These are called sail panels.Some headliner are all one piece and others use sail panels in the area you are talking about. Jim
The liner fold over the teeth and then the sail panel laps over the headliner abit.The sail panels go behind over and behind the teeth they are shaped like a sail or triangled.Then there are metal pieces that go around the sides and top.Then at the bottom of the glass on top of your speakerpackage tray there is a plastic piece that goes along there.
Jim