Defining the flow-limiting segments in the nose (valve) was originally proposed by Mink. The arbitrary division into internal and external nasal valves is commonly referred to in the surgical literature, and a large range of surgical innovations have been proposed to rectify deficiencies reducing nasal airflow. However, defining exactly what is meant by these areas, both in a static and dynamic form and an appropriate link with clinical correlation, has led to some confusion as to which technique(s) to apply in individual functional problems. Part of the problem rests with inconsistent anatomical diagnosis in defining the clinical area of insufficiency given the considerable variations in form, shape, strength, and dynamic stability of the nose from the nostril margin to the bony pyriform aperture. For many years, nasal function was linked directly to the septum or inferior turbinates; however, the area of interest in the airway is the region in the nose covering 2 to 3 cm from the external nares controlled by hard fixed tissue structures, mucosal changes, and a variably dynamic lateral side-wall (cartilages and musculocutaneous structures) together with clearly defined ligaments. Descriptions of the lateral wall into zones have been published previously by Tsao whose article proposes/adds a more complete method of assessment.

Recent publications point out the benefit of recreating stability in the valve region as the majority of surgical procedures weaken or destroy its various elements leading to insufficiency and a reduction in function.

This chapter does not intend to comprehensively itemize the correct treatments rather I hope to provide a more reliable method of assessment and documentation based on the principle of four planes of the valve beginning at the nostril margin and considering medial and lateral contributions to the flow-limiting segment. The proposal is based on anatomic descriptions, which have clinical relevance and encompass the entire region from medial to lateral, floor to roof of the flow-limiting segment of the nose.

Deformities of the dorsum invariably reflect a displacement of the dorsal septum. Obvious sidewall asymmetry may be seen at rest particularly in the middle third of the nose. Alar pinching, abnormal curvature or position of the tip (ptosis), and caudal displacement of the cartilaginous septum are common deformities in the tip. Fixed obstructions in the nose produce a constant block. This may be reflected in the positions a patient prefers during sleep to maintain an airway, but dynamic collapse will usually be evident on increased nasal airflow.

Using this classification, with a combination of a direct, modified Cottle maneuver, endoscopic and radiologic (CBCT) investigation, deformities can be classified in the flow-limiting segment. For example, a caudal septal deformity in the left airway and a collapsed upper lateral cartilage with impingement on the septum would be area 2 medial left and area 3 right lateral. In this way, each nostril and valve can be separately categorized in a three-dimensional manner relevant to the technique required.