Lateral process of nasal septal cartilage

The lateral process of the nasal septal cartilage (also referred to as the dorsal lateral extension of the quadrangular cartilage) is the portion of the septal cartilage that extends laterally from the dorsal border of the nasal septum. In classical anatomical descriptions, the septal cartilage and the upper lateral cartilages are often considered a single continuous cartilaginous structure sometimes called the "T-shaped" cartilage in which the lateral processes represent the paired lateral wings that splay outward from the dorsal septum to form the middle third of the nasal dorsum and the medial boundary of the internal nasal valve.

Anatomical relationships and features:

• The upper lateral cartilage is described as a triangular cartilage that meets the nasal bones superiorly, the lower lateral cartilages inferiorly, and fuses with the septum in the midline. This midline fusion zone is the lateral process of the septal cartilage.

• Microscopic examination of cadaveric specimens has demonstrated extreme variation in the attachment between the septum and the lateral nasal cartilage, ranging from no cartilaginous connection to complete fusion. The mean length of the connection between the upper lateral cartilage and the septal cartilage has been measured at approximately 16.1 mm, with separation from the septal cartilage beginning on average 7.5 mm from the nasal bone.

• The upper lateral cartilage averages approximately 22.5 mm in length and 13.7 mm in width, and underlaps the nasal bone by about 15 mm from the nasal septum laterally.

Functional significance:

The lateral process is critical for maintaining the structural integrity of the nasal dorsum and the patency of the internal nasal valve, which is the area bordered by the upper lateral cartilage laterally, the septum medially, the head of the inferior turbinate, and the floor of the nose. Disruption of this junction during rhinoplasty (e.g., during dorsal hump reduction) can lead to internal nasal valve collapse and nasal obstruction. The septal cartilage is thickest along its base (~2.7 mm) and dorsum (~2.0 mm), and thinnest centrally (~1.3 mm) and at the anterior septal angle (~1.2 mm), which has implications for structural stability when the lateral process is surgically altered.