what is the cortex?
Share. The cerebral cortex is the layer of the brain often referred to as gray matter. The cortex (thin layer of tissue) is gray because nerves in this area lack the insulation that makes most other parts of the brain appear to be white. The cortex covers the outer portion (1.5mm to 5mm) of the cerebrum and cerebellum. The portion of the cortex that covers the cerebrum is called the cerebral cortex. The cerebral cortex consists of folded bulges called gyri that create deep furrows or fissures called sulci.