Meninges: Dura Mater, Arachnoid Mater, and Pia Mater: Brain Anatomy: Meninges
Trepanning (a hole drilled or scraped into the human skull, exposing the dura mater.) for people who had headaches - probably a migraine sufferer. As A migraine sufferer, i understand completely.
The lymph vessels probably escaped detection because they’re inside a thick membrane, the dura mater, which is the consistency of leather.