Brain Structure And Cells

Functional Areas of human brain colour coded with labels for featured image

The brain has traditionally been seen as an anatomical structure of parts, lobes, and areas. Specialists will use these terms in diagnosis.


Three Parts

The cerebrum comprises the higher mental functions.

The cerebellum is the part at the back underneath the cerebrum that looks quite different with its tight winding structure. It’s responsible for motor functions.

The brainstem rises up from the bottom like a stem, going in front of the cerebellum and into the cerebrum, and connecting them to the spinal cord. The brain stem is made up of the midbrain, pons, and medulla oblongata. No brain stem, no life.

Illustration of cerebrum, cerebellum, and brain stem staff (2014). “Medical gallery of Blausen Medical 2014“. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010ISSN 2002-4436.

Four Lobes and the Cerebellum

The frontal lobe is located where its name says. It makes us who we are.

The parietal lobe sits behind the frontal lobe. It’s involved in speech and language, perception, and sensory functions.

The temporal lobe sits underneath the parietal one and behind the frontal lobe. It’s also involved in language as well as hearing and memory.

The occipital lobe sits at the back of the brain. It processes signals from the eyes and creates and interprets vision.

The cerebellum sits underneath the occipital and temporal lobes. It receives information from the sensory systems, the spinal cord, and other parts of the brain then regulates motor movements.

Coloured diagram of brain lobes

Deep fissures divide the lobes one from the other.

Functional Areas

There are too many identified areas to cover here. Some you may be familiar with include the thalamus, hypothalamus, hippocampus, corpus callosum, amygdala, prefrontal cortex, cingulate gyrus, and so on. A good place to begin is the Structure section on Wikipedia’s page Human Brain.

Functional areas of the brain in colour staff (2014). “Medical gallery of Blausen Medical 2014“. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010ISSN 2002-4436.



Illustration of a neuron in pink with an inset of microglia illustration in blue
The neuron is the cell we most commonly think of as comprising the brain. Medical gallery of Blausen Medical 2014″. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436., CC BY 3.0, via Wikimedia Commons

Neurons are the basic cell of the brain. They receive messages and transmit messages to other neurons via action potentials down their long arms called “axons.” Axons can be as long as across the brain or as short as micrometers. (If a long axon is broken in brain injury, replacing that length is why it takes time to re-establish.) They talk to each other across spaces called “synapses” via chemicals called “neurotransmitters.” Neurotransmitters include dopamine, serotonin, norepinephrine, GABA, and so on. These neurotransmitters can either cause the next neuron(s) to fire or to be quiet. Myelin sheathes speed up transmission of these messages. Bundled together, neurons form neural networks.


Illustrations of six different kinds of brain cells
The Central Nervous System, that is, brain and spinal cord, includes ependymal cells, oligodendrocytes, astrocytes, and microglia. Medical gallery of Blausen Medical 2014″. WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436., CC BY 3.0, via Wikimedia Commons

Glial cells include astrocytes, ependymal cells, oligodendrocytes, and microglia.


Astrocytes outnumber neurons by five to one. They perform many tasks from supporting axons and synapses to controlling the blood-brain barrier and blood flow.

Ependymal Cells

Ependymal cells form the lining of the brain’s ventricles and its aqueducts where cererbrospinal fluid (CSF) is produced and transported. The brain floats in the CSF, and the CSF provides a healthy environment for the brain.


Unlike the other glial cells, which arise out of stem cells for the nervous system, microglia are the brain’s immune cells. They nourish neurons, prune synapses during healthy development, and repair neurons. But when activated by infection, stress, or injury, they create neuroinflammation. Discussed in detail on the What Is Brain Injury? page.


Oligodendrocytes produce the myelin sheath that encases axons in a fatty insulation made from cholesterol. Myelin sheathes speed up the electrical conductance of axons by allowing the action potential to “jump” from gap to gap between the sheathes. These sheathes look white, hence the term “white matter” for parts of the brain containing these neurons. Grey matter comprises neurons without myelin sheathes. The destruction of these sheathes is what happens in MS (multiple sclerosis) and brain injury, and so oligodendrocytes are an important part of neuronal repair.

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