TK,
Liz had a lot of good information for you. I too had signifcant mandibular involvement, however surgery was performed in my case since the tumor had not migrated into facial soft tissue structures too extensively.

the tempormandibular joint is the hinge joint on either sides of the jaw. Trismus refers to the inability to open ones mouth. that's a very common thing for many oral cancer patients.

To restate what others have said..keep coming back here. There is a vast amount of first hand experience to draw strength from. You're both in for a tough journey, but it is not hopeless. Statistics will drive you crazy and really don't mean anything to you individually. concentrate your efforts on getting treatment underway as quickly as you possibly can, and get ready for a fight; you've got one on your hands
Wayne