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Anterior ethmoidal air cells

The anterior ethmoidal air cells are a group of small, irregularly shaped, air-filled cavities within the ethmoid bone, forming part of the paranasal sinus system. They lie anterior to the basal lamella of the middle turbinate and contribute to the lateral wall of the nasal cavity and the medial wall of the orbit.

These air cells are highly variable in number and size and are of particular importance in endoscopic sinus surgery, orbital pathology assessment, and sinonasal imaging.

Synonyms

  • Anterior ethmoid cells

  • Anterior ethmoidal sinuses

Location

  • Located within the ethmoid bone

  • Situated anterior to the basal lamella of the middle turbinate

  • Between the nasal cavity medially and the orbit laterally

  • Inferior to the anterior cranial fossa

  • Posterior to the frontal sinus

  • Superior to the maxillary sinus

Anatomical components

  • Multiple small air cells separated by thin bony septa

  • Ethmoid labyrinth (anterior portion)

  • Lateral wall contributors:

    • Lamina papyracea (medial orbital wall)

  • Medial wall contributors:

    • Middle turbinate

    • Lateral nasal wall

Relations

Medially:

  • Nasal cavity

  • Middle turbinate

Laterally:

  • Orbit

  • Lamina papyracea

Superiorly:

  • Anterior cranial fossa

  • Fovea ethmoidalis

Inferiorly:

  • Maxillary sinus

  • Ostiomeatal complex

Posteriorly:

  • Basal lamella of the middle turbinate

  • Posterior ethmoidal air cells

Anteriorly:

  • Frontal recess

  • Frontal sinus drainage pathway

Drainage pathway

  • Drain into the middle meatus of the nasal cavity

  • Via the ethmoidal infundibulum

  • Contribute to the ostiomeatal complex

  • Share drainage pathway with the frontal and maxillary sinuses

X-ray appearance

Paranasal sinus radiographs (Waters / Caldwell views):

  • Appear as multiple small radiolucent areas between the nasal cavity and orbit

  • Poorly resolved due to complex anatomy

  • Best appreciated in Caldwell view

  • Limited sensitivity for detailed evaluation

CT appearance

Non-contrast CT (bone window):

  • Multiple air-filled cavities with thin bony septa

  • Clear delineation of lamina papyracea and fovea ethmoidalis

  • Best modality for anatomical assessment

  • Coronal plane most informative

Post-contrast CT:

  • Air cells: No enhancement

MRI appearance

T1-weighted images:

  • Air-filled cells: Signal void (very low signal)

  • Thin bony walls: Low signal

  • Adjacent orbital fat: High signal

T2-weighted images:

  • Air cells: Signal void

  • Surrounding soft tissues: High signal contrast

CT image

Anterior ethmoidal air cells ct axial

X-Ray image

Anterior ethmoidal air cells X RAY anatomy image -img-00000-00000