International Frontal Sinus Anatomy Classification (IFAC) of Frontal Recess Cells
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👃 International Frontal Sinus Anatomy Classification of Frontal Recess Cells (IFAC)
The International Frontal Sinus Anatomy Classification (IFAC) was published in 2016.
⭐ It classifies the frontal recess cells based on their anatomic origin into three groups, and is more inclusive of the different cells than the earlier Kuhn's classification.
What is the Modified Kuhn's Classification of frontal cells?
Which cells got excluded from Kuhn's Classification?
📋 Groups in the IFAC Classification
⭐ The grouping is based on how the cell pushes the frontal sinus drainage pathway.
| Group | Direction of Displacement of Drainage Pathway | Cells |
|---|---|---|
| Anterior cells | Pushed posteriorly, medially or posteromedially | Agger nasi cell, Supra agger cell, Supra agger frontal cell |
| Posterior cells | Pushed anteriorly | Supra bulla cell, Supra bulla frontal cell, Supraorbital ethmoid cell |
| Medial cell | Pushed laterally | Frontal septal cell |
🔍 Anterior Cells
1- Agger Nasi Cell
🔍 Definition
A cell sitting anterior to the origin of the middle turbinate, or directly above the most anterior insertion of the middle turbinate into the lateral nasal wall.
⭐ It is the most anterior cell seen in the region of the middle turbinate insertion.
2- Supra Agger Cell
🔍 Definition
An anterolateral ethmoid cell lying above the agger nasi cell.
❌ Does not pneumatize into the frontal sinus.
3- Supra Agger Frontal Cell
🔍 Definition
A supra agger cell that pneumatizes into the frontal sinus.
⭐ It has a wide range of sizes, depending on the extent of pneumatization. It may reach only the floor of the frontal sinus, or extend up to its roof.
🔍 Posterior Cells
1- Supra Bulla Cell
🔍 Definition
A cell lying above the bulla ethmoidalis.
❌ Does not enter the frontal sinus.
2- Supra Bulla Frontal Cell
🔍 Definition
A supra bulla cell that pneumatizes along the skull base into the posterior frontal sinus.
3- Supraorbital Ethmoid Cell
🔍 Definition
An anterior ethmoidal cell that pneumatizes over the roof of the orbit, passing anterior or posterior to the anterior ethmoidal artery.
🔍 Medial Cell
Frontal Septal Cell
🔍 Definition
A medially based cell of the anterior ethmoid or the inferior frontal sinus, attached to or located close to the interfrontal sinus septum.
⭐ Being medially placed, it pushes the frontal sinus drainage pathway laterally.
How will you locate the frontal recess cells radiologically?
⭐ High Yield Rapid Revision Table
| Cell | Group | Key Feature |
|---|---|---|
| Agger nasi cell | Anterior | Anterior to the origin of the middle turbinate, or above its most anterior insertion |
| Supra agger cell | Anterior | Anterolateral ethmoid cell above the agger nasi; does not enter the frontal sinus |
| Supra agger frontal cell | Anterior | Supra agger cell pneumatizing into the frontal sinus |
| Supra bulla cell | Posterior | Above the bulla ethmoidalis; does not enter the frontal sinus |
| Supra bulla frontal cell | Posterior | Supra bulla cell pneumatizing along the skull base into the posterior frontal sinus |
| Supraorbital ethmoid cell | Posterior | Pneumatizes over the roof of the orbit, anterior or posterior to the anterior ethmoidal artery |
| Frontal septal cell | Medial | Close to the interfrontal sinus septum |
🧠 Viva Pearls
- IFAC stands for International Frontal Sinus Anatomy Classification, published in 2016.
- IFAC classifies frontal recess cells by their anatomic origin into anterior, posterior and medial groups.
- IFAC is more inclusive of the different cells than Kuhn's classification.
- Anterior cells push the frontal sinus drainage pathway posteriorly, medially or posteromedially.
- Posterior cells push the drainage pathway anteriorly.
- The medial cell pushes the drainage pathway laterally.
- Anterior cells are the agger nasi, supra agger and supra agger frontal cells.
- Posterior cells are the supra bulla, supra bulla frontal and supraorbital ethmoid cells.
- The only medial cell is the frontal septal cell.
- The bulla ethmoidalis itself is not part of the classification.
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