Did You Know? The human brain is the only thing in the world to name itself!

That three pounds of thinking inside your skull may be 60% fatty tissue but it’s far from lazy. Within its cranial confines, roughly 86 billion neurons form more than a trillion connections, sending information zipping through your body on electrical impulses that can travel faster than 250mph and power a 25-watt bulb.

The human brain is a mysterious machine and many of its secrets are yet to be unlocked, but here’s a quick anatomical breakdown of the brain, as we know it today.

The Parts of the Brain: Meninges, Cerebrum, Brainstem, Cerebellum

The Meninges

Before you can get to the brain itself, you’ll find the meninges, a layered covering that encases the brain and the spinal cord, both protecting them and supplying blood flow. The meninges has three layers, each playing an important role.

• Dura mater: This is the toughest, thickest and outermost layer of the meninges. The dura mater lines the inner dome of the skull, creating its own layered cushion of protected space for crucial blood vessels to the brain.


• Arachnoid mater: This membranous tissue does not actually contain nerves or blood vessels but helps to contain the cerebrospinal fluid that insulates the entire central nervous system and removes dangerous impurities.


• Pia mater: Dense with arteries and veins, this innermost layer of the meninges reaches into every wrinkle and groove of the surface of the brain, supplying necessary blood flow.

The Cerebrum

Located towards the front of the brain, the cerebrum is the largest part of the brain and the one most responsible for making humans what they are. The cerebrum is what makes us capable of speech, reason, emotion, learning, problem-solving, and just about all higher thought. If that weren’t enough, the cerebrum also contributes to basic sense functions, such as vision, hearing and interpreting touch.

The cerebrum is home to the cerebral cortex, amygdala, thalamus, hypothalamus, and hippocampus.

• Cerebral cortex: The largest part of the cerebrum, this is the highly recognizable outer grey matter of the brain, covered in the signature wrinkles and folds. It is divided into two hemispheres—left and right—that communicate through a dense nerve bundle in the center of the cerebrum, called the corpus callosum.


• Amygdala: This small structure in the brain has a lot of responsibility, as it’s the amygdala that is most responsible for both recognizing danger in the environment and triggering the proper fear response to deal with that danger. It regulates emotions and aggression, interprets body language and threats, affects unconscious memory, and assists in learning.


• Thalamus Like a massive relay station in the brain, all sensory input (except for smell) passes through the thalamus, as do all motor function signals. It also assists in memory, focus, and staying alert. You have two thalami, located side-by-side, above your brainstem.


• Hypothalamus Like a watchful manager, the hypothalamus maintains homeostasis by monitoring the body’s overall status and regulates body temperature, blood pressure, mood, libido, and the appetites (hunger, thirst, sleep), by interpreting nerve signals from throughout the body.


• Hippocampus The saying should be, “a hippo never forgets,” because the hippocampus is all about memory. This is where memories are stored and made, as short-term memories are formed and then turned into long-term memories within the hippocampus. It also assists in spatial navigation and perception. You have two hippocampi, one on each side of the brain.

The Brainstem

The brainstem connects the cerebrum with the spinal cord and contains the structures responsible for most of the automatic functions that, on a basic level, keep the body alive. The brainstem includes the midbrain, the pons and the medulla.

• Midbrain: This dense structure of neuron clusters and neural pathways contributes to movement, coordination, and hearing, as well as the ability to combine all of this input and respond to changes in the world around you—including threat recognition. The midbrain is also the location of the substantia nigra, high in dopamine and an area affected by Parkinson’s disease, and part of the basal ganglia, which is crucial for movement and coordination.


• Pons: This bridge between the midbrain and the medulla houses four of your 12 cranial nerves, including those responsible for blinking, balance, hearing, facial expression, and even focusing your eyes.


• Medulla Located at the bottom of the brainstem, where the brain meets the spinal cord, the medulla regulates necessary functions like breathing, blood circulation, and your heartbeat, as well as complex reflex actions like swallowing, vomiting, coughing and sneezing.

The Cerebellum

Located above the brainstem at the back of the head, the cerebellum is necessary for balance and equilibrium and plays an important role in voluntary muscle movement. Experts believe it has many more functions, however, and are still studying its possible role in emotion, thought, and addiction.

Much like the cerebral cortex, the cerebellum is also made of two hemispheres.

What About the Glands? The Pituitary and Pineal

The brain is also home to crucial structures that are not technically part of the cerebrum, cerebellum or brainstem, but are considered part of the brain, nonetheless. These include the pituitary and pineal.

• Pituitary Gland: Only the size of a pea and located behind the nose, the pituitary gland is the one gland to rule them all, regulating hormones from the thyroid, adrenal glands, and sexual glands, such as the ovaries and testicles, and generally controlling all glands in the body.


• Pineal Gland: Bad night’s sleep? Blame it on the pineal gland, which governs your sleep cycle by responding to environmental light cycles (natural and unnatural) and secreting melatonin.

Maintain Your Brain

But if the brain is busy looking out for the rest of the body, who’s looking out for the brain?

That’s why Sarasota Memorial has expert teams like the SMH First Physicians Group Neurology and FPG Neurosurgery and Spine Specialists, who bring more than 30 years of experience to the treatment of cerebrovascular diseases, brain conditions and tumors, stroke, complex spine disorders, peripheral nerve conditions, Parkinson’s disease, epilepsy, and more.

If someone you know is experiencing memory problems, confusion, unexplained mood swings, chronic and consistent headaches, movement disorders, dizziness, or any other symptoms that are cause for concern, reach out to your healthcare provider or call us at (941) 917-7777.

If neurological symptoms are severe, including trouble breathing, loss of consciousness, or a sudden onset of stroke symptoms, which can include loss of balance, blurred or lost vision, facial drooping, arm weakness, and slurred speech, call 9-1-1 immediately.

Written by Sarasota Memorial copywriter Philip Lederer, MA, who crafts a variety of external communications for the healthcare system. SMH’s in-house wordsmith, Lederer earned his Master’s degree in Public Administration and Political Philosophy from Morehead State University, KY, and uses more than 10% of his brain.