auto appending for each directory

I'm developing a web page with a directory structure like this: /main -----/subject1/ --------------/subsubsect11 --------------/subsubsect12 --------------/subsubsect13 --------------/subsubsect14 --------------/subsubsect15 -----/subject2/ --------------/subsubsect21 --------------/subsubsect22 --------------/subsubsect23 --------------/subsubsect24 --------------/subsubsect25 -----/subject3/ etc..... What I would like to do is have a menu for each directory which is saved in a seperate file, (so there is a menu for main, menu for subject1, menu for subsubject11, etc). I need a php script that finds out what directory a current web page is in and automatically append all the menu files for each directory up to the current directory. I know that php has functions for both directory access and file access. Could somebody give an idea how I can achieve this with php. many Thanks Rishabh