these include: 1) posterior external arcuate fibers [TA] that arise from cells in the accessory or lateral cuneate nucleus and pass to the cerebellum, and 2) anterior external arcuate fibers [TA] that arise from the arcuate nuclei at the base of the medulla oblongata and pass around the lateral surface of the medulla; both enter the cerebellum as components of the restiform portion of the inferior cerebellar peduncle. SYN: fibrae arcuatae externae.