A small thin bone called the uncinate bone is shown here with slots drilled into it so you can see what is on the other side. Part of the middle turbinate has also been removed. The forehead sinus and the front ethmoid cells drain into a small channel just inside the uncinate bone. This channel directs the drainage back toward the throat so it can be swallowed. The drainage spills over the free edge of the uncinate bone and mixes with the fluid coming out of the cheek sinus. From there, it flows along the surface of the lower turbinate.