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George E. Carvell, PhD, PT   University of Pittsburgh
SPINAL CORD: Dorsolateral Descending Pathway
The Dorsolateral Descending Pathway is a functional grouping of tracts located in the lateral funiculus. The two major tracts in this pathway are the Lateral CorticoSpinal Tract (LCST) and the RubroSpinal Tract (RuST); reticulospinal tract axons in the dorsolateral funiculus (DLF) are also located in this pathway (not shown). The major spinal gray matter targets for the LCST and the RuST are motoneurons and interneurons in the lateral motor nucleus of the ventral horn, 'short' propriospinal neurons in the intermediate gray. The LCST has a significant input to neurons in the substantia gelatinosa and nucleus proprius of the dorsal horn. This pathway projects to all levels but the majority of axons terminate in the cervical cord. This pathway is critical for fine motor control of the extremities, especially for reaching and grasping with the upper extremity, well regulated foot placement, and modulation of somatosensory inputs by the LCST and the DLF. Active touch, in particular, requires cooperation
of the ascending dorsal column medial lemniscus tract and the descending LCST. The DLF has a role in modulation of peripheral sensory input, autonomic function, and spinal reflexes.
   The LCST originates from Pyramidal Tract Neurons (PTNs) located in the Cerebral Cortical Motor Areas of the Frontal Lobe and in the Somatosensory Areas of the Parietal Lobe. The LCST is also known as the Crossed Pyramidal Tract
   The RuST originates from Projection Neurons in the Red Nucleus of the Midbrain Portion of the Brainstem.