a fiber bundle originating in the fastigial nucleus (nucleus tecti) of both sides, passing out of the cerebellum in the medial portion of the inferior cerebellar peduncle (corpus juxtarestiforme), and distributing its fibers to the vestibular nuclei and other cell groups in the medulla oblongata. Prominent crossed fibers loop over the surface of the superior cerebellar peduncle before turning anteriorly (ventrally), forming the uncinate bundle of Russell. SYN: tractus fastigiobulbaris.