A Nerve of McKenzie With a Variant Communicating Branch Between the Vagus Nerve and Cranial Root of the Accessory Nerve: A Cadaveric Case Report

Anatomical variations of the craniocervical junction including a nerve of McKenzie, a branch between the spinal accessory nerve (XI) and the ventral root of the first cervical nerve (C1), have been identified. During routine dissection, a nerve of McKenzie with an interneural connection between the cranial root of the accessory nerve and the vagus nerve was observed on the left side. To our knowledge, a case with these two anatomical variations in the same cadaver and on the same side has not previously been reported. These variants may complicate surgery of the nerves of the craniocervical junction, and should thus be appreciated by the surgeon. Here, we discuss this case, its possible embryological origins, and the clinical significance.