The cerebellum is a small section of the brain that sits in back, next to where the spinal cord attaches to the brain. Although the cerebellum constitutes only about 10% of the brain by volume, it contains nearly 80% of the brain's neurons. This part of the brain is especially important for the integration of sensory perception and motor output. The cerebellum monitors the position of the body and communicates with the motor cortex to fine-tune the signals sent to the muscles. People who have damage to their cerebellum show problems with coordination and movement. The cerebellum is also important for the cognitive functions of attention, language, music and other sensory tasks.