22 Common Misconceptions You've Always Believed (Until Now)
18. Cracking Your Knuckles Causes Arthritis
At face value it appears perfectly reasonable to assume cracking your knuckles increases your chance for arthritis. But knuckle cracking doesn't actually crack anything; its just bubbles bursting in the synovial fluid in the joints. There is no connection between cracking your knuckles and arthritis.
17. Hair & Fingernails Keep Growing After Death
It may look like the hair and fingernails continue to grow after a person dies, but this is actually the result of shrinking skin via dehydration. New cells need to be produced in order for hair and nails to keep growing, and this is impossible after death.