Which area of the dura separates the cerebral hemispheres from the cerebellum?

The correct answer is the tentorium. The tentorium cerebelli is a horizontal fold of the dura mater that separates the cerebellum from the occipital lobes of the cerebrum. This structure plays a crucial role in compartmentalizing the intracranial space and helps prevent the potentially damaging movement of brain structures against each other, particularly during changes in head position or during traumatic events.

The falx cerebri, in contrast, is a vertical fold of dura that separates the left and right cerebral hemispheres. The diaphragma sellae is another dura mater structure that forms a roof over the sella turcica of the sphenoid bone, enclosing the pituitary gland but does not separate the hemispheres from the cerebellum. The term "fascia of the brain" does not refer to a specific anatomical structure recognized in cranial anatomy and is not relevant to the separation of the cerebral hemispheres from the cerebellum. Thus, the tentorium is the key structure that serves this purpose effectively.