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Ethmoid Bone Anatomy

Introduction to Ethmoid bone anatomy:

  • The image descriptionethmoid bone (Gr., ethmos – sieve) is a spongy, cuboid-shaped cranial bone located at the top of the nasal cavity and between the two orbits.
Four views of the ethmoid bone.
Four views of the ethmoid bone.
Four views of the ethmoid bone.
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  • It primarily consists of two lateral masses (containing the ethmoid air cells or ethmoid sinuses) and several projections that extend into the nasal cavity and cranial floor.

Markings of the Ethmoid Bone:

  1. Orbital plate (or orbital lamina, lami-na papyracea) – thin plate along the lateral margin of the ethmoid labyrinth (or lateral mass); forms part of the medial wall of the orbit. [image descriptionCoronal view /image descriptionOrbital view ]
The orbital plate.
The orbital plate labeled.
The orbital plate labeled and highlighted.
The orbital plate labeled.
The orbital plate highlighted and labeled.
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  1. Perpendicular plate – thin vertical plate that extends down into nasal cavity; articulates with vomer bone to form bony nasal septum. [image descriptionAnterior view /image descriptionCoronal view /image descriptionSagittal view ]
Anterior view of the perpendicular plate
Anterior view of the perpendicular plate
Anterior view of the perpendicular plate highlighted and labeled
Coronal view of the perpendicular plate
Coronal view of the perpendicular plate highlighted and labeled
Midsagittal view of the perpendicular plate
Midsagittal view of the perpendicular plate highlighted and labeled
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  1. Middle turbinate (or middle concha, plural = conchae) – thin plate that extends down into nasal cavity lateral to perpendicular plate; covered with mucous membrane, which warms, moistens, and cleans inhaled air. [image descriptionCoronal view /image descriptionAnterior view ]
Coronal view of the middle turbinate.
Coronal view of the middle turbinate.
Coronal view of the middle turbinate highlighted and labeled.
Anterior view of the middle turbinate.
Anterior view of the middle turbinate highlighted and labeled.
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  1. Superior turbinate – (or superior con-cha) – short, thin, plate that extends down into the nasal cavity just above the middle turbinate; serves same functions as middle turbinate. [image descriptionCoronal view ]
Coronal view of the superior turbinate.
Coronal view of the superior turbinate.
Coronal view of the superior turbinate highlighted and labeled.
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  1. Lateral mass (or ethmoid labyrinth) – region of bone lateral to perpendicular plate; contains many mucous-lined air cells (the ethmoid sinuses) that open into nasal cavity.  [image descriptionCoronal view ]
Coronal view of the lateral mass.
Coronal view of the lateral mass.
Coronal view of the lateral mass highlighted and labeled.
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  1. Cribriform plate (L., cribum =  sieve) –  a horizontal plate (or lamina) in cranial floor and roof of nasal cavity that articulates with the frontal bone. [image descriptionCoronal view /image descriptionSagittal view /image descriptionCranial floor view]
Coronal view of the cribriform plate.
Coronal view of the cribriform plate.
Coronal view of the cribriform plate highlighted and labeled.
Midsagittal view of the cribriform plate.
Midsagittal view of the cribriform plate highlighted and labeled.
Cranial floor view of the cribriform plate.
The cribriform plate highlighted and labeled.
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  1. Crista galli (or L. crest of the cock) – thin vertical plate that extends up from  cribiform plate; attachment point for the falx cerebri (= part of the connective tissues that surround and protect the brain). [image descriptionCoronal view /image descriptionCranial floor view /image descriptionSagittal view ]
Coronal view of the crista galli.
Coronal view of the crista galli.
Coronal view of the crista galli highlighted and labeled.
Cranial floor view of the crista galli.
Cranial floor view of the crista galli highlighted and labeled.
Sagittal view of the crista galli.
The crust galli highlighted and labeled.
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Test yourself:

Anterior view: image descriptionShow/Hide answers

 

Test yourself on anterior view.
Test yourself on anterior view.
Test yourself on anterior view.
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Coronal view: image descriptionShow/Hide answers

Test yourself on coronal view.
Test yourself on coronal view.
Test yourself on coronal view.
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Midsagittal view: image descriptionShow/Hide answers

Test yourself on midsagittal view.
Test yourself on midsagittal view.
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Cranial Floor view: image descriptionShow/Hide answers

Test yourself on cranial floor view.
Test yourself on cranial floor view.
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