When the X-men movie came out and we saw Wolverine, the Claws migrated to the knuckles as shown here.
Whups. That was the wrong picture above. Three claws on the knuckle as shown below in the X-Men movies.
Quickly after the movies, comic books started having Wolverine and his claws pop from his knuckles with the special effect, SKINT!
I was looking at some comics today and notice this image of Wolverine.
I had to do a double take. Did the artist draw Wolverine's claw incorrectly or is that how he is now? So I looked for more recent images of Wolverine and his claws and found another with the same deal.