The topography of the region is highlighted by the shadows and curvatures that make this area a visual landmark. These relationships are critical to the appearance of the alar base: the curved insertion of the ala into the face, the shadows of the alar-facial groove and the alar crease, the convex reflection of the ala, and the smooth
transitions between the ala, nasal tip, and nasal sidewall. These subtle intricacies make modification of the alar base a surgery of millimeters (Fig. 21.1).

The alar base occupies the caudal third of the nose. The boundaries of the alar base include (1) the alar crease, which separates the ala from the nasal sidewall superiorly; (2) the alar-facial groove, which separates it from the cheek and apical triangle of the upper lip laterally; and (3) the crease across the nasal sills and subnasale, which divides the upper lip from the nose and delineates the inferior border of the alar base.

The external structure of the alar base is comprised primarily of the ala and alar lobule, which is comprised of skin, muscle, and fibroadipose tissue. There is no cartilage in this region, and the soft tissue support arises from the tight attachments of the skin to underlying fibroadipose ligaments. The columella is the skin and soft tissue overlying the paired medial crura of the lower lateral cartilages. This structure commonly makes a smooth transition from the infratip and soft triangle regions, over the medial crural footplates, and then curves laterally to join the nasal sills. Internally, the nasal vestibule is bounded by the membranous septum medially, the medial aspect of the ala laterally, and the nasal sill inferiorly. The nasal sill is the soft tissue area between the medial crural footplate and the alar-facial groove. Functionally, the external nasal valve is framed by the ala, the membranous septum, and the nasal sill/nostril floor.

Physical examination of the alar base requires a structured approach. The following five components should be evaluated (see Table 21.1):

The ideal Caucasian alar base width, measured as the transverse distance between the two insertions of the alae into the face, is typically equal to or slightly more than the intercanthal distance (Fig. 21.2). Alternatively, desirable alar base width can be measured as approximately 70% of the nasal length, defined by the distance from the nasal tip to the nasion. This value is variable, dependent on ethnicity as well as patient and surgeon preferences. For example, in African American men, the ratio of inter-alar to intercanthal distance is approximately 1.3:1, whereas the female ratio is 1.25:1. In southern Chinese women, it is also more common to have a nasal width greater than the intercanthal distance in addition to the alae having increased flare and the nostrils having a greater horizontal orientation. At the facial insertion point, the alar base should typically assume a medially directed curvature, rather than a straight insertion. The position of insertion of the ala into the face can dramatically impact esthetics, producing excessive columellar exposure or a snarl-like appearance.

In Caucasians, the nostrils should be pear shaped, approximately equal in width to the columella, and their long axis should be oriented at a 30 to 45 degrees angle to the vertical axis of the columella. Farkas and colleagues have developed an objective assessment system for different nostril types.

The nostril sill region may be normally notched or smooth, depending on its transition with the alar-facial groove. In some patients, the sill is flat, while in others, it is a slightly elevated roll of skin. Regardless, it is commonly recognized as the anterior base of the nasal aperture (nostril) and is commonly, but often overlooked, nasal landmark.

The columella width is largely a function of the medial crurae and should appear symmetric without significant medial crural footplate flare. The Caucasian nasal base is ideally shaped like an equilateral triangle, with a 2:1 ratio of columellar height to tip lobule height.

On frontal view, the alar margins should take on the appearance of a “gull in flight.” On lateral view, the alar contour should describe a gentle curve. Crumley noted an ideal 1:2:3 relationship between the length of the alar base, the nasal tip lobule, and the length of the nostril in the profile view. On base view, the alar lobule width should be less than one-fifth of the total transverse width of the nasal base. Alar flare is best appreciated on base view and is defined as the portion of the ala extending laterally past the alar-facial insertion point. Silver has suggested that lateral excursion of the alar rim greater than 2 mm beyond the alar-facial insertion point should be considered significant.

The alar-columellar relationship is best described by drawing a meridian line between the anterior and posterior terminal points of the nostril. If the alar rim is greater than 2 mm above this line, there is alar retraction. If the alar rim is less than 1 mm above this line, then alar “hooding” is present. Alar hooding can be due to excessive alar bulk or from a distal caudal insertion point of the ala, thereby obscuring the columella on lateral view. If the columella is greater than 2 mm below this line, there is a hanging columella. If the columella is less than 1 mm below this line, the columella is considered retracted (Fig. 21.3).