A second spinocerebellar system is present but differs from the first in two respects. The first is that it is crossed and the second is that it appears to be utilized for the coordination of gross movement that involves many muscles and one or more joints. Second order neurons of the dorsal horn that were activated by groups Ia, Ib, and  II axons cross to the opposite side of the spinal cord via the anterior white commissure. The axons of these second order neurons form the anterior spinocerebellar tract. The tract is derived from cells in the midthoracic region and below (lower trunk and legs). The tract is somatotopically organized and passes through the medulla to enter the cerebellum via the superior cerebellar peduncle.