I don't remember anything else about the movie, but that scene stuck in my mind.
I think this was Dracula, Prince of Darkness
Have a look at the trailer here:
Or view the full movie here:
Per @user32992's stub of an answer, could you be referring to the classic 1944 thriller "House of Frankenstein"? Early in the film we see a stake being removed from Dracula's skeleton. His body then reforms (complete with circulatory system and muscles) as we watch.
Please note the original effect was much better. I've heavily edited the clip for brevity.