoms point to one or more of the three long tracts being compromised, then you will be thinking about the CNS. The three long tracts are the: (1) corticospinal, (2) dorsal columns, and (3) spinothalamic. The corticospinal tract is a descending motor pathway, while both the dorsal columns and spinothalamic tracts are ascending sensory pathways. As these tracts travel to or from the cerebral cortex, all three decussate at some point in the CNS. What makes life complicated for students is that all three tracts cross at separate locations in the CNS.