The parieto-occipital sulcus marks one point of demarcation between the parietal lobe and the occipital lobe. The other is a feature of the inferior aspect of the hemisphere called the pre-occipital _______ which is attributable to a flap of dura that sits between the cerebellum and the occipital lobe called the tentorium. So an imaginary line between the parieto-occipital sulcus and that pre-occipital () is what divides the parietal lobe from the occipital lobe