**2. Surgical anatomy**

The nasal septum is a vertical midline structure that extends anteriorly to the columella, posteriorly to the sphenoidal rostrum, superiorly to the anterior skull base, and inferiorly to the nasal floor (**Figure 1**). It composed of soft tissue, cartilage, and bone. The most caudal part between the columella and the caudal margin of the septal cartilage is the membranous septum, lying between the medial crura and the caudal septum. The area of the membranous septum may vary between individuals. In people with a large septal cartilage, the membranous septum might be smaller. The cartilaginous part of the nasal septum is quadrangular. It is in conjunction with the upper lateral cartilage and the lower end of the nasal bone anterosuperiorly, the perpendicular plate of the ethmoid bone superiorly, the vomer

**Figure 1.**

*The anatomy of the nasal septum.*

bone posteroinferiorly, and the maxillary crest inferiorly. It usually presents with a tail between the gap of the perpendicular plate and the vomer, and this area is actually considered to be the growth center of the septum. The cartilaginous septum connects to the bony septum by a dense fibrous tissue and usually sits in a groove in the maxillary crest. The bony part of the septum includes the vertical crest of the nasal bone, the perpendicular plate of the ethmoid bone, the vomer, the maxillary crest, and the palatine crest. Because the septum at the bony-cartilaginous junction is the growth center of the nasal septum, we should keep in mind not to manipulate vigorously in this area before 17 and 18 years of age.

Some important landmarks of the nasal septum should be kept in mind when performing septoplasty to avoid unfavorable complications. The keystone area is the confluence of bone and cartilage at the junction of the nasal bone, the septal cartilage, and the upper lateral cartilages. The detachment of the cartilage from the bone and/or damage of the cartilage in the keystone area may cause a complication known as a saddle nose. Another important landmark is the junction of the caudal septum and the anterior part of the maxillary crest. There are three landmarks in the caudal ends of the septal cartilage: the anterior septal angle, middle septal angle, and posterior septal angle. The posterior septal angle contacts the anterior nasal spine, which is the most anterior part of the maxillary crest. Damage to the fibrous connection between the caudal septum and the anterior nasal spine may lead to weakened support of the nasal tip and an increased risk of nasal tip drooping. Usually, the septal cartilage should be preserved at least one 1–1.5 cm in width dorsally and caudally.

Deviation of the nasal septum can be classified as a caudal septal deviation, dislocation of the cartilage out of the maxillary crest, dorsal and high septal deviation, posterior septal deviation, and a bony spur formation. Various techniques have been proposed to deal with the distinct sites of septal deviation.
