M, The occipital transtentorial is directed along the medial surface of the occipital lobe below the lambdoid suture. This occipital lobe below the lambdoid suture is commonly free of bridging veins to the superior sagittal sinus, making it a reasonable route for the occipital transtentorial approach. N, There are no large bridging veins between the posterior 6 cm of the occipital lobe and superior sagittal sinus. The first vein encountered is the internal occipital vein that passes from the anterior part of the medial occipital lobe to the vein of Galen. O, The vein of Galen has been retracted to expose the splenium and pineal from above. P, The tentorium has been opened lateral to the straight sinus, and the vein of Galen has been displaced to the left side to expose the pineal and the superior and inferior colliculi. Q, Elevating the branches of the vein of Galen provides a satisfactory view into the quadrigeminal cistern, with a better view into the cerebellomesencephalic fissure than can be achieved with the infratentorial supracerebellar approach directed over the apex of the tentorial cerebellar surface. R, The exposure has been directed laterally along the side of the brainstem to the ambient cistern where the lateral margin of the cerebral peduncle is exposed. (Images courtesy of AL Rhoton, Jr.)