| ethmoid bone | An irregularly shaped bone lying between the orbital plates of the frontal and anterior to the sphenoid bone; it consists of two lateral masses of thin plates enclosing air cells, attached above to a perforated horizontal lamina, the cribriform plate, from which descends a median vertical or perpendicular plate in the interval between the two lateral masses; the bone articulates with the sphenoid, frontal, maxillary, lacrimal, and palatine bones, the inferior nasal concha, and the vomer; it enters into the formation of the anterior cranial fossa, the orbits, and the nasal cavity. Synonym: os ethmoidale. (05 Mar 2000) |
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| ethmoid infundibulum | A passage from the middle meatus of the nose communicating with the anterior ethmoidal cells and frontal sinus. Synonym: infundibulum ethmoidale, ethmoid infundibulum. (05 Mar 2000) |
| ethmoid sinus | Numerous small thin-walled spaces or air cells in the ethmoid bone, where they form an ethmoidal labyrinth. (12 Dec 1998) |
| ethmoid sinusitis | Inflammation of the ethmoid sinus. It may present itself as an acute (associated with viral rhinitis) or chronic (associated with allergic or hyperplastic sinusitis) condition. (12 Dec 1998) |
| uncinate process of ethmoid bone | A sickle-shaped process of bone on the medial wall of the ethmoidal labyrinth below the middle concha; it articulates with the ethmoidal process of the inferior concha and partly closes the orifice of the maxillary sinus. Synonym: processus uncinatus ossis ethmoidalis. (05 Mar 2000) |
| lateral mass of ethmoid bone | A mass of air cells with thin bony walls forming part of the lateral wall of the nasal cavity; the cells are arranged in three groups, anterior, middle, and posterior, and are closed laterally by the orbital plate which forms part of the wall of the orbit. Synonym: labyrinthus ethmoidalis, ectethmoid, ectoethmoid, lateral mass of ethmoid bone. (05 Mar 2000) |