Diagram showing the various structures of the brain and their position within the skull. The diagram shows the main part of the brain known as the cerebrum which is covered by the meninges. The four layers of the meninges are the dura mater, the arachnoid, the sub-arachnoid space and the pia mater, which is closest to the cerebrum. Extending from the centre of the brain to the spinal cord is the brain stem. At the back of the brain is the cerebellum.