Originally, I thought "cross my fingers' would mean something like this picture shows:
But by a search for the phrase "cross my fingers images" on the web, I get most of pictures like this:
So, I want to know:
Is there a reason (if there is) why "cross my fingers' means just "cross middle finger over index finger"?
Is there a phrase to describe all the five figures of both hands get crossed just like the first picture shows?