Points of Light
On the keystone of the dark archway above this path is a chiseled horizontal line with a vertical line beneath it. The passage beyond leads to another of the myriad branches of the Road of Shadows. This particular branch connects the Seven Pillared Hall with the excavation site of the Palace of Zaamdul.
You have discovered in your adventures within Thunderspire, the glyph chiseled above the archway is a reference to Torog, the King that Crawls.