Prolonged individuality of the accessory contribution to the vagus: A peculiarity of the pig

Abstract The bulbar and spinal components of the accessory nerve of the pig are thoroughly integrated in a common trunk at the jugular foramen. The fibers of bulbar origin separate from this trunk to form the internal ramus. The latter is especially demonstrable in the pig, since it is independent over a considerable distance in the upper part of the neck before joining the vagus. As far distally as the origin of the recurrent laryngeal nerve, the efferent fibers contributed to the vagus by the accessory nerve remain histologically separate from the afferent fibers belonging properly to the vagus. Parasympathetic, branchiomotor and afferent fibers can be distinguished in the vagal trunk without the necessity of inducing selective degeneration by supranodose vagotomy.