Midline Supracerebellar Perspective of the Pineal Region. The internal cerebral vein can be seem projecting posteriorly to join the vein of Galen. The basal veins of Rosenthal convene on the vein of Galen from a lateral direction. The vein of the cerebellomesencephalic fissure can be seen in the midline obscuring the pineal gland and represents an obstical to the pineal region during a midline approach. (Image courtesy of AL Rhoton, Jr.)