Skeletal System:- Neurocranium - Ethmoid bone

Anatomy of Ethmoid Bone, an unpaired bone of the skull that contributes to the medial wall of the orbit, the nasal cavity and the nasal septum.

1. Ethmoid
Bone
Skeletal System
Neurocranium
Dr. Aves Khan
Oral & Dental
Surgeon

2. Introduction of
Ethmoid Bone
Theethmoidboneisanunpairedboneoftheskullthatcontributesto
themedialwalloftheorbit,thenasalcavityandthenasalseptum.
Theethmoidboneincludesthecribriformplatewithopeningsthat
transmittheolfactorynerves(CNI),anditalsohousesparanasalsinuses
calledtheethmoidalaircells.

3. Parts of
Ethmoid Bone
The ethmoid bone has 4 parts –
1.Cribriform plate
2.Perpendicular plate
3.One pair of ethmoidal labyrinth

4. Cribriform plate
of ethmoid
Itissituatedinthehorizontalplane,coveringtheethmoidal
incisure.
Itformstheroofofthenasalcavityandpartoftheanterior
cranialfossaoftheinternalcranialbase.
Thecribriformplatehassmallopeningswhichtransmitthefibers
oftheolfactorynerves(CNI)fromtheolfactoryepithelium
(nasalcavity)tothebrain(cranialcavity).

5. Perpendicular
plate of ethmoid
Itissituatedinthesagittalplanebelowthecribriformplate.
Thelowerpartoftheperpendicularplateformstheposterior
nasalseptum,whiletheupperpartrisesabovethecribriformplate
asthecristagalli.

6. Ethmoidal
labyrinth
It is situated in the sagittal plane below the lateral margin of the
cribriform plate of theethmoid.
The ethmoidal labyrinth separates the orbit from the nasal cavity.
The ethmoidal labyrinth of theethmoidfeatures several
structures:
1.ethmoidal air cells (anterior, middle, posterior),
2.orbital plate,
3.superior nasal concha,
4.middle nasal concha.

7. Theethmoidalaircellsareairfilledspacesintheethmoidal
labyrinthoftheethmoidbonebelongingtotheparanasalsinuses.
Therecanbedistinguishedanterior,middle,andposterior
ethmoidalaircells.
Theorbitalplateoftheethmoidallabyrinthisathinbonyplate
foundintheethmoidbone,coveringtheethmoidalcellsfromthe
orbitalsideandformingthelateralsurfaceofthelabyrinth.
Thenasalconchaearecurvedbonyplates,whichformthe
passagesofthenasalcavity-thenasalmeatuses.
Theconchascovertheethmoidalcellsfromthesideofthenasal
cavityformingthemedialsurfaceofthelabyrinth.
Ethmoidal labyrinth
-Structures

8. Anatomical
views of the
Ethmoid bone
Lateral View
Posterior View

9. Anatomical
views of the
Ethmoid bone
Anterior View
Inferior View

10. Dr. Aves Khan
Oral & Dental
Surgeon