Expandable Image Help!

[Verrou]

I have an image:

I want to know how to make it so that the pic expands with the text, and i just want the middle to expand to so the bottom is kept the same...get what i mean?

Because when it expands it should drag the bottom down and if it does it will make the bottom of the pic go all funny. So i want the middle to expand and the bottom not to

[Heinous]

img
div (with the middle as a background image for the div)
img