What Protects the Brain?

The brain is protected by connected bony plates in the head known as the skull. It is also protected by the meninges, a three layer membrane.

The human skull has 22 bones. Eight bones enclose the brain and make up the cranium. These are the occipital bone, which is found at the back of the skull, and the sphenoid, which is found at the base of the skull. There are two parietal bones at the top and sides of the skull. The frontal bone is found at the forehead and the ethmoid bone is found at the nose. The other bones of the skull are the facial bones. In an adult, the bones unite in hard, zigzag joints called sutures. In babies, these places are still open and soft.

The meninges are divided into the dura mater, the pia mater and the arachnoid. The dura mater is the toughest of the membranes and lies just beneath the skull. It separates the two brain hemispheres from each other and the cerebellum. The arachnoid lies just beneath the dura mater and is separated from it by cerebrospinal fluid. The pia mater follows the folds and depressions in the brain. It contains blood vessels that bring blood to and from the cerebral cortex.