The Basal Vein of Rosenthal. E, Lateral view of the right tentorial incisura, in a different specimen. The temporal lobe has been removed to expose the basal vein. Both the anterior peduncular (anterior anastomotic vein) and the mesencephalic segment (posterior anastomotic veins; blue shaded areas) are absent, and the striate, peduncular, and mesencephalic segments of the basal vein are disconnected from each other. The striate segment drains inferiorly via the anterior pontomesencephalic vein; the peduncular segment drains inferiorly through a prominent lateral mesencephalic vein; and the tributaries of the mesencephalic segment drain directly into the vein of Galen. F, Inferior view of the right basal vein. The anterior peduncular segment (anterior anastomotic vein) of the basal vein is hypoplastic. As a consequence, the inferior ventricular vein empties into and forms the posterior peduncular and mesencephalic segments of the basal vein, and the anterior segment of the basal vein drains anteriorly. A prominent lateral atrial vein drains into the mesencephalic segment. G, Left paramedian infratentorial supracerebellar approach to the tectal region and lateral mesencephalic sulcus. A hypoplastic mesencephalic segment (posterior anastomotic vein) is identified. The basal vein drains inferiorly through a prominent lateral mesencephalic vein. H, Left internal carotid artery angiogram, venous phase, lateral projection. A fragmented basal vein is identified. The anterior peduncular segment is hypoplastic, and the anterior segment of the basal vein drains anteriorly through the preuncal vein. The middle segment of the basal vein drains inferiorly into the superior petrosal sinus through a prominent lateral mesencephalic vein and the posterior (mesencephalic) segment of the basal vein drains posteriorly into the vein of Galen. (Images courtesy of AL Rhoton, Jr.)