What is the interaction between the lithosphere and asthenosphere

Here are a couple of links. Remember there is always Google and Wikipedia to help you.

Earth's Crust, Lithosphere and Asthenosphere (http://www.windows.ucar.edu/tour/link=/earth/interior/earths_crust.html&edu=high)
Lithosphere - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Lithosphere)
Asthenosphere - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Asthenosphere)