<P> The brainstem at large provides entry and exit to the brain for a number of pathways for motor and autonomic control of the face and neck through cranial nerves, and autonomic control of the organs is mediated by the tenth cranial (vagus) nerve . A large portion of the brainstem is involved in such autonomic control of the body . Such functions may engage the heart, blood vessels, pupillae, among others . </P> <P> The brainstem also hold the reticular formation, a group of nuclei involved in both arousal and alertness . </P> <P> The cerebellum lies behind the pons . The cerebellum is composed of several dividing fissures and lobes . Its function includes the control of posture, and the coordination of movements of parts of the body, including the eyes and head as well as the limbs . Further it is involved in motion that has been learned and perfected though practice, and will adapt to new learned movements . Despite its previous classification as a motor structure, the cerebellum also displays connections to areas of the cerebral cortex involved in language as well as cognitive functions . These connections have been shown by the use of medical imaging techniques such as fMRI and PET . </P> <P> The body of the cerebellum holds more neurons than any other structure of the brain including that of the larger cerebrum (or cerebral hemispheres), but is also more extensively understood than other structures of the brain, and includes fewer types of different neurons . It handles and processes sensory stimuli, motor information as well as balance information from the vestibular organ . </P>

Is the cerebellum part of the nervous system