The Human Brain

The Human Brain

on Posted in About brain injury.


Photo © Dr Ahmad Haneih MBBCH,FRCS,FRACS

Dimensions and Sizes

Average dimensions of the adult brain:

Width = 140 mm/5.5 in, Length = 167mm/6.5 in, Height = 93 mm/3.6 in.

How much does human brain weigh?

At birth our brains weigh and average of 350-400g (about 4/5 lbs), as adults the brain averages 1300-1400g (about 3 lbs).
If stretched out the cerebral cortex would be 0.23 sq. m(2.5sq.ft), the area of a night table.
Total surface area of the cerebral cortex is 2,500 cm2 or 2.69 sq.ft.


The composition of the brain = 77-78% water, 10-12% lipids, 8% protein, 1% carbs, 2% soluble organics, 1% inorganic salt.

The breakdown of intracranial contents by volume (1,700 ml, 100%): brain = 1,400 ml (80%); blood = 150 ml (10%); cerebrospinal fluid = 150 ml (10%).

The cerebellum contains half of all the neurons in the brain but comprises only 10% of the brain.
The cerebral cortex is about 85% of the brain.
Percentage of total cerebral cortex volume = frontal lobe 41%, temporal lobe 22%, parietal lobe 19%, occipital lobe 18%.

There are about 100 billion neurons in the human brain, the same number of stars in our galaxy.
The left hemisphere of the brain has 186 million more neurons than the right hemisphere.
750-1000ml of blood flow through the brain every minute or about 3 full soda cans.

In that minute the brain will consume 46cm3 (1/5 cups) of oxygen from that blood.
Of that oxygen consumed, 6% will be used by the brain's white matter and 94% by the grey matter.

The brain can stay alive for 4 to 6 minutes without oxygen. After that cells begin die.The slowest speed at which information travels between neurons is 416 km/h or 260 mph, thats as "slow" as todays supercar's top speed (the Bugatti EB 16.4 Veyron clocked at 253 mph).10 seconds is the amount of time until unconsciousness after the loss of blood supply to the brain.Time until reflex loss after loss of blood supply to the brain, 40-110 seconds.During early pregnancy the rate of neuron growth is 250,000 neurons a minute.

Other Fun Facts About The Human Brain

Results from cognitive tests show 30% of 80-year-olds perform as well as young adults.
Your brain is about 2% of your total body weight but uses 20% of your body's energy.
The energy used by the brain is enough to light a 25 watt bulb.
More electrical impulses are generated in one day by a single human brain than by all the telephones in the world.

How much does human brain think?

70,000 is the number of thoughts that it is estimated the human brain produces on an average day.
After age 30, the brain shrinks a quarter of a percent (0.25%) in mass each year.
Albert Einsteins brain weighed 1,230 grams (2.71 lbs), significantly less then the human average of 1,300g to 1,400g (3 lbs).
Each year Americans consume 50 billion aspirin tablets or 15.5 million tons.
89.06 is the percentage of people who report normally writing with their right hand, 10.6% with their left and 0.34% with either hand.

Source Brain Health