Dissection presents a ventral view of the brainstem in situ showing its associated neurovascular relationships. The sella turcica, portions of the petrous temporal bone, hypoglossal canals, foramen magnum, and a strip of dura mater remain for orientation. The vertebral arteries, after passing through the foramen magnum, join to form the basilar artery on the ventral surface of the pons. Here, in addition to several pontine branches, it gives rise to the anterior inferior cerebellar and superior cerebellar arteries before terminating as the right and left posterior cerebral arteries. Note the emergence of the oculomotor nerve between the posterior cerebral and superior cerebellar arteries. Note also the lengthy course of the abducens nerves deep to the dura mater overlying the clivus (removed) and then just lateral to the internal carotid artery in the cavernous venous sinus. The facial and auditory nerves can be seen entering the internal auditory meatus and the glossopharyngeal, vagus, and spinal accessory nerves coursing toward the jugular foramen. The hypoglossal nerve can be observed traversing its hypoglossal canal to enter the neck. (Image courtesy of AL Rhoton, Jr.)