Tentorium within the Brain, Superior View

Description

Seen from a superior perspective, the tentorium cerebelli forms a transverse dural fold separating the occipital lobes of the cerebrum superiorly from the cerebellar hemispheres inferiorly. Its free medial margin curves anteromedially to create the tentorial notch (incisura tentorii), through which the midbrain ascends, with the splenium of the corpus callosum and posterior diencephalon lying rostral to the opening in a typical male adult configuration. Laterally, the tentorium attaches to the superior border of the petrous part of the temporal bone and sweeps posteriorly toward the internal occipital protuberance, bracketing the transverse sinus within its attached margin and meeting the falx cerebri near the confluence of sinuses. Dura mater dominates the field. That notch matters. The incisura tentorii defines the corridor where transtentorial (uncal) herniation compresses the ipsilateral oculomotor nerve and the posterior cerebral artery, and where downward displacement can indent the midbrain (Kernohan notch) with false localizing hemiparesis. Neurosurgeons also use the tentorial edge as a fixed landmark when planning supracerebellar infratentorial approaches to pineal region tumors and when navigating venous anatomy around the straight sinus and vein of Galen, where a few millimeters can separate a clean corridor from a venous infarct. Neuroanatomy and neuropathology courses use this viewpoint to teach dural reflections, compartmentalization of the cranial cavity, and the logic of herniation patterns beyond rote “supratentorial versus infratentorial” labeling. It also fits well in operative atlases, radiology teaching files that correlate to axial MR/CT at the level of the tentorial leaflets, and patient education materials on brain swelling and mass effect. Anatomical accuracy verified by SciePro's Medical Advisory Board.