mesethmoid


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Related to mesethmoid: mesethmoid bone

mesethmoid

[me′zeth‚mȯid]
(anatomy)
A bone or cartilage in the center of the ethmoid region of the vertebrate skull; usually constitutes the greater portion of the nasal septum.
References in periodicals archive ?
2), and is supported by a single synapomorphy: anteroventral margin of prevomer situates well posteriorly to anteroventral margin of mesethmoid (32: 0 [right arrow] 1, only occurring independently in a few taxa outside this clade C38 and only reverted, inside of it, in cypriniforms; the condition of [dagger] Santanichthys diasii and of [dagger] Clupavus maroccanus is not clear).
Nasal cavity extending medially, separated from contralateral structure by thin ventromedian lamina of mesethmoid.
Frontal contacting mesethmoid but not lateral ethmoid.
Ethmomaxillary ligament originating on mesethmoid, inserting on maxilla dorsal process.
0 times in base of the cranium; preocular spines always present; supraocular and parietal spines small or absent; postocular, tympanic and nuchal spines entirely absent; cranial ridges absent except for the parietal which is very low and sometimes scaled over; parietals widely separated; mesethmoid processes depressed or slightly directed upward; base of cranium strongly curved; ventral process of basisphenoid feeble; nasal spines low, but strong.
pachycephalus: "Cranium very thick and heavy; interorbital space deeply concave, about 3 1/2 in base of cranium; cranial spines broad and stout, the pointed tips directed backward; preocular, postocular, tympanic and parietal spines present; supraocular, coronal and nuchal spines absent; supraocular ridges exceedingly high and stout, forming a narrow flat area between them; frontal ridges barely evident, can not be seen without elimination of the skin; parietal ridges broad and high, but a little lower than the supraocular ridges; nasal spines stout, directed upward and slightly backward; mesethmoid processes strongly compressed, directed forward and upward; parietal bones separated; base of cranium straight; ventral process of basisphenoid entirely meeting the parasphenoid.
3 times in base of the cranium; cranial spines well developed, directed straightly backward; preocular, postocular, tympanic and parietal spines always present supraocular, corneal and nuchal spines absent; parietal ridges high and naked; frontal ridges low but distinct, the space between them shallowly concave; supraocular edges low or depressed, as high as or lower than the frontal ridges; mesethmoid processes slightly elevated upward; base of cranium some-what curved; parietals separated or partly meeting; ventral process of the basisphenoid well developed, entirely meeting the parasphenoid.
Mesethmoid cartilage lacking extension to dorsal and lateral margins of rhinosphenoid, but with cartilage along dorsal and anterior margin of parasphenoid.
Mesethmoid cartilage extending to anterior limit of parasphenoid.
Anterolateral processes of mesethmoid (or of supraethmoid and/ or rostrodermethmoids) supporting and/or articulating with premaxillae.
fused with mesethmoid and/or prevomer) or not (in this case, this character would be inapplicable), there is a good amount of evidence suggesting that in the members of Anguilla and Conger the premaxillae are fused to the mesethmoid and prevomer and that these fishes do have premaxillary teeth (see e.