Here is what happens when your brain is shaken or stirred.
Taken from Newton’s Football:
What exactly is a concussion? Robert Cantu, co-director of Boston
University’s Center for the Study of Traumatic Encephalopathy
and one of the world’s leading experts on head injuries, describes a
concussion as “an alteration in brain function induced by biomechanical
forces.” Those biomechanical forces include sudden acceleration
and then deceleration of the head, which can cause the brain
to crash into the inside of the skull or be twisted or strained in such
a way that certain symptoms result. Those symptoms may include,
but are not limited to, headache, nausea, sensitivity to light and
noise, dizziness, amnesia, drowsiness, the inability to concentrate,
and fatigue. Some minor concussions resolve within minutes, while
in severe cases a post-concussion syndrome can last for years.
In general, the skull does a good job of protecting the brain
against the dangers that an early human might have encountered,
like a fall onto soft ground or getting hit with a small stick. Of
course, the skull—and the brain it’s protecting—fares less well
against modern dangers like bullets and motorcycle crashes. Or a
270-pound middle linebacker running at full speed and driving the
point of his helmet into your chin.
Learn more about the science behind football here: