Uncinate 1... The uncinate bone is shown with slots drilled to help see the other side. The middle turbinate is partially removed. The frontal sinus and anterior ethmoid cells drain into a space just inside of the uncinate bone. This space diverts drainage back so that it will be directed down the throat for swallowing. The drainage crosses over the free edge of the uncinate bone and mixes with the drainage coming from the maxillary sinus. The final common path is over the surface of the inferior turbinate. 1999 Peter Casano, M.D.