What is external nasal anatomy?

Updated: Jul 13, 2021
  • Author: Samuel J Lin, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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External nasal anatomy can best be considered in structural thirds. The upper third includes the paired nasal bones. The middle third is composed of the stiff paired upper lateral cartilages fused to the septal cartilage in the midline. The lower third of the nose consists of softer lower lateral cartilages. From a functional standpoint, the lower and middle thirds of the nose play an important role in the nasal valve. The external nasal valve is defined laterally by the nasal ala and medially by the septum, whereas the internal valve is defined by the attachment of the upper lateral cartilage to the septum, which forms an angle of approximately 15°. [1] The anterior face of the inferior turbinate defines the lower boundary of the internal nasal valve. The entrance of the nasal cavity consists of the piriform aperture, which is defined as the frontal process of the maxillary bone, floor of the nose, and lateral fibrofatty tissue.

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