Ethmoid sinus

Bone: Ethmoid sinus
Paranasal sinuses
Coronal section of nasal cavities.
Latin	cellulae ethmoidales
Gray's	subject #36 154
MeSH	Ethmoid+Sinus

The ethmoid sinuses of the ethmoid bone are two of the four paired paranasal sinuses. They are composed of a variable number of air cells and divided into the anterior, middle and posterior groups. The ethmoidal air cells consist of numerous thin-walled cavities situated in the ethmoidal labyrinth and completed by the frontal, maxilla, lacrimal, sphenoidal, and palatine bones. They lie between the upper parts of the nasal cavities and the orbits, and are separated from these cavities by thin bony laminae.

Three groups

The groups of the ethmoidal air cells:

• The posterior group (sometimes the posterior ethmoid sinus) drains into the superior meatus above the middle nasal concha; sometimes one or more opens into the sphenoidal sinus.

• The middle group (sometimes the middle ethmoid sinus) drains into the middle meatus of the nose on or above the bulla ethmoidalis.

• The anterior group (sometimes the anterior ethmoid sinus) drains into the middle meatus of the nose by way of the infundibulum.

Innervation

The ethmoidal air cells receive sensory fibers from the anterior and posterior ethmoidal nerves, and the orbital branches of the pterygopalatine ganglion, which carry the postganglionic parasympathetic nerve fibers for mucous secretion from the facial nerve.

Haller cell

Haller cells are infraorbital ethmoid air cells. These may arise from the anterior or posterior ethmoids.

Additional images

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  Ethmoidal cells

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  Ethmoid bone from the right side.

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  Left orbicularis oculi, seen from behind.

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  Lateral wall of nasal cavity; the three nasal conchæ have been removed.

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  Paranasal sinuses

External links

• SUNY Figs 33:04-07
• SUNY Labs 33:st-0711

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.