Teeth of Sithis delve map in Murkmire including the location of boss and skyshard. Quest giver is right outside the “cave” entrance to the delve.
Follow the arrows on our map for easy Teeth of Sithis completion. First go through the door to Level 2, then complete quest objectives there and exit to Upper Level 1. Talk to indicated NPC, cross the bridge and pick up the skyshard, then use the upper platform door to go back to Level 2. Delve boss is at the very end of the delve, and exit back to Murkmire is right past her.