Ethmoid bone

Function

A delicate, air-filled labyrinth separating the orbits and forming the roof of the nasal cavity. Olfactory nerves pierce its cribriform plate for the sense of smell, and its conchae swirl inspired air to warm, humidify and filter it.

Landmarks

• Cribriform plate
• Crista galli
• Perpendicular plate
• Superior and middle nasal conchae
• Ethmoid air cells
• Ethmoidal foramina

Articulations (joints)

• Frontal bone
• Sphenoid bone
• Nasal bones
• Maxillae
• Lacrimal bones
• Palatine bones
• Vomer
• Inferior nasal conchae

Clinical relevance

Ethmoid fractures tear the overlying dura, allowing CSF to drip from the nose. Ethmoid sinusitis can spread into the orbit, causing orbital cellulitis and threatened vision.