The distinct pathway and controversial morphology of cranial nerve XI (spinal accessory nerve) make it unique among the cranial nerves. In the past decade, several anatomical and embryological studies have further elucidated the structure and function of CN XI. In this review, the evolutionary history of CN XI and its phylogenetic relationship to CN X, the vagus nerve, are considered in light of these recent investigations to provide a fuller anatomical picture of the CN XI. Implications for anatomical education are also considered.