What are the boundaries of the nasal septum?

Anatomical Boundaries of the Nasal Septum

The nasal septum is an osteocartilaginous wall dividing the nasal cavity into two chambers, with specific bony and cartilaginous components forming its superior, inferior, anterior, and posterior boundaries. 1

Structural Components and Their Boundaries

The nasal septum consists of four primary anatomical components that define its boundaries 2:

Superior Boundary

• Perpendicular plate of the ethmoid bone forms the superior-posterior portion, comprising approximately 43% of the total septal area 2
• This bony component extends from the cribriform plate downward 2

Inferior Boundary

• Vomer bone forms the inferior-posterior boundary, representing approximately 25.8% of the total septal area 2
• Nasal crest of the maxilla forms the inferior-anterior floor, accounting for approximately 5.6% of the total septal area 2
• The floor of the pyriform aperture marks the most inferior extent where the septum meets the nasal floor 3

Anterior Boundary

• Septal cartilage (quadrangular cartilage) forms the anterior portion, comprising approximately 25.6% of the total septal area 2
• The caudal edge of the septal cartilage represents the most anterior boundary 4
• This cartilaginous component is critical as it forms the medial boundary of the internal nasal valve 3

Posterior Boundary

• The junction where the perpendicular plate of the ethmoid and vomer meet the sphenoid bone posteriorly 2

Clinical Relevance of Septal Anatomy

The Septal Body

• A specialized thickened area exists on the septum located 2.2 ± 0.3 cm behind the caudal edge of the septal cartilage and 1.1 ± 0.2 cm above the nasal floor 4
• This region has mean dimensions of 2.0 cm horizontally and 1.5 cm vertically 4
• The septal body sits superior to the inferior turbinate and anterior to the middle turbinate, with histologically distinct mucosa containing abundant seromucinous glands and blood sinusoids 4

Functional Significance

• The anterior cartilaginous septum forms the medial boundary of the internal nasal valve, which accounts for more than two-thirds of total nasal airflow resistance 3
• Anterior septal deviations are far more clinically significant than posterior deviations because they directly affect the valve area 3
• Approximately 80% of the population has an off-center septum, but only 26% have clinically significant deviation causing symptoms 5, 3

Common Clinical Pitfalls

• A well-developed septal body may be misdiagnosed as high septal deviation due to its thickened appearance 4
• Failing to recognize that the septum and perichondrium function as a biomechanical unit can lead to surgical complications 6
• The perichondrium is tightly attached to underlying cartilage without clearly distinguishable zones, making precise dissection critical 6