Trephination (also known as trepanning or burr holing) is a surgical intervention where a hole is drilled, incised or scraped into the skull using simple surgical tools. In drilling into the skull and removing a piece of the bone, the dura mater is exposed without damage to the underlying blood-vessels, meninges and brain.
This is a companion discussion topic for the original content at https://www.worldhistory.org/Trephination/.