This is the forum for helping you out if you're stuck or if you want to discuss the nitty gritty details of the dungeons within Mount Grimrock. Warning: forum contains spoilers!
I appreciate the reply, but I did find the key already. I was more concerned that the three or so rooms that you fall into from 10 weren't the limit of your interaction with 11.
I've since answered this myself, so I may as well clue you in. There is more to it but you return to this level from ones lower down. Don't stress yourself about it the first tyime you get there.