The most reliable midline marker is the pterygoid sinus opening, as the septum is often severely deviated or curved from the midline, but the pterygoid sinus opening is always stable in the middle. However, the relationship with the pterygoid sinus is not always stable and sometimes varies. In fact, the more reliable markers are the middle turbinate and posterior nasal aperture, and no anatomical variation has been found in determining the anterior-posterior position. The posterior nasal aperture and nasopharynx can be seen along the inferior border of the middle turbinate. But pay attention to the nasal dike (located anterior to the anterior part of the middle turbinate, on the lateral wall of the nasal cavity above the anterior part of the hooked process, in the form of a small mound-like elevation containing one to three airspaces, called the nasal mound airspaces, formed by pneumatization of the tear bone by the frontal crypt airspaces, representing the most anterior part of the anterior group of septal sinuses.) Sometimes the pneumatization is too good, don’t take it as nasal turbinates. Xin Lin, Department of Neurosurgery, Tianjin Huanhu Hospital, Tianjin, China Figure.