The human nose serves both a functional and aesthetic role. The alar is a specific component central to the form and function of the lower third of the nose. Understanding its anatomy, mechanical purpose in breathing, and relationship to facial proportions provides a complete picture of this often-overlooked part of the face.
Defining the Alar: Location and Structure
The alar, or ala, refers to the lateral, wing-like, fleshy part of the nose that forms the outer curve of the nostril. It extends from the tip of the nose to where the nose meets the cheek. The alar forms the sidewall of the nasal vestibule, the entrance to the nasal cavity.
This structure is complex, consisting of multiple layers. Underlying support comes primarily from the lateral crus, the outer portion of the lower lateral cartilage. Since the cartilage does not fully extend to the cheek, the space is filled by fibrofatty tissue. This combination provides the nostril rim with its pliable yet defined shape.
The Role of the Alar in Nasal Function
The alar regulates airflow dynamics within the nose. The alar rim and surrounding tissues form the external nasal valve, the narrowest point of the airway at the nostril entrance. The size and shape of this opening determine how easily air passes into the nasal passages.
The structural integrity provided by the lower lateral cartilage is necessary to prevent external nasal valve collapse. During deep or vigorous inhalation, the negative pressure created inside the nose can cause the flexible alar rim to collapse inward. The strength and positioning of the alar cartilages must be sufficient to resist this inward suction, ensuring a stable airway for optimal breathing, especially during exercise.
Alar Dimensions and Aesthetic Considerations
The dimensions of the alar base, the widest part of the nose where the alae meet the cheeks, are a significant factor in facial harmony. Aesthetic ideals suggest that the width of the alar base should align with the distance between the inner corners of the eyes, a measurement known as the intercanthal distance. An alar base significantly wider than this measurement is often described as having excessive flare.
When the alae appear too wide or the nostrils too flared, the nose can look disproportionately large. To address this aesthetic concern, a surgical procedure called alarplasty, or alar base reduction, is often performed. This involves the precise removal of a small wedge of tissue from the alar base to narrow the overall width of the nostrils and refine the nasal contour.