Ethmoidal air cells
The ethmoidal air cells (also ethmoidal sinuses or ethmoid sinuses, latin: cellulae ethmoidales) are multiple thin walled cavities located within the ethmoidal labyrinth. They are situated between the upper part of the nasal cavity and the orbit. The orbital plate of the ethmoid separates the ethmoidal air cells from the orbit.
The ethmoidal air cells are subdivided into anterior, middle and posterior groups on each side, which are separated by the basal plate of the middle nasal concha.
- The anterior ethmoidal air cells drain into the middle nasal meatus of the nasal cavity via the ethmoidal infundibulum or the frontonasal duct.
- The middle ethmoidal air cells drain into the middle nasal meatus with an opening located on or superiorly to the ethmoid bulla, a fissure in the lateral wall of the nasal cavity.
- The posterior ethmoidal air cells drain into the superior nasal meatus, usually by a single orifice.
The arterial blood is supplied to the ethmoidal air cells via the following vessels:
- nasal branches of the sphenopalatine artery,
- anterior and posterior ethmoidal branches of the ophthalmic artery.
The venous drainage from the ethmoidal air cells is provided by the sphenopalatine and ophthalmic veins.
The sensory nerve supply to the mucosa lining the ethmoidal air cells is provided by the following nerves:
- anterior and posterior ethmoidal branches of the ophthalmic nerve,
- orbital branches of the pterygopalatine ganglion.