We’ve all heard about hair and fingernails continuing to grow after death (or they actually don’t, it’s really the skin retracting or whatever). But could you crack a dead person’s knuckles after death?
If so, for how long? If you could do it once, could you do it again? There’s a sort of refractory period after cracking a knuckle - how many cycles could you get out of a freshly dead body?
Well, the cracking sound is produced by gas bubbles and stretching some tissue. Once you’re dead, I would think the gas bubbles would shut down and the tissue stretch would also stop at some point.
How long after death? 5 minutes? Probably. 2 days? Doubt it.
Rigor mortis starts to set in somewhere between 2-6 hours after death. I don’t think the knuckles will be too easy to crack after that.
But rigor mortis ceases 48 to 40 hours after it begins, due to decay of the myofilaments ( Rigor mortis - Wikipedia )
I suppose that the loss of elasticity I the synovia , or their leaking, or some such change will prevent the cavitation that allows bubbles to form in the synovial fluid, causing the cracking. But I don’t know enough about the processes of decay to say.
It’d be interesting if loss of the ability to crack knuckles turned out to be one of the signs of vampirism.
“It’s strange, Dr. Van Helsing, but when we were all standing around cracking our knuckles, the Count said it was a silly activity and refused to take part.”
“Interesting. Tell me, was there a mirror nearby?”