How did they get the truss rod in my axis ss?

I’m looking at my Axis SS (around 15 years old s/n G16820 ) The neck and fretboard are birds eye maple and appear to be one piece, i.e. the fretboard is part of the same maple as the neck. I can’t see a join where the fretboard attaches to the neck, and the grain pattern continues fluidly from the neck to the fretboard. Is this neck/fretboard made from one solid piece of maple? If so, how did they get the truss rod in?
Andy