View of the left hypoglossal canal and jugular foramen. For orientation, the bottom of the image is ventral, the left border is rostral, the top border is caudal, and the brainstem has been transected at the level of the rostral medulla. The posterior inferior cerebellar artery (PICA) arises from the intradural vertebral artery proximal to the vertebrobasilar junction and, in this image, courses laterally in close relationship to the glossopharyngeal (CNIX) and vagus (CNX) nerves near the jugular foramen. The hypoglossal nerve (CNXII) enters the hypoglossal canal superior to the occipital condyle. The facial and vestibulocochlear nerves (CN VII-VIII) (cut) are visible entering the internal acoustic meatus, as are the trigeminal (CNV) and abducens nerves (CNVI) entering their respective foramina. (Image courtesy of AL Rhoton, Jr.)