Join Date: May 2009
Location: Imperial, CA
Rep Power: 6
Total Points: 70,713,616.28
Cuts around eyes can scar, leaving less tissue than what was originally there, so cuts can re-occur easier the 2nd third, or later on.
The same holds true for a face that puffs up easier after having been beaten on. These are somewhat permanent results from taking punishment.
However, the notion of "cracking" a chin is more a figure of speech than anything else. I know I'm sounding nit-picky here, but let's seperate fact from fiction.
Can a chin be cracked from a punch? I guess it could, but that would make for some pain, rather than knockout or 10 seconds of sleep.
I don't understand a "Glass Chin" as being something you acquire, but rather something that you already have.
The science behind the knockout involves the membrane between the skull and brain. When a person has more membrane, they are more difficult to knock out. There is more cushioning for the brain to avoid bumping the skull druing a violent punch. It's that bumping that shuts part of the brain down (defense mechanism) and puts someone to sleep. So, it would bear to note that if someone has less membrane (cushioning), they are naturally more inclined to be knocked out when getting hit. Conversely, another person with more membrane, who gets hit with the same exact punch, would be more inclined to accept the punch without being knocked out. Again, because the brain has more cushioning and doesn't bump the skull.
You can't diminish this membrane...it exists in excess or it doesn't. So either you are born with a glass jaw (propensity to be knocked out) or you are not.
The reason a boxer tends to get knocked out more after a vicious knockout is more due to the psychological scar he acquires from the knockout than anything else.
Once placed in trouble again, a boxer may overcompensate protecting his chin that he leaves himself open more, thus leaving more opportunity for that shot to land and ko him again.