A Tour of the Brain

The Editors September 19, 2026 2 min read

A guided walk from the bottom of the brain to the top: brainstem, cerebellum, the deep structures of the forebrain, and the folded cerebral cortex — with what each part is best known for.

In plain English

The brain has three big parts: the brainstem at the bottom, which keeps you alive; the cerebellum at the back, which coordinates movement; and the large, wrinkled cerebrum on top, which handles senses, thinking, language and voluntary action. Deep inside are smaller structures for memory, emotion and relaying signals.

Beginner level: No background needed. Everyday language, everyday examples — the place to start.

The human brain is often described in three big parts — brainstem, cerebellum and cerebrum — plus a set of deep structures tucked inside. A good way to learn them is to tour from the bottom up, roughly following the order in which they evolved and develop.

The brain cut down the middle (a sagittal view), showing the brainstem, cerebellum, thalamus, hypothalamus, corpus callosum and cortex. (tap to enlarge)

The brainstem: life support

Continuous with the spinal cord, the brainstem has three parts: the medulla, pons and midbrain. It controls breathing, heart rate, blood pressure, swallowing and the sleep-wake cycle, and it carries every signal passing between brain and body. Most cranial nerves connect here. Damage to the brainstem is often life-threatening.

The cerebellum: the coordinator

Tucked behind the brainstem, the cerebellum ("little brain") fine-tunes movement, balance and timing, and plays a role in some kinds of learning and thinking. It holds about 80% of the brain's neurons.

The deep forebrain

Above the brainstem sits the thalamus, a relay station for almost all sensory information on its way to the cortex. Below it, the small hypothalamus controls hormones, hunger, thirst, body temperature and daily rhythms. Around them are the basal ganglia (action selection and habits), the hippocampus (memory and navigation) and the amygdala (emotional significance, especially threat).

The cerebrum and cortex

The cerebrum is the largest part, split into left and right hemispheres joined by the corpus callosum. Its outer layer, the cerebral cortex, is a folded sheet a few millimetres thick, divided into four lobes on each side — frontal, parietal, temporal and occipital — plus the hidden insula. Beneath the grey cortex lies the white matter: the brain's cabling.

Protected and floating

The brain is wrapped in three membranes, the meninges, and cushioned by cerebrospinal fluid, in which it effectively floats. Its consistency is surprisingly soft — often compared to firm tofu or custard.

Make it simple

Everyday examples & things to try

Try it

Your fist as a brain model

The psychiatrist Dan Siegel popularised this 'hand model': make a fist with your thumb tucked inside. Your wrist is the spinal cord, the base of your palm the brainstem, your thumb the deep limbic structures, and your curled fingers the cortex wrapped over the top — with the front of the brain at your fingernails. It's rough, but it captures the layout.

Key takeaways

Brainstem (medulla, pons, midbrain): life support and the brain-body highway.
Cerebellum: coordination and timing; most of the brain's neurons.
Cerebrum: two hemispheres with a folded cortex, plus deep structures like the thalamus, hippocampus and amygdala.

Explore further

Search YouTube for…

Tap a phrase to copy it, then paste it into YouTube's search box. This site doesn't link to other websites — pick channels from universities, hospitals and established science educators.

Tagsanatomyoverviewbasics

About this project

NeuroScience Decoded is an independent, plain-language encyclopedia of the brain and nervous system. It covers what neuroscience is, five thousand years of its history and the people who made it, how neurons and synapses work, brain chemistry and anatomy, development, the senses, movement, memory, emotion, sleep and consciousness, neurological and mental health conditions, the tools scientists use, the overlap with artificial intelligence, treatments, and the ethics and future of the field.

Every entry is written to be understood by a curious reader with no science background. Each one is tagged Beginner, Intermediate or Advanced, opens with an In plain English summary, offers everyday analogies and try-it-yourself examples, ends with key takeaways, and links to the concepts worth reading first.