What is the anatomy and function of the lateral wall of the nose?

Anatomy of the Lateral Wall of the Nose

Primary Structural Components

The lateral nasal wall is a complex three-dimensional structure consisting of the turbinates (inferior, middle, and superior), the uncinate process, the ethmoid bulla, and the ostiomeatal complex, which collectively regulate airflow and serve as the primary site of sinus drainage. 1

The Turbinates

• Inferior turbinate: Located on the lateral wall, consists of bone covered with erectile tissue that can enlarge and swell in response to inflammation 1
• Middle turbinate: Positioned superior to the inferior turbinate, with the uncinate process located underneath its posterior portion 1
• Superior turbinate: Visible when deflecting the endoscope superiorly in the sphenoethmoidal recess 1
• The turbinates direct airflow in an anterior-posterior direction and force air flux toward the olfactory organs at the top of the cavity 2

The Uncinate Process and Hiatus Semilunaris

• The uncinate process is located on the lateral nasal wall underneath the posterior portion of the middle turbinate and represents the most anterior portion of the middle meatus 1
• The hiatus semilunaris is the critical space between the uncinate process and the ethmoid bulla 1
• This is typically the first structure removed during endoscopic sinus surgery 1

Sinus Ostia and Drainage Pathways

• Accessory ostia into the maxillary sinus occur in 25-50% of patients, found in the midportion of the lateral nasal wall at the sites of the anterior or posterior fontanelles 1
• The sphenoethmoidal recess contains the sphenoid sinus ostium and posterior ethmoidal ostia 1
• The ostiomeatal complex represents the final common pathway for frontal, maxillary, and anterior ethmoid sinus drainage 3

Vascular Supply

• The sphenopalatine artery provides the dominant blood supply to the lateral nasal wall through the posterior lateral nasal artery 4
• The inferior turbinate artery arises from the lateral nasal wall artery and divides into two branches at the most posterior aspect of the inferior turbinate bone 5
• A smaller-caliber superficial branch travels anteriorly and branches to the lateral nasal wall 5
• The lateral wall branch of the anterior ethmoidal artery and the anterior lateral nasal artery anastomose at the head of the inferior turbinate 4

Functional Significance

Airflow Regulation

• The nasal valve area, formed by the mobile lateral nasal wall, anterior septum, head of the inferior turbinate, and osseous piriform aperture, represents the site of maximum nasal flow resistance 6
• According to Poiseuille's law, even minor constrictions of this area result in clinically relevant impairment of nasal breathing 6
• The main air flux travels along the cavity floor, while turbinate structures direct flow posteriorly 2

Filtration and Air Conditioning

• During passage through the nasal cavity, particles larger than 5-10 μm are filtered out by the lateral wall structures 1
• The lateral wall contributes to warming and humidifying incoming air before it reaches the lungs 1

Clinical Implications

Pathological Conditions

• Inferior turbinate hypertrophy causing airspace restriction requires reduction to restore nasal patency 3
• Lateralization of the middle turbinate can obstruct the middle meatus and compromise sinus drainage 3
• Synechiae formation between the middle turbinate and lateral nasal wall can cause recurrent obstruction 3

Surgical Considerations

• Preservation of periosteal and mucosal attachments of the lateral nasal wall structures minimizes destabilization during surgery 7
• The thickness of the lateral nasal wall at the margin of surgical ostia should be assessed, as thickening may represent inflammatory or polypoid changes 1
• Preservation of as much turbinate tissue as possible is critical to avoid empty nose syndrome 3