Ethmoid bone

Bone: Ethmoid bone
Cranial bones
The seven bones which articulate to form the orbit. (Ethmoid is brown)
Latin	os ethmoidale
Gray's	subject #36 153
MeSH	Ethmoid+bone

The ethmoid bone (from Greek ethmos, "sieve") is a bone in the skull that separates the nasal cavity from the brain. As such, it is located at the roof of the nose, between the two orbits. The cubical bone is lightweight due to a spongy construction. The ethmoid bone is one of the bones that makes up the orbit of the eye.

Articulations

The ethmoid articulates with fifteen bones:

• four of the neurocranium—the frontal, and the sphenoid (at the sphenoidal body and at the sphenoidal conchae).
• eleven of the viscerocranium—, two Nasal bones, two maxillae, two lacrimals, two palatines, two inferior nasal conchae, and the vomer

Injuries

Fracture of the lamina papyracea, the lateral plate of the ethmoid labyrinth bone, permits communication between the nasal cavity and the ipsilateral orbit through the inferomedial orbital wall, resulting in orbital emphysema. Increased pressure within the nasal cavity, as seen during sneezing, for example, leads to temporary exophthalmos.

Role in magnetoception

Some birds and other migratory animals have deposits of biological magnetite in their ethmoid bones which allow them to sense the direction of the Earth's magnetic field. Humans have a similar magnetite deposit, but it is believed to be vestigial.^{[citation needed]}

Additional images

Ethmoid bone from above.	Perpendicular plate of ethmoid.	Ethmoid bone (frontal view).	Ethmoid bone from the right side.
Sphenoid bone visible center right.	Side view of the skull.	The skull from the front.	Medial wall of left orbit.
Base of the skull. Upper surface.	Medial wall of left nasal fossa.	Roof, floor, and lateral wall of left nasal cavity.	Lateral wall of nasal cavity, showing ethmoid bone in position.
Ethmoid bone

See also

• Ossification of ethmoid
• Bone terminology
• Terms for anatomical location

References

External links

• http://www.theregister.com/2006/11/17/the_odd_body_nose_compass/
• Roche Lexicon - illustrated navigator, at Elsevier 34256.000-1

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.

v • d • e The Bones which form the Orbit Frontal bone • Zygomatic bone • Maxillary bone • Sphenoid bone • Ethmoid bone • Palatine bone • Lacrimal bone