Deviation 1... Much of the airflow through the nose occurs through the narrow space between the septum and the inferior turbinate A common cause of nasal airway obstruction is called a nasal septal deviation. This is a view of the nasal passage with the external nose removed. The septum can narrow this space on one side if it is deviated to that side. A ridge of bone that can often narrow the opposite side is seen. 1999 Peter Casano, M.D.