Ethmoid bone

Ethmoid Bone AR Atlas

The Ethmoid bone articulates with (1):

• The Frontal Bone
• The Sphenoid Bone
• The Vomer
• The2 Inferior Nasal Concha
• The Palatine Bones
• The Lacrimal Bones
• The Nasal Bones
• The Maxilae Bones

Ethmoid bone: The ethmoid bone is unpaired, shaped as a cube, and positioned between the orbits. It comprises four parts: cribriform plate, perpendicular plate, and 2 Labyrinths. (1)

Cribriform plate

• Cribriform plate: The cribriform plate is the horizontal part of the bone. Received in the ethmoidal notch of the frontal bone, it is deeply grooved and supports the olfactory bulb. (1)
  • Cribriform foramina: The cribriform foramina are holes in the cribriform plates that give passage to nerves of the olfactory bulb. (1)
• Crista Galli: The crista galli is a bony projection located on the midline of the cribriform plate. It gives attachment to the falx cerebri. (1)
• Ala of crista galli: The ala of crista galli are located on the anterior border of crista gali. They articulate with the frontal bone. (1)

Perpendicular plate of ethmoid bone

• Perpendicular plate of ethmoid bone: The perpendicular plate of ethmoid bone is a thin bony plate that originates on the inferior surface of the cribriform plate. (1)

Ethmoidal labyrinth

Ethmoidal labyrinth: Ethmoidal labyrinths are two lateral masses located parallel on either side to the perpendicular plate. There are thin-walled air-filled cavities present in the labyrinth. (1)

• Cells of ethmoid bone: They are multiple chambers located within the ethmoidal labyrinth grouped into three main groups. The anterior cells, the middle cells, and the posterior cells. (1)
  • Anterior cells of ethmoid bone: The anterior cells of the ethmoid bone are the most anterior group of ethmoidal cells present in the perpendicular plate. The lacrimal bone covers them. (1)
  • Middle cells of ethmoid bone: The middle cells of the ethmoid bone are the ethmoidal cells located between the anterior and posterior groups. Situated in the ethmoidal labyrinth, they are covered by the orbital plate of the ethmoid bone. (1)
  • Posterior cells of ethmoid bone: The posterior cells of ethmoid bone are the most posterior group of ethmoidal cells present in the ethmoid bone. The orbital plate of the ethmoid bone covers them. (1)

• Orbital plate of ethmoidal labyrinth: Orbital plate of ethmoidal labyrinth is a thin bony plate that covers the middle and the posterior cells of the ethmoid bones and takes part in the formation of the medial wall of the orbit. (1)
• Bony ethmoidal bulla: The bony ethmoidal bulla is a notable and enlarged structure found in the ethmoid bone. (24)
• Uncinate process of ethmoid bone: The uncinate process of the ethmoid bone is a curved lamina positioned anteriorly that descends posteroinferiorly. It articulates with the ethmoidal process of the inferior nasal concha. (1)
• Bony ethmoidal infundibulum: The bony ethmoidal infundibulum is a passage that opens into the middle ethmoidal cells (1)
• Bony semilunar hiatus: The bony semilunar hiatus is a space between the ethmoidal bulla’s anterior wall and the uncinate process’s free edge. (20)

• Bony superior nasal concha: The bony superior nasal concha is a thin curved plate positioned superiorly on the medial surface of the ethmoid bone. (1)
• Bony middle nasal concha: The bony middle nasal concha is the inferior convoluted margin of the medial surface of the labyrinth of the ethmoid bone. (1)

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The structure and organization of anatomical terms used in this text follow the guidelines provided by FIPAT (2019) in their publication: FIPAT. (2019). Terminologia Anatomica (2nd ed.). FIPAT.library.dal.ca. Federative International Programme for Anatomical Terminology. Retrieved May 7, 2023, from https://fipat.library.dal.ca/TA2/