Irregular due to 3 curved shelf-like projections — conchae (turbinates). Separates nose from orbit (above, with ethmoidal sinuses intervening), maxillary sinus (below), lacrimal groove + nasolacrimal canal (front).

Bony Skeleton (7 bones, anterior → posterior)

Nasal bone → frontal process of maxilla → lacrimal bone → labyrinth of ethmoid (with superior + middle conchae) → inferior nasal concha (independent bone) → perpendicular plate of palatine → medial pterygoid plate of sphenoid

Three Conchae

4th concha (concha suprema) may occasionally be present above superior concha

Meatuses (Passages Below Conchae)

Inferior Meatus

• Largest meatus; under inferior concha
• Opening: nasolacrimal duct (junction of anterior 1/3 and posterior 2/3); guarded by Hasner’s valve (lacrimal fold)

Middle Meatus (Most Important)

• Under middle concha; most sinuses drain here

Features:

Openings in middle meatus:

Mnemonic: FAMS — Frontal, Anterior ethmoidal, Middle ethmoidal (on bulla), Maxillary (posterior hiatus)

Superior Meatus

• Under superior concha; smallest + shallowest
• Opening: Posterior ethmoidal air sinuses

Sphenoethmoidal Recess

• Above + behind superior concha
• Opening: Sphenoidal air sinus

Summary — Sinus Openings

Anterior group (drain into middle meatus): Frontal + Anterior ethmoidal + Middle ethmoidal + Maxillary Posterior group (do NOT drain into middle meatus): Posterior ethmoidal + Sphenoidal

Lining

Respiratory mucosa: cavernous sinusoids (erectile tissue) → swells in rhinitis → nasal blockage; cilia sweep mucus posteriorly → swallowed

Arterial Supply

Nerve Supply

Autonomic (Vidian nerve → pterygopalatine ganglion): Parasympathetic = secretomotor to nasal glands; Sympathetic = vasoconstriction

Lymphatic Drainage

• Anterior half → submandibular nodes
• Posterior half → retropharyngeal + upper deep cervical nodes

Applied Anatomy

• Rhinitis — inferior concha swells → nasal blockage; allergic/vasomotor rhinitis → excessive rhinorrhoea → controlled by sectioning Vidian nerve
• Woodruff’s area — vascular area under posterior end of inferior concha → site of posterior epistaxis (elderly, hypertensives)
• Maxillary sinusitis — maxillary ostium near roof (not floor) of sinus → poor natural drainage → recurrent infection; pain to upper teeth + infraorbital skin (V2)
• Nasolacrimal duct obstruction → epiphora; also by medial maxillary sinus carcinoma invasion
• Ethmoidal sinusitis — lamina papyracea (paper-thin bone) separates ethmoid from orbit → easy spread → orbital cellulitis
• Sphenoidal sinusitis — superior relation to pituitary + optic chiasma; lateral to cavernous sinus + ICA → visual disturbance, pituitary dysfunction, cavernous sinus thrombosis

Overview

The lateral wall of the nasal cavity is irregular due to the presence of three curved, shelf-like bony projections called conchae (turbinates). It separates the nose from:

• Above: orbit, with ethmoidal air sinuses intervening
• Below: maxillary sinus
• In front: lacrimal groove and nasolacrimal canal

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Skeleton of the Lateral Wall

Bony Components (7 bones — anterior to posterior)

Cartilaginous Components

• Superior nasal cartilage (lateral nasal cartilage / upper alar cartilage)
• Inferior nasal cartilage (lower alar cartilage / major alar cartilage)
• 3–4 small minor alar cartilages

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Three Regions of the Lateral Wall

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Conchae (Turbinates)

Curved bony projections directed downwards and medially. They greatly increase the surface area for air conditioning.

A 4th concha (concha suprema) may occasionally be present above the superior concha.

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Meatuses

Passages (recesses) beneath the overhanging conchae — best seen after conchae are removed.

Inferior Meatus

• Largest of the three meatuses
• Lies underneath the inferior nasal concha
• Opening: Nasolacrimal duct opens at the junction of anterior one-third and posterior two-thirds of the inferior meatus
• Opening guarded by Hasner’s valve (lacrimal fold)

Middle Meatus

• Lies underneath the middle nasal concha
• Most important meatus — receives openings of the largest number of sinuses

Features of the middle meatus:

Openings in the middle meatus:

Mnemonic for middle meatus openings: “FAMS” — Frontal, Anterior ethmoidal, Middle ethmoidal (on bulla), Maxillary (posterior hiatus)

Superior Meatus

• Lies underneath the superior nasal concha
• Smallest and shallowest
• Opening: Posterior ethmoidal air sinuses

Sphenoethmoidal Recess

• Triangular depression above and behind the superior concha
• Opening: Sphenoidal air sinus

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Summary Table — Sinus Openings

Anterior group sinuses (drain into middle meatus): Frontal + Anterior ethmoidal + Middle ethmoidal + Maxillary Posterior group sinuses (do NOT drain into middle meatus): Posterior ethmoidal + Sphenoidal

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Lining of the Nasal Cavity

Respiratory mucosa contains cavernous sinusoids (erectile tissue) — swell during rhinitis causing nasal blockage. Cilia sweep mucus posteriorly into the nasopharynx where it is swallowed.

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Arterial Supply of the Lateral Wall

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Venous Drainage

Veins form a submucosal plexus draining into:

• Anteriorly — facial vein
• Middle — pterygoid venous plexus
• Posteriorly — pharyngeal venous plexus

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Nerve Supply of the Lateral Wall

General Sensory (Somatic) — by quadrant

Special Sensory

• Olfactory nerve rootlets (CN I) — upper part of lateral wall just below cribriform plate, up to superior concha

Autonomic

• Vidian nerve (nerve of pterygoid canal) → pterygopalatine ganglion:
  • Parasympathetic: secretomotor to nasal glands (controls nasal secretion)
  • Sympathetic: vasoconstrictors

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Lymphatic Drainage

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Clinical Correlations

Rhinitis (Common Cold): Commonest infection of the nasal cavity. Mucosal swelling of inferior concha → nasal blockage. In allergic/vasomotor rhinitis, excessive rhinorrhoea can be controlled by sectioning the Vidian nerve.

Woodruff’s Area: Vascular area under the posterior end of the inferior concha — site of posterior epistaxis (in elderly and hypertensives), as opposed to anterior epistaxis from Little’s area on the septum.

Maxillary Sinusitis: Commonest paranasal sinus infection. The maxillary ostium opens near the roof (not floor) of the sinus → poor natural drainage → recurrent infection. Pain referred to upper teeth and infraorbital skin (maxillary nerve).

Nasolacrimal Duct Obstruction: The duct opens into the inferior meatus. Obstruction → epiphora (overflow of tears). Also obstructed by medial invasion of maxillary sinus carcinoma.

Spread of Ethmoidal Sinusitis: Ethmoidal sinuses are separated from the orbital cavity by only the lamina papyracea (paper-thin bone) — infection spreads easily into the orbit → orbital cellulitis.

Sphenoidal Sinusitis: Related superiorly to the pituitary gland and optic chiasma; laterally to the cavernous sinus and internal carotid artery — spread of infection can cause visual disturbance, pituitary dysfunction, or cavernous sinus thrombosis.

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