A Computer room full of printers, disk drives, and monitors would be still and silent without the central processor itself. Likewise, the body would be lifeless without the brain. The human brain has three main parts. The top part, making up nine-tenths of the brain's volume, is the wrinkled cerebrum. This is the thinking part of the brain. The back part of the brain is the cerebellum, a "mini brain" that deals mainly with balance, posture, and skilled movements. All of the other areas of the brain(including the pons, thalamus, medulla, and hypothalamus shown below) belong to a part of the brain called the brain stem. This joins with the spinal cord below it and the cerebrum above it.