The anterior corticospinal tract is formed by the remaining descending upper motor neurons that did not decussate in the caudal medulla to form the lateral corticospinal tract. These upper motor neurons, which remain ipsilateral to form the anterior corticospinal tract, descend through the medial aspect of the anterior spinal cord to the level of the upper thoracic region (eFig. 9.54). These axons project bilaterally to synapse on cell bodies of lower motor neurons in the medial portion of the anterior horn gray matter. Axons of these lower motor neurons then exit the spinal cord through the anterior root.