Ethmoid Bone Structure and Function

Ethmoid Bone Characteristics

• The ethmoid bone is a porous bone that forms the major portion of the middle part of the face between the orbits.
• It helps form the orbit, nasal cavity, nasal septum, and anterior cranial fossa.
• There is only one ethmoid bone.

Parts of the Ethmoid Bone

Perpendicular Plate

• A flat plate that descends from the cribriform plate to form part of the nasal septum.
• It articulates with the vomer inferiorly.

Cribriform Plate

• A horizontal bone that forms the superior surface of the ethmoid.
• It contains numerous foramina for the olfactory nerve.
• The crista galli is a vertical plate that extends superiorly from the cribriform plate, providing attachment for the falx cerebri of the meninges.
• It is associated with a small foramen cecum.

Ethmoid Labyrinth

• The largest part of the ethmoid bone.
• It descends inferiorly from the cribriform plate.
• The ethmoid paranasal sinuses are located within the ethmoid labyrinth.
• The ethmoid labyrinth forms two major structures within the nasal cavity:
  • Superior nasal concha.
  • Middle nasal concha.
• The ethmoid bulla is a large elevation of bone located near the middle ethmoid paranasal sinuses.
• The uncinate process is a curved piece of bone.
• The hiatus semilunaris is located between the uncinate process and the ethmoid bulla.

Ethmoid Bone Characteristics

• The ethmoid bone is a porous bone that forms the major portion of the middle part of the face between the orbits.
• It helps form the orbit, nasal cavity, nasal septum, and anterior cranial fossa.
• There is only one ethmoid bone.

Parts of the Ethmoid Bone

Perpendicular Plate

• A flat plate that descends from the cribriform plate to form part of the nasal septum.
• It articulates with the vomer inferiorly.

Cribriform Plate

• A horizontal bone that forms the superior surface of the ethmoid.
• It contains numerous foramina for the olfactory nerve.
• The crista galli is a vertical plate that extends superiorly from the cribriform plate, providing attachment for the falx cerebri of the meninges.
• It is associated with a small foramen cecum.

Ethmoid Labyrinth

• The largest part of the ethmoid bone.
• It descends inferiorly from the cribriform plate.
• The ethmoid paranasal sinuses are located within the ethmoid labyrinth.
• The ethmoid labyrinth forms two major structures within the nasal cavity:
  • Superior nasal concha.
  • Middle nasal concha.
• The ethmoid bulla is a large elevation of bone located near the middle ethmoid paranasal sinuses.
• The uncinate process is a curved piece of bone.
• The hiatus semilunaris is located between the uncinate process and the ethmoid bulla.

Learn about the characteristics, parts, and functions of the ethmoid bone, including its role in forming the orbit, nasal cavity, and nasal septum.