The central nervous system consists of the brain and the spinal cord. The peripheral nervous system consists of the extensions of neural structures beyond the central nervous system and includes somatic and autonomic divisions.
The brain is composed of 3 main structural divisions: the cerebrum, the brainstem, and the cerebellum (see the images below). At the base of the brain is the brainstem, which extends from the upper cervical spinal cord to the diencephalon of the cerebrum. The brainstem is divided into the medulla, pons, and midbrain. Posterior to the brainstem lies the cerebellum.
Brain, coronal view.
Brain, inferior view.
Brain, lateral view.
Brain, midsagittal view.