Anatomy of Internal Nose
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Anatomy of Internal Nose
In this post, we explore the internal nose, including its division, the nasal vestibule, nasal valves, and the boundaries of the nasal cavity proper.
🧭 Division of Internal Nose
The internal nose is divided into right and left nasal cavities by the nasal septum (a midline structure).
Each nasal cavity:
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Communicates anteriorly with the external environment via the nares (nostrils)
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Communicates posteriorly with the nasopharynx through the posterior nasal aperture (choana)
👃 Vestibule of the Nose
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Most anterior and inferior part of the nasal cavity
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Lined by keratinized stratified squamous epithelium
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Contains vibrissae (coarse nasal hairs), sebaceous glands, and sweat glands
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Upper limit marked by the limen nasi (nasal valve)
🚪 Nasal Valves
Nasal valves are critical anatomical zones regulating nasal airflow.
They are divided into:
🔹 External Nasal Valve
What are the boundaries of External Nasal Valve?
Clinical Significance:
- Weakness or deformity of any boundary → narrowing or collapse of external nasal valve
- Collapse worsens during inspiration, leading to nasal obstruction
🔹 Internal Nasal Valve
- Narrowest cross-sectional area of the nasal airway
- Key site for resistance regulation during inspiration
What are the boundaries of Internal Nasal Valve?
What is Cottle's test? What does it signify?
🏛 Boundaries of the Nasal Cavity Proper
Each nasal cavity has:
- Roof
- Floor
- Medial wall → Nasal septum
- Lateral wall
🔸 Roof of Nasal Cavity
Formed by:
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Anterior slope → Nasal bones + Nasal spine of frontal bone
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Middle horizontal part → Cribriform plate of ethmoid bone
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Posterior slope → Body of sphenoid bone
What is the surgical importance of the sloping nature of the roof?
🧠 Olfactory Fossa
Olfactory fossa lies above cribriform plate
Formed by:
- Horizontal & vertical lamellae of cribriform plate
- Orbital plate of frontal bone
What is Keros Classification?
What is Gyrus Rectus Sign and which disease do you see it in?
🔸 Floor of Nasal Cavity
- Concave side-to-side, flat anteroposteriorly
- Horizontally oriented
Formed by:
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Anterior ¾ → Palatine process of maxilla
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Posterior ¼ → Horizontal plate of palatine bone
🕳 Incisive Canal (12 mm posterior to anterior floor)
What structures pass through the incisive canal?
Summary
| Region | Key Features |
|---|---|
| Vestibule | Skin-lined, contains vibrissae and sebaceous glands |
| External Nasal Valve | Lateral alar rim, medial septum, inferior nasal sill |
| Internal Nasal Valve | Septum + upper lateral cartilage + head of inferior turbinate |
| Roof | Nasal bones, cribriform plate, sphenoid |
| Floor | Palatine process of maxilla + horizontal palatine bone |
| Olfactory Fossa | Site of olfactory nerve entry, prone to CSF leaks if damaged |
📝 All the topics and questions mentioned in this post are explained in detail in my ENT notes - built for exam success and clinical understanding. Get full access by purchasing the notes.