part of start stage end stage caudal root of abducens nerve ZFA:0000179 radix caudalis nervi abducentis Cranial nerve root which is part of the abducens nerve (CN-VI) and is located at the level of the intermediate reticular formation. Fuses with the rostral root of the abducens nerve and courses rostrally once outside the brain stem. From Neuroanatomy of the Zebrafish Brain. zebrafish_anatomy TAO:0000179 cranial nerve VI medulla oblongata cranial nerve root unknown adult