Anterior view of the brainstem (English)

Along its ventral surface, the midbrain is characterized by two prominences known as the cerebral peduncles which connect the cerebral hemispheres to the brainstem. Between each cerebral peduncle is a shallow depression, the interpeduncular fossa; the posterior perforated substance forms the floor of this fossa, while its contents include the oculomotor nerves (CN III) and mammillary bodies. The pons is limited superiorly by the pontomesencephalic sulcus (superior pontine sulcus) and ends inferiorly at the medullopontine sulcus (inferior pontine sulcus). When viewed from the ventral aspect, the pons resembles a dome-like structure with numerous horizontal striations across its surface. A shallow depression runs along its vertical axis known as the basilar groove, which houses the basilar artery. The trigeminal nerve (CN V) emerges from the lateral aspect of the pons while the abducens (CN VI), facial (VII) and vestibulocochlear nerve (CN VIII) arise from the medullopontine (inferior pontine) sulcus. The anterior median fissure divides the ventral medulla oblongata into symmetrical halves and is bordered on either side by the medullary pyramids. Lateral to each pyramid is another prominent bulge, the olive, which corresponds to the location of the olivary nuclei. At its caudal/inferior end, the anterior median fissure is interrupted by criss-crossing fibres known as the decussation of pyramids, which mark the termination of the medulla oblongata. The lower four cranial nerves (CN IX-XII) emerge from the anterior surface of the medulla oblongata.