The anterior portion of the nasal cavities, from the nostril to the nasal valve (NV), is the place of highest nasal resistance to airflow, paramount to nasal physiology. There are different terminologies for the same anatomic structures in the literature.
Aim: The aim of this paper was to study the NV function and define clearly the structures of the anterior portion of the nasal cavities, mainly the region of the NV.
Conclusion: Internum ostium is the anterior segment and isthmus nasi is the posterior segment of the NV region.