B: The innermost layer that contours closely to the many folds and crevices of the brain is called the pia mater. A: The arachnoid or arachnoid mater is the middle layer of the meninges. C: Dura mater is the outermost layer of the meninges. D: Tentorium cerebelli is an extension of the dura mater that separates the cerebellum from the inferior portion of the occipital lobes.