The ethmoid sinus
, one of the paranasal sinuses
, is the collective name for the ethmoidal air cells
Each ethmoid sinus is an air-space enclosed within the ethmoid bone. The ethmoidal air cells consist of numerous thin-walled cavities situated in the ethmoidal labyrinth and completed by the frontal, maxilla, lacrimal, sphenoidal, and palatine bones.
They lie between the upper parts of the nasal cavities and the orbits, and are separated from these cavities by thin bony laminæ.
Anatomically, ethmoidal sinuses can be classified as the anterior, middle, and posterior ethmoid sinuses.
The ethmoidal air cells are by the anterior and posterior ethmoidal nerves
, and the orbital branches of the pterygopalatine ganglion