The vertical midline nasal septum is comprised primarily of a single nasal cartilage from the external nose and two bones. Anteriorly the septal cartilage (or quadrangular cartilage) which approximates a quadrilateral shape. Posteriorly it meets the concave anterior margins of the ethmoid and vomer. Superoposteriorly is the perpendicular plate of the ethmoid, inferoposteriorly is the vomer; these two bones have a diagonal articulation running in a superoposteriorly-anteroinferiorly direction. Occasionally the nasal septal cartilage extends more posteriorly interposing itself between the ethmoid and vomer which in some cases never meet .
The anterior septum, at the border between bone portion and cartilage, presents to consider the septal tubercle (or organ of Zuckerkandl), consisting of a rudimental area of erectile tissue .
In addition, the nasal crest of the palatine bone which articulates anteriorly with the nasal crest of the maxilla, together form a horizontal strip of bone, which articulates above with the inferior margin of the vomer.
The greater alar cartilages which form part of the cartilaginous scaffolding of the external nose each have two crura, lateral and medial. The two medial crura are tenuously joined in the midline and together with some intervening soft tissue form the septum mobile nasi at the most anteroinferior margin of the septal cartilage. Anteriorly, the columella is the visible soft tissue portion of the nasal septum that separates the two nares (nostrils) and incorporates the septum mobile nasi.
Arterial supply is via the:
- sphenopalatine artery: a branch of the maxillary artery
- anterior and posterior ethmoidal arteries: branches of the ophthalmic artery
- superior labial artery (anteriorly): a branch of the facial artery
- greater palatine artery (posteriorly): a branch of the maxillary artery
- anterior ethmoidal nerve: posterosuperior septum
- nasal branches of the greater palatine nerve: posteroinferior septum
- nasopalatine nerve, a branch of the maxillary nerve (CN V2): anterior (cartilaginous) septum
Nasal septal deviation is extremely common.
Around the fourth week of gestation, neural crest cells begin to migrate caudally toward the midface. These develop into two symmetrical nasal placodes. Each placode is divided by a nasal pit into a medial and lateral nasal process. The septum develops from the medial processes, along with the premaxilla and philtrum.