Ethmoid bone

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Bone: Ethmoid bone

Sagittal section of skull. (Ethmoid bone visible as white structure to left.)

Lateral wall of nasal cavity, showing ethmoid bone in position.
Latin	os ethmoidale
Gray's	subject #36 153

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.

1 Parts
2 Articulations
3 Injuries
4 Role in magnetoception
5 Additional images
6 See also
7 External links

[edit] Parts

The ethmoid bone consists of four parts:

the horizontal Cribriform plate (lamina cribrosa), part of the cranial base
the vertical Perpendicular plate (lamina perpendicularis), which is part of the nasal septum
the two lateral masses or labyrinths.

[edit] Articulations

The ethmoid articulates with fifteen bones: four of the cranium—the frontal, the sphenoid, and the two sphenoidal chonchae; and eleven of the face—the two nasals, two maxillae, two lacrimals, two palatines, two inferior nasal conchae, and the vomer.

[edit] Injuries

The ethmoid bone is very delicate and is easily injured by a sharp upward blow to the nose, such as a person might suffer by striking an automobile dashboard in a collision. The force of a blow can drive bone fragments through the cribiform plate into the meninges or brain tissue. Such injuries are often evidenced by leakage of cerebrospinal fluid into the nasal cavity, and may be followed from the nasal cavity to the brain.

Blows to the head can also shear off the olfactory nerves that pass though the ethmoid bone and cause anosmia, an irreversible loss of the sense of smell and a great reduction in the sense of taste (most of which depends on smell). This not only deprives life of some of its pleasures, but can also be dangerous, as when a person fails to smell smoke, gas, or spoiled food.

[edit] Role in magnetoception

Main article: 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]}

[edit] Additional images

Cranial bones	Sphenoid bone visible center right.	Side view of the skull.	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.

[edit] See also

[edit] External links

http://www.theregister.com/2006/11/17/the_odd_body_nose_compass/

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.

Human Bones

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