Human brain. Coloured historical illustration of the human brain, seen in side view. At top are surface folds and convolutions of the left cerebral hemisphere. The cerebrum is the largest most developed part of the brain, responsible for conscious thought, sensation and memory. Behind and beneath it is the smaller cerebellum (centre right). The cerebellum region of the hindbrain is rounded, comprises about 11% of brain weight, and is concerned with posture, balance, and muscle coordination. The spinal cord is part of the central nervous system, is enclosed within the vertebrae, and serves to transmit nerve impulses from the brain to the body and vice versa.