Brainy Facts. The average adult brain weighs about 1,600g in men and 1,450 in womenThe size is proportional to intelligence The surface area of the brain would cover about 4.5 notebook pages (1/3 that w/o folds). The Meninges. There are three levels of connective tissue that enclose the CNS. They serve as protection for the brain and spinal cord.The three layers from superficial to deep are the.Dura MaterArachnoid Mater Pia Mater.