What is middle ground in art painting?

THE MIDDLE GROUNF IS THE SAME AS BACKGROUN EXCEPT IT IS A LITTLE CLOSSER TO THE FORGROUND eg...IN The Mona Lisa THE RIVER AND THE GROUND IS THE MIDDLE GROUND AND THE MOUNTAINS ARE THE BACKGROUND AND MONA LIS WITH A LIGHT GRIN IS OBVIOUSLY THE FOREGROND

THATS THE FOREGROND MIDDLE GROUND AND BACKGROUND FOR YOUU

I HOPE THIS ANSWERE YOUR QUESTION

I AM IN YR 12 AND I DO ART I REMEMBER STUDDING MONA LISA IN YR 9