Space
Ethmoidal air cells
Small sinuses between the nasal cavity and orbit
High-yield
Think of two main drainage groups: cells anterior to the middle turbinate's basal lamella reach the middle meatus; posterior cells usually reach the superior meatus. The traditional middle group includes cells associated with the ethmoidal bulla.
Overview
The ethmoidal labyrinth contains many small air spaces separated by thin bony partitions. Their number and extent vary. Anterior and middle cells open into the middle meatus, while most posterior cells drain into the superior meatus. The orbit lies just lateral to the labyrinth and the cranial cavity above it.
Reference facts
- Boundaries
- Lateral nasal wall medially; lamina papyracea and orbit laterally; frontal-bone ethmoidal roof and adjacent cribriform region superiorly.
- Contents
- Variable air cells with respiratory mucosa. Ethmoidal neurovascular canals cross the superior region near the orbital–cranial boundary.
- Communications
- Anterior and middle cells communicate with the middle meatus through openings associated with the infundibulum and bulla; posterior cells usually open into the superior meatus.
- Blood supply
- Mainly anterior and posterior ethmoidal branches of the ophthalmic artery, with regional anastomoses.
- Innervation
- General sensation chiefly through anterior and posterior ethmoidal nerves from nasociliary, CN V1; autonomic fibers serve glands and vessels.
Clinical correlation
Ethmoid infection can spread into the orbit across thin or deficient bone or through venous pathways. Painful eye movement, proptosis and impaired vision raise concern for orbital involvement. The nearby skull base and ethmoidal vessels are also important boundaries in sinus surgery.
Frequently asked questions
What are the boundaries of the ethmoidal air cells?
Lateral nasal wall medially; lamina papyracea and orbit laterally; frontal-bone ethmoidal roof and adjacent cribriform region superiorly.
What do the ethmoidal air cells contain?
Variable air cells with respiratory mucosa. Ethmoidal neurovascular canals cross the superior region near the orbital–cranial boundary.
What do the ethmoidal air cells communicate with?
Anterior and middle cells communicate with the middle meatus through openings associated with the infundibulum and bulla; posterior cells usually open into the superior meatus.