Lateral Wall of the Nose

Bony Framework

Fig. 8.242A - Bones of the Lateral Wall of the Nasal Cavity (Gray's Anatomy for Students)

Nasal Conchae (Turbinates)

• Inferior concha - an independent bone (not part of the ethmoid)
• Middle concha - part of the ethmoidal labyrinth
• Superior concha - part of the ethmoidal labyrinth
• (A supreme concha may occasionally be present)

Fig. 8.242B/C - Lateral Wall Covered with Mucosa and Conchae Broken Away Showing Drainage Openings (Gray's Anatomy for Students)

Meatuses (Air Channels)

1. Inferior Meatus

• The largest meatus, lying between the inferior concha and the nasal floor
• Opens into it: The nasolacrimal duct, approximately 1 cm posterior to the head of the inferior turbinate - via a small mucosal fold called Hasner's valve

2. Middle Meatus

• The most clinically important meatus
• Contains the ethmoidal bulla (dome-shaped elevation formed by underlying middle ethmoidal cells) and the semilunar hiatus (a curved gutter inferior to the bulla)
• The ethmoidal infundibulum leads from the anterior end of the semilunar hiatus upward into the frontonasal duct and frontal sinus
• Opens into it: Frontal sinus (via frontonasal duct/ethmoidal infundibulum), maxillary sinus (at the floor of the semilunar hiatus), middle and anterior ethmoidal cells (on/above the ethmoidal bulla)
• The middle meatus is thus the common drainage pathway for the frontal, maxillary, and anterior ethmoid sinuses - collectively called the ostiomeatal complex (OMC)

3. Superior Meatus

• Smaller, between the superior and middle conchae
• Opens into it: Posterior ethmoidal air cells

4. Spheno-ethmoidal Recess

• The space above and posterior to the superior concha
• Opens into it: Sphenoidal sinus (the only paranasal sinus not opening onto the lateral wall proper)

Blood Supply

Vascular supply of the lateral nasal wall - Scott-Brown's Otorhinolaryngology

Nerve Supply

• Secretomotor (parasympathetic): Presynaptic fibers travel in the vidian nerve (greater superficial petrosal nerve component) and synapse in the sphenopalatine ganglion to innervate nasal mucous glands
• Vasomotor (sympathetic): Postsynaptic fibers from the deep petrosal nerve pass through the sphenopalatine ganglion and regulate vascular tone and turbinate congestion

Gateways to the Lateral Wall

Clinical Relevance

• Ostiomeatal complex (OMC): The middle meatus and its associated drainage pathways are collectively the OMC - obstruction here leads to chronic rhinosinusitis involving the frontal, maxillary, and anterior ethmoid sinuses
• Epistaxis: The sphenopalatine artery is the most common target for endoscopic ligation in posterior epistaxis. The crista ethmoidalis is the key surgical landmark
• Turbinate hypertrophy: A common cause of nasal obstruction due to allergic or non-allergic rhinitis
• Nasolacrimal duct obstruction: Presents with epiphora; the duct opens under the anterior lip of the inferior concha

Medial Wall of the Nose (Nasal Septum)

Diagrams

Fig. 8.239 - Medial Wall of the Nasal Cavity - the Nasal Septum (Gray's Anatomy for Students)

The cartilaginous and bony components of the nasal septum (Scott-Brown's Otorhinolaryngology)

The left side of the nasal septum - Bailey and Love's

Composition of the Nasal Septum

1. Bony Part

2. Cartilaginous Part

• Bound firmly to nasal bones, perpendicular plate of ethmoid, and vomer by collagenous fibers
• Continuous with the upper lateral cartilages at the bridge of the nose
• Its sphenoidal process (septal tail) extends posteriorly between the vomer and perpendicular plate - a useful graft source during revision rhinoplasty
• Inferior attachment to the nasal crest of the maxilla is via looser connective tissue (a pseudoarthrosis), allowing mobility during trauma to reduce the risk of fracture
• Anteroinferiorly, a small vomeronasal (Jacobson's) cartilage may be present along the nasal floor

3. Membranous Part

• A small segment of connective tissue between the caudal edge of the septal cartilage and the columella
• Forms the mobile, soft lower part of the septum

Summary of Bony Framework

ANTEROSUPERIOR         POSTEROSUPERIOR
Nasal spine of         Perpendicular plate
frontal bone           of ethmoid
       ↓                      ↓
  Nasal bone            Rostrum of sphenoid
       ↓                      ↓
Septal cartilage ←---→  Vomer (posterior + inferior)
       ↓
Nasal crest of maxilla + palatine bone (floor)
       ↓
  Incisive canal

Blood Supply

Arterial blood supply to the left side of the nasal septum - showing Kiesselbach's plexus (Bailey and Love's)

Kiesselbach's Plexus (Little's Area)

• Posterior septal branch of sphenopalatine artery
• Anterior ethmoidal artery
• Greater palatine artery
• Alar branch of superior labial artery (facial artery)

Venous Drainage

• Anterior and posterior ethmoidal veins → superior ophthalmic vein → cavernous sinus
• Sphenopalatine vein → pterygoid plexus
• Facial vein

Clinical point: Because nasal veins are valveless, retrograde spread of infection to the cavernous sinus is possible - this is why nasal sepsis (especially "danger triangle" infections) can be life-threatening.

Nerve Supply

Sensory

Autonomic

Functions of the Nasal Septum

1. Divides the nasal airway into two separate nasal cavities
2. Supports the nasal dorsum
3. Maintains the nasal tip projection
4. Forms part of the internal and external nasal valves (regulation of airflow)
5. Source of cartilage graft in rhinoplasty and reconstructive surgery

Clinical Points