Ethmoid bone

Dr Jeremy Jones et al.

The ethmoid bone is a single midline facial bone that separates the nasal cavity from the brain and is located at the roof of the nose and between the two orbits. It is a cubical shape and is relatively lightweight because of its spongy construction. It contributes to the anterior cranial fossa.

Gross anatomy

The ethmoid bone consists of four parts:

  • horizontal (cribriform) plate
  • vertical (perpendicular) plate
  • 2 lateral masses (labyrinths)

The horizontal plate features include:

  • foramina in cribiform plate: for olfactory nerve filaments (20), olfactory bulb overlies
  • crista galli (Latin for rooster's crest): thick, smooth triangular process, attachment for falx cerebri
  • nasal slits: anteriorly, passage of anterior ethmoidal nerve

The vertical plate forms the nasal septum:

  • anterior border articulates with frontal bone and crests of nasal bones
  • posterior border features the sphenoidal crest which articulates with the vomer

Labyrinths (2)  house anterior, middle, posterior ethmoidal cells.

  • lateral surface features include: the orbit, lamina papyracea, uncinate process below: medial wall of maxillary sinus which articulates with inferior conchae
  • medial surface features include: the nasal cavity, superior nasal concha, middle nasal concha helps form middle meatus, and the infundibulum opens there 
  • upper surface: grooves articulate with frontal bone to form anterior and posterior ethmoidal canals
Articulations

Articulates with 15 bones in total (4 cranial bones, and 11 facial bones)

Cranial bones include frontal, sphenoid, and sphenoidal conchae (2). The facial bones are paired or unpaired. The single unpaired (1) bone is the vomer. Paired bones (2) include nasal, maxilla, lacrimals, palatines, inferior nasal conchae.

Head and neck anatomy
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Article information

rID: 4785
System: Head & Neck
Section: Anatomy
Synonyms or Alternate Spellings:

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Cases and figures

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    Figure 1: sagittal section of the skull
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    Figure 2: orbital bones
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    Figure 3
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    Figure 4: posterior view
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    Ethmoid bone. Ima...
    Figure 5: skull and facial bones
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