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Nasal cavity

The nasal cavity is the air-filled space within the nose that forms the initial segment of the respiratory tract. It extends from the nares anteriorly to the choanae posteriorly, where it communicates with the nasopharynx. The cavity is divided into right and left halves by the nasal septum and lined by specialized mucosa that conditions inspired air through warming, humidification, and filtration.

Anatomically, the nasal cavity is divided into the vestibule and the nasal cavity proper. The cavity proper contains the superior, middle, and inferior turbinates, which increase surface area and regulate airflow. Superiorly, it is related to the anterior cranial fossa, and laterally it communicates with the paranasal sinuses.

Synonyms

  • Cavum nasi

  • Nasal passage

Location and Structure

  • Anterior boundary: Nostrils (nares)

  • Posterior boundary: Choanae opening into nasopharynx

  • Medial wall: Nasal septum (septal cartilage, perpendicular plate of ethmoid, vomer)

  • Lateral wall: Maxilla, lacrimal bone, ethmoid labyrinth, inferior turbinate

  • Roof: Nasal bone, frontal bone, cribriform plate of ethmoid, sphenoid body

  • Floor: Hard palate (palatine process of maxilla and horizontal plate of palatine bone)

Subdivisions

  • Nasal vestibule: Lined by skin, contains vibrissae and sebaceous glands

  • Nasal cavity proper: Lined by respiratory epithelium (and olfactory epithelium superiorly)

  • Turbinates (conchae):

    • Inferior turbinate (separate bone)

    • Middle and superior turbinates (parts of ethmoid bone)

Relations

  • Superiorly: Anterior cranial fossa and olfactory bulb

  • Inferiorly: Oral cavity and hard palate

  • Laterally: Maxillary, ethmoidal, frontal, and sphenoidal sinuses

  • Posteriorly: Nasopharynx

  • Anteriorly: External nose

Function

  • Air conditioning: Warms, humidifies, and filters inspired air

  • Olfaction: Superior nasal cavity contains olfactory epithelium

  • Resonance: Contributes to voice resonance

  • Defense: Traps particles and pathogens via mucociliary clearance

MRI Appearance (Normal)

T1-weighted images:

  • Air-filled cavity: Very low signal (black)

  • Nasal septum cartilage: Intermediate signal

  • Turbinates: Intermediate signal soft tissue

  • Bone: Very low signal cortical margins

  • Fat (vestibule/subcutaneous): Bright signal

T2-weighted images:

  • Air: Signal void (black)

  • Mucosa and turbinates: Intermediate-to-mildly hyperintense

  • Cartilage: Intermediate signal

  • Bone: Low signal

  • Secretions (physiologic thin layer): Mildly hyperintense

STIR:

  • Air: Black

  • Normal mucosa: Intermediate-to-dark signal

  • Turbinates: Intermediate signal with clear margins

  • Fat: Suppressed

  • Highlights normal soft-tissue anatomy without pathological edema

T1 Fat-Saturated Post-Contrast:

  • Nasal mucosa: Uniform, thin enhancement

  • Turbinates: Symmetric homogeneous enhancement

  • Septal cartilage: Minimal enhancement

  • Bone and air: No enhancement

  • Demonstrates normal vascularity of nasal lining

CT Appearance (Normal)

Non-Contrast CT:

  • Air-filled nasal cavity: Very low attenuation

  • Bones: High attenuation with sharp cortical margins

  • Nasal septum: Clearly visualized osseous and cartilaginous components

  • Turbinates: Soft-tissue density projecting from lateral walls

  • Ostiomeatal region: Normally patent

  • Best modality for evaluating bony anatomy and anatomic variants

Post-Contrast CT:

  • Nasal mucosa and turbinates: Mild, symmetric enhancement

  • Bone: No enhancement

  • Air spaces: Remain non-enhancing

  • Useful for confirming normal mucosal vascularity and anatomy

X-Ray Appearance (Plain Radiography)

  • Nasal cavity: Appears as a radiolucent (dark) air-filled space

  • Nasal septum: Thin vertical radiopaque line in midline (best on frontal view)

  • Inferior turbinates: Faint soft-tissue shadows along lateral walls

  • Bones: Nasal bones and maxilla appear radiopaque

MRI image

Nasal cavity mr anatomy labelled image-img-00000-00000

CT image

Nasal cavity CT anatomy labelled image-img-00000-00000