The major subdivisions of the brain are the prosencephalon, the mesencephalon, and the rhomencephalon. These are also referred to as the forebrain, midbrain, and hindbrain. These three divisions are even further divided into ventricles, subdivisions of ventricles and subsequent main structures.
The prosencephalon consists of the lateral ventricle and third ventricle. These two ventricles are further subdivided into the telencephalon and the diencephalon. From these two subdivisions the following main structures are defined: cerebral cortex, basal ganglia, limbic system, thalamus and hypothalamus.
The mesencephalon is comprised of the cerebral aqueduct that is made of a subdivision known as the mesencephalon. This subdivision contains two main structures called the tectum and the tegmentum.
The third major subdivision of the brain, the Rhombencephalon, contains a ventricle simply named the fourth ventricle. This ventricle is made up of the metencephalon and the myelencephalon. These two subdivisions contain three main structures: the cerebellum, pons and medulla oblongata.
These three main subdivisions the brain form at different periods through the development of the embryo. Portions of the brain that control more primitive aspects of all mammals in the animal kingdom are formed first. Following this development, more refined aspects of the human brain begin to formulate. It is with the help of these highly refined anatomical features that the human brain is differentiated from other species.