The tentorium cerebelli is the second largest dural reflection in the skull, after the falx cerebri. It lies transverse, separating the occipital lobes from the cerebellum and providing the key landmark for separating the brain into the supratentorial and infratentorial brain regions. Though many would disagree, it is often described as “crescent-shaped.” It attaches anteriorly at the clinoid processes (clinoid in Greek is “bed-like”) and attaches at the back of the occipital bone.