n. The tenth cranial nerve, or wandering nerve, the longest and most widely distributed of the nerves of the brain, extending through the neck and thorax to the upper part of the abdomen.n. In insects, the principal visceral or stomatogastric nerve, which originates in two parts in the head, beneath the bases of the antennæ, uniting in a ganglion below the cerebrum, and passing backward along the upper surface of the intestinal canal.