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The ethmoid bone (/ ˈ ɛ θ m ɔɪ d /; [1] [2] from Ancient Greek: ἡθμός, romanized: hēthmós, lit. 'sieve') is an unpaired bone in the skull that separates the nasal cavity from the brain. It is located at the roof of the nose, between the two orbits. The cubical bone is lightweight due to a spongy construction.
In mammalian anatomy, the cribriform plate (Latin for lit. sieve-shaped), horizontal lamina or lamina cribrosa is part of the ethmoid bone.It is received into the ethmoidal notch of the frontal bone and roofs in the nasal cavities.
The crista galli (Latin: "crest of the rooster") is a wedge-shaped, vertical, midline upward continuation of the perpendicular plate of the ethmoid bone of the skull, [1] projecting above the cribriform plate [2] into the cranial cavity. It serves as an attachment for the membranes surrounding the brain.
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; the lateral plate forms part of the orbit, the medial plate forms part of the nasal cavity.
The ethmoid air cells consist of numerous thin-walled cavities in the ethmoidal labyrinth [4] that represent invaginations of the mucous membrane of the nasal wall into the ethmoid bone. [3] They are situated between the superior parts of the nasal cavities and the orbits, and are separated from these cavities by thin bony lamellae. [4]
It is located in the midsagittal line, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones. The vomer forms the inferior part of the nasal septum in humans, with the superior part formed by the perpendicular plate of the ethmoid bone . [ 3 ]
Behind the lacrimal process of the inferior nasal conchae lies a broad, thin plate, the ethmoidal process, which ascends to join the uncinate process of the ethmoid; from its lower border a thin lamina, the maxillary process, curves downward and lateralward; it articulates with the maxilla and forms a part of the medial wall of the maxillary sinus.
The perpendicular plate of the ethmoid bone (vertical plate) is a thin, flattened lamina, polygonal in form, which descends from the under surface of the cribriform plate, and assists in forming the septum of the nose; it is generally deflected a little to one or other side. The anterior border articulates with the spine of the frontal bone and ...