You can divide brain in to three different 'bigger' structures: brain stem, cerebellum and cerebrum. Brain has developed from the inside out, meaning brainstem and cerebellum are the most primitive part of our brain. The cerebrum is the part of the human brain that holds the key for our highly developed cognitive skills, such as memory, perception, and the ability to think etc.
The brainstem is composed of three parts: medulla oblongata, pons and midbrain. Brainstem mostly controls the very primal abilities like sleep, breath, blood pressure, muscle contractions that keep up our body heat and other autonomic functions. Brainstem also connects spinal cord and cerebellum to our brain.
The cerebellum is responsible for the body's balance, posture, and the coordination of movement. Cerebellum also has it's own cerebellar cortex.
The cerebrum is composed of the following sub-regions: limbic system, basal ganglia and the cerebral cortex.
The cerebrum has two hemispheres, left and right. They are almost completely separate from each other, corpus callosum is basically the only structure in cerebrum that keeps the two hemisphere connected to each other. With the assistance of the cerebellum, the cerebrum controls all voluntary actions in the body.
