The ethmoid sinuses or ethmoid air cells of the
ethmoid bone are one of the four paired
paranasal sinuses. The cells are variable in both size and number in the
lateral mass of each of the ethmoid bones and cannot be palpated during an extraoral examination. They are divided into anterior and posterior groups.
The ethmoid air cells are numerous thin-walled cavities situated in the
ethmoidal labyrinth and completed by the
frontal,
maxilla,
lacrimal,
sphenoidal, and
palatine bone
In anatomy, the palatine bones () are two irregular bones of the facial skeleton in many animal species, located above the uvula in the throat. Together with the maxillae, they comprise the hard palate. (''Palate'' is derived from the Latin ''pa ...
s. They lie between the upper parts of the
nasal cavities and the
orbits, and are separated from these cavities by thin bony lamellae.
Groups of sinuses
The groups of the ethmoidal air cells drain into the nasal meatuses.
[Otorhinolaryngology, Head and Neck Surgery, Anniko, Springer, 2010, page 188]
* The posterior group the ''posterior ethmoidal sinus'' drains into the
superior meatus above the
middle nasal concha
The medial surface of the labyrinth of ethmoid consists of a thin lamella, which descends from the under surface of the cribriform plate, and ends below in a free, convoluted margin, the middle nasal concha (middle nasal turbinate).
It is rough, a ...
; sometimes one or more opens into the
sphenoidal sinus.
* The anterior group the ''anterior ethmoidal sinus'' drains into the
middle meatus of the
nose by way of the
infundibulum.
The two groups are divided by the basal lamella. This is one of the bony divisions of the ethmoid bone and is mostly contained inside the
ethmoid labyrinth
The ethmoidal labyrinth or lateral mass of the ethmoid bone consists of a number of thin-walled cellular cavities, the ethmoid air cells, arranged in three groups, anterior, middle, and posterior, and interposed between two vertical plates of bone ...
. Medially the lamella becomes the bony part of the middle concha.
Development
The ethmoidal cells (sinuses) and maxillary sinuses are present at birth.
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
The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of t ...
nerve fibers for
mucous
Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is ...
secretion 440px
Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical ...
from the
facial nerve.
Haller cell
Haller cells are infraorbital ethmoidal air cells lateral to the
lamina papyracea. These may arise from the anterior or posterior ethmoidal sinuses.
Pathology
Acute ethmoiditis in childhood and ethmoidal carcinoma may spread superiorly causing meningitis and cerebrospinal fluid leakage or it may spread laterally into the orbit causing
proptosis and
diplopia.
[Human Anatomy, Jacobs, Elsevier, 2008, page 210]
Additional images
File:Slide2ROMA.JPG, Ethmoid sinus. Ethmoidal air cells.Deep dissection. Superior view.
File:Diagram showing ethmoid sinus cancer that has spread to the lymph nodes CRUK 121.svg, Ethmoid sinus cancer that has spread to the lymph nodes
References
External links
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Bones of the head and neck