The vagus nerve (pronounce /ˈveɪˌgəs/) (VĀ-gəs) (also called pneumogastric nerve or cranial nerve X) is the tenth of twelve paired cranial nerves, and is the only nerve that starts in the brainstem (within the medulla oblongata) and extends, through the jugular foramen, down below the head, to the neck, chest and abdomen, where it contributes to the innervation of the viscera.