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50 free The Human Brain trivia questions with answers — science & nature quiz, new questions added Aug 2026.
The human brain weighs about as much as a bag of sugar, has the consistency of soft tofu, burns a fifth of the body's energy and floats in fluid so that 1,400 grams of tissue effectively weighs less than 50. It holds around 86 billion neurons, most of them packed into the little cerebellum at the back, and it has taught scientists most of what they know through accidents and operations: a railroad foreman with an iron rod through his skull, an epileptic patient who could never form a new memory again, and a dye that stained every organ except one. These 50 questions cover the anatomy and the stories: the cerebrum, brainstem and cerebellum, the four lobes and the skull bones they are named for, the corpus callosum's 200 million fibres, the six layers of the neocortex and Brodmann's fifty areas, the hippocampus, amygdala, hypothalamus and pineal gland, the three meninges and four ventricles, the carotid and vertebral arteries, Broca's area and left-brain language, glia and myelin, action potentials and synapses, Ramón y Cajal, Sherrington and Hans Berger's first EEG, Phineas Gage, H.M., Egas Moniz's lobotomy, phrenology, Neanderthal brain size, the sperm whale's 8-kilogram brain, concussion and neuroplasticity. Easy questions stick to lobes and neuron counts; the hardest ask about oligodendrocytes, alpha-wave frequencies and the default mode network. Every answer is cited to a page we checked, with a short explanation so you learn something even when you miss. Play it solo or print it for a biology class or a pub science round.
30 of 50 questions with answers and explanations. Play the quiz
Q 01Roughly how many neurons does the human brain contain?
86 billion
There are about as many non-neuronal cells again, mostly glia; the cerebellum alone holds most of the neurons.
Q 02About what share of the body's energy does the brain consume?
20%
That is more than any other organ, from roughly 2% of body weight; it also takes about a quarter of the body's glucose.
Q 03The adult human brain weighs on average about how much?
1.2–1.4 kg
Men's brains average about 1370 g and women's about 1200 g, with wide individual variation.
Q 04What everyday food is the living brain's consistency compared to?
Soft tofu
That softness is why the brain floats in cerebrospinal fluid inside the skull rather than resting on bone.
Q 05Which three main parts make up the human brain?
Cerebrum, brainstem and cerebellum
The cerebrum is by far the largest; the brainstem links it to the spinal cord and the cerebellum sits behind.
Q 06The four lobes of each hemisphere are named after what?
The skull bones above them
Frontal, parietal, temporal and occipital all share names with the bones of the skull above them.
Q 07Which lobe of the brain is dedicated to vision?
Occipital
It sits at the back of the head and holds most of the visual cortex; the frontal lobe handles planning and self-control.
Q 08Which is the largest lobe of the vertebrate brain?
The one at the front
The frontal lobe is also the most forward lobe, and the one Phineas Gage's tamping iron passed through in 1848.
Q 09What is the name of the largest bundle of fibres connecting the two hemispheres?
Corpus callosum
It is the brain's largest white-matter structure, about 10 cm long with 200–300 million axons.
Q 10Roughly how many axonal projections run through the main bridge between the hemispheres?
200–300 million
It is about 10 centimetres long; severing it was once used to treat severe epilepsy.
Q 11How thick is the cerebral cortex, the brain's folded outer layer of grey matter?
2 to 4 mm
Its deep folds pack far more surface area into the skull; the neocortex has six layers of neurons.
Q 12How many neuronal layers does the neocortex have?
Six
The older allocortex, which includes the hippocampus, makes do with three or four.
Q 13The cortex is mapped into about fifty functional regions named after which anatomist?
Brodmann
Korbinian Brodmann's areas look distinctly different under the microscope; Area 17 is the primary visual cortex.
About what fraction of total brain volume is white matter?
Q 21Which almond-shaped structure in the temporal lobe is central to processing fear?
Amygdala
Its name comes from the Greek for almond; there is one in each hemisphere.
Q 22Which structure links the nervous system to the endocrine system via the pituitary gland?
The hypothalamus
About the size of an almond, it also regulates body temperature, hunger, thirst, sleep and circadian rhythms.
Q 23Which small organ produces melatonin and was called 'the principal seat of the soul' by Descartes?
The pineal gland
Melatonin is derived from serotonin and tracks the day–night cycle; the gland is named for its pine-cone shape.
A half
White matter is mostly myelinated axons, the insulated wiring beneath the grey-matter cortex.
Q 15What does the brainstem consist of?
The midbrain, the pons and the medulla oblongata
The medulla holds the centres for heart rate, breathing and blood pressure.
Q 16Which part of the brainstem contains the centres controlling heart rate, breathing and blood pressure?
The medulla
It is the lowest part of the brainstem, continuous with the spinal cord.
Q 17The name of the structure behind the brainstem means what in Latin?
Little brain
The cerebellum occupies about 10% of brain volume yet contains more neurons than the rest of the brain combined.
Q 18Which brain region holds more neurons than all the rest of the brain combined, in only 10% of its volume?
The cerebellum
Its tiny granule cells account for the numbers; damage produces problems with balance, posture and fine movement.
Q 19Which structure is named from the Greek for 'seahorse' because of its curved shape?
Hippocampus
Venetian anatomist Julius Caesar Aranzi first likened it to a silkworm in 1587 before settling on the seahorse.
Q 20Which structure consolidates short-term memories into long-term ones and supports spatial navigation?
The hippocampus
It is one of the first regions damaged in Alzheimer's disease, which is why memory loss is an early symptom.
Q 24What are the three membranes covering the brain and spinal cord collectively called?
Meninges
From the outside in they are the tough dura mater, the arachnoid mater and the delicate pia mater.
Q 25Which of the three membranes around the brain is the tough outermost layer?
Dura mater
Cerebrospinal fluid sits in the subarachnoid space between the arachnoid and the pia.
Q 26How many interconnected ventricles produce and circulate cerebrospinal fluid inside the brain?
Four
About 500 ml of fluid is made each day, though only around 125 ml is present at any one time.
Q 27Suspended in cerebrospinal fluid, a 1,400-gram brain has an effective weight of about how much?
25–50 grams
That buoyancy is what stops the soft brain from crushing itself against the skull.
Q 28Paul Ehrlich's injected dyes famously stained every organ in his test animals except which one?
The brain
Ehrlich was studying staining for microscopy; the barrier is a selective layer of endothelial cells.
Q 29The blood–brain barrier remains permeable to which of these?
Alcohol
It passes water, oxygen, carbon dioxide and most fat-soluble substances, which is why anaesthetics work.
Q 30Which vessels supply blood to the front of the brain?
The internal carotids
The vertebral arteries feed the back; a loss of blood supply is a stroke.