Muhammad Ali's Broken Jaw X-Ray ... Rakes In Big Money!

In the market for an authentic X-ray of Muhammad Ali's broken jaw??? Well, too bad ... 'cause it just sold at one of the coolest charity auctions we've ever seen.

It's a pretty cool piece of memorabilia -- taken right after Ken Norton busted his face during their big fight in 1973 ... a fight Ali actually lost.

Ali signed the X-ray, "To Carol & Russ From Muhammad Ali, 1973" ... and it ended up in the private collection of "Simpsons" creator Sam Simon, a HUUUUGE boxing fan.

Simon's massive collection was auctioned off to raise money for his charity organization -- along with a TON of other cool stuff -- with the X-ray raking in a cool $1,500! No word on the I.D. of the buyer.

All of the proceeds from the auction -- which raised more than $250k -- supports both animal welfare programs and poverty alleviation and disaster relief organizations.