Thus in contemporary discussions of the accessory nerve, the common practice is to dismiss the cranial part altogether, referring to the accessory nerve specifically as the spinal accessory nerve.

May be obsoleted in future. WP states: Traditional descriptions of the accessory nerve divide it into two parts: a spinal part and a cranial part.[1] But because the cranial component rapidly joins the vagus nerve and serves the same function as other vagal nerve fibers, modern descriptions often consider the cranial component part of the vagus nerve and not part of the accessory nerve proper.

uberon

Cranial nerves XI and XII evolved in the common ancestor to amniotes (non-amphibian tetrapods) thus totalling twelve pairs.[well established][VHOG]

UBERON:0009673