How Does a Punch to the Jaw Cause a Knockout?
Jaw Impact
A punch to the jaw causes the head to suddenly spin around. This can be to the left, to the right, or to the back. This quick motion of the skull causes trauma to the brain that leads to a knockout. Points on the jaw that are especially vulnerable to knockouts are the sides of the chin, and where the jaw is attached to the rest of the skull.
Acceleration and Deceleration
When the jaw is punched, the head quickly accelerates around. After a fraction of a second, it quickly decelerates as muscles, tendons, and bones prevent the head from spinning any further. The brain inside the skull is floating in fluid. It accelerates slower than the rest of the head. This forces it to crash into the inside of the skull when the head stops.
Brain Trauma
When the brain slams into the inside of the skull, it suffers trauma. It then bounces off the inside of the skull and slams into the opposite side. This causes even more trauma. Depending on the force of the punch, this can happen several times before the brain comes to rest inside the skull.
Nervous System Response
The trauma to the brain stimulates an overwhelming number of neurotransmitters to fire at the same time. This essentially overloads the nervous system sending it into a state of temporary paralysis. The person who is hit in the jaw loses consciousness and their muscles relax. They fall to the ground with no memory of being hit.
Recovery
A person who is knocked out by a punch to the jaw suffers a severe concussion. It can take anywhere from several seconds to several minutes to regain consciousness. It all depends on the severity of the brain trauma. In mild cases, the person who is knocked out can shake off the punch with little more than a headache. In severe cases, brain trauma from a knockout punch to the jaw can cause cerebral bleeding and death. It is possible for someone to never wake up from a knockout punch.
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Right jab, left hook, right jab, and then ... bam! Knockout.
There is nothing more exhilarating for a boxing audience than to see a fighter hit the mat in a knockout. But being on the losing end of a KO punch can damage a lot more than a pugilist's pride—research suggests that the blows that cause knockouts can be debilitating to a boxer's short and long-term health. Repeated blows to the brain can cause chronic damage such as personality changes and dementia. If the punches have enough impact to cause uncontrollable brain swelling or hemorrhage, the fighter could even die.
So what causes a knockout? Concussions, and lots of them. While it often seems as though the effect is caused by a single well-placed shot, it is usually the result of many quick punches. Each punch creates a concussion (technically defined as any head injury that causes a disruption of neurological function), and each concussion brings the boxer closer to a state of darkness.
Here's how it happens: The body contains dissolved sodium, potassium and calcium, collectively known as electrolytes, which are responsible for conducting impulses along neurons. Every time a fighter receives a blow to a nerve, potassium leaves the cell and calcium rushes in, destabilizing the electrolyte balance, while the brain does all it can to keep these levels in balance. With each successive blow, this balance becomes harder and harder to maintain, and more and more energy must be spent in the process. When the body reaches the point where the damage outweighs the body's ability to repair itself, the brain shuts down to conserve enough energy to fix the injured neurons at a later point.
"After a brain injury, the heart must supply sufficient blood flow for the brain to repair itself. If the demand outweighs the supply the brain then shuts down and leads to an eventual loss of consciousness," says Anthony Alessi, M.D., a neurologist and ringside physician for the Connecticut State Boxing Commission. "That's when I know to end the match, because if we keep going the fighter is going to die."