Nasofrontal canal
The frontal recess is an opening in the inferior aspect of the frontal sinuses that allows drainage of the sinus.
Terminology
The frontal recess is also known as the nasofrontal duct. However, since it does not have bony walls of its own, it is more appropriately referred to as a recess rather than a duct.
Depending on the references, the frontal recess may used synonymously with the term frontal sinus outflow tract/drainage pathway, its lower half, or its upper half.
Gross anatomy
The frontal recess has a variable and relatively complex anatomy depending on the presence of frontal recess cells and bulla lamella. Its appearance has been likened to an inverted funnel with the apex at the frontal ostium. Together with the frontal infundibulum and frontal ostium, it forms the frontal sinus outflow tract or frontal sinus drainage pathway.
It is bordered:
- anteriorly by the frontal recess cells, most commonly the agger nasi cell
- medially by the middle turbinate
- laterally by the medial wall of the orbit
Its posterior margin is variable depending on whether the bulla lamella is complete and whether it reaches the skull base. If present, the suprabullar cell may also contribute to the posterior boundary.
The frontal recess drains into the middle meatus in 62% of cases and into the ethmoid infundibulum in 38%. Direct drainage into the suprabullar and retrobullar recesses is possible when the bulla lamella is incomplete.
Practical points
Patency of the frontal recess depends on the following structures :
- superior articulation of the uncinate process
- agger nasi cells
- presence or absence of frontal recess cells
- supraorbital cell
- bulla lamella
Siehe auch:
