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Anatomy of the Nose - A Detailed, Simple Explanation

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1. External Nose (The Part You Can See)

Key Landmarks

Skeleton of the External Nose

• Two nasal bones - these are the small rectangular bones you feel at the top of your nose when you press it. Together with the frontal processes of the maxilla (cheek bones), they form the firm upper nose.

• Upper Lateral Cartilages (ULC) - flat, triangular cartilages that form the middle third of the nose. They attach to the nasal bones above (this junction is called the "keystone area" - very important surgically because destroying it can cause the nose to collapse).
• Lower Lateral Cartilages (LLC) - paired, C-shaped cartilages that give the nose tip its shape. Each has:
  • A medial crus (inner limb, forms the columella)
  • A lateral crus (outer limb, forms the nostril rim)
• Sesamoid cartilages - small, accessory cartilages lateral to the LLCs, providing additional support to the nostril walls.

Layers of the Nose Skin (Outside In)

1. S - Superficial fatty layer (attached to dermis)
2. F - Fibromuscular layer (the nasal SMAS - similar to the face's SMAS)
3. D - Deep fatty layer (contains the neurovascular supply)
4. P - Periosteum / perichondrium (directly over bone/cartilage)

The optimal surgical dissection plane is between the deep fatty layer and periosteum because it is relatively avascular and heals with minimal scarring.

Nasal Muscles

• Elevators (shorten nose, dilate nostrils): Procerus, levator labii superioris alaeque nasi
• Depressors (lengthen nose, dilate nostrils): Depressor septi, alar nasalis
• Compressors (lengthen nose, constrict nostrils): Transverse nasalis, compressor narium minor

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2. The Nasal Septum (The Dividing Wall)

Membranous (Mobile) Septum

Keystone Area

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3. Nasal Cavity (The Internal Space)

• Above (roof): Cribriform plate of ethmoid, nasal bones
• Below (floor): Hard palate (maxilla and palatine bones)
• Medially: Nasal septum
• Laterally: Turbinates and paranasal sinus openings

Regions of the Nasal Cavity

1. Vestibule - just inside the nostril, lined by skin and contains vibrissae (nasal hairs) that filter large particles
2. Respiratory region - the main middle area, lined by pseudostratified ciliated columnar epithelium with goblet cells (produces mucus)
3. Olfactory region - the uppermost area near the roof, contains special olfactory neurons for smell

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4. Lateral Wall - The Turbinates (Conchae)

Meatuses (Channels Under Each Turbinate)

Think of the meatuses as "drains" - the sinuses need somewhere to empty their mucus, and these channels are it.

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5. Paranasal Sinuses (Air-Filled Cavities Around the Nose)

• Lighten the skull
• Warm and humidify air
• Add resonance to voice
• Produce mucus to keep the nasal cavity moist

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6. Blood Supply

• Maxillary artery → Sphenopalatine artery (main supply to the nasal cavity)
• Facial artery → Superior labial artery (anteroinferior septum)
• Greater palatine artery (anteroinferior septum via the incisive canal)

• Ophthalmic artery → Anterior ethmoidal artery (upper nasal cavity and septum)
• Ophthalmic artery → Posterior ethmoidal artery (upper posterior cavity)

Kiesselbach's Plexus (Little's Area)

Clinical tip: About 90% of nosebleeds come from Kiesselbach's plexus on the anterior septum.

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7. Nerve Supply

Special Sense - Smell (Olfaction)

• Olfactory nerve (CN I) - special sensory nerve fibres in the olfactory epithelium (roof of nasal cavity) pass through the cribriform plate of the ethmoid to reach the olfactory bulb in the brain.

General Sensation

• Ophthalmic branch of trigeminal nerve (V1) - innervates the upper nose via the anterior and posterior ethmoidal nerves
• Maxillary branch of trigeminal nerve (V2) - innervates the lower and posterior nasal cavity via the sphenopalatine (pterygopalatine ganglion) branches and greater/lesser palatine nerves
• Nasociliary nerve - anterior upper nasal cavity

Autonomic Supply

• Parasympathetic (from facial nerve via vidian nerve): causes nasal secretion and vasodilatation (why your nose runs when you cry or in cold weather)
• Sympathetic (from superior cervical ganglion via vidian nerve): causes vasoconstriction and reduces secretions (how decongestant sprays work)

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8. Nasal Valves (Functional Bottlenecks)

• Internal nasal valve - the angle between the upper lateral cartilage and the nasal septum (should be about 10-15 degrees). This is the main airflow bottleneck.
• External nasal valve - the entrance of the nostril, bounded by the columella, nasal floor, and alar rim.

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9. Functions of the Nose - Putting It All Together

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Quick Summary Diagram - Mental Map

External Nose
  ├── Bony part (upper 1/3): Two nasal bones
  └── Cartilaginous part (lower 2/3): ULC + LLC + sesamoids

Nasal Septum (central dividing wall)
  ├── Front: Quadrangular/septal cartilage
  ├── Upper-back: Perpendicular plate of ethmoid
  └── Lower-back: Vomer

Nasal Cavity (internal space)
  ├── Roof: Cribriform plate → olfactory nerve passes through
  ├── Floor: Hard palate
  ├── Medial wall: Septum
  └── Lateral wall:
        ├── Inferior turbinate → inferior meatus (nasolacrimal duct)
        ├── Middle turbinate → middle meatus (frontal, maxillary, ant. ethmoid sinuses)
        └── Superior turbinate → superior meatus (post. ethmoid)
                              → sphenoethmoidal recess (sphenoid sinus)

Blood Supply
  ├── Sphenopalatine artery (main)
  ├── Anterior & posterior ethmoidal arteries
  └── All meet at Kiesselbach's plexus (Little's area) → most nosebleeds here

Nerve Supply
  ├── CN I (olfactory) → smell
  ├── CN V1 (ophthalmic) → upper nose sensation
  └── CN V2 (maxillary) → lower nose sensation

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• Bailey and Love's Short Practice of Surgery, 28th Edition - Basic Anatomy of the Nose and Paranasal Sinuses
• Cummings Otolaryngology Head and Neck Surgery - Anatomy and Embryology of the Nose
• K.J. Lee's Essential Otolaryngology - Nasal Cavity
• Miller's Anesthesia, 10th Edition - Synopsis of Ear, Nose, and Throat Anatomy