premaxilla


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premaxilla

[¦prē·mak′sil·ə]
(anatomy)
Either of two bones of the upper jaw of vertebrates located in front of and between the maxillae.
References in periodicals archive ?
6 in SL; dorsal fin slightly anterior to midbody; predorsal series of scales regular for 3-4 scales just before dorsal fin, irregular rows on the anterior two-thirds, not covering the median line; trunk scales 7418)36/5'; anal fin iv,26; sexual hooks numerous; large suborbital not developed, separated from the preopercillnr canal; premaxilla with 5-6 tricuspid outer teeth and 5 pentacuspid inner ones; maxilla relatively short, reaching to vertical through anterior margin of eye, with one small tooth; mandible with 5 strong, anterior teeth followed by much smaller ones; upper profile rather pointed, lower lip developed into a flap owing to probable lack of oxygen; humeral spot almost round, not clearly horizontally oval as in "typical" A.
In both cases the premaxilla was ranked the best predictor bone, followed by the maxilla, the opercle, the dentary, the cleithrum, and finally dentary body length.
The modified first haemal arch and anterior curvature of the ventral tip of the premaxilla warrant further investigation.
Upper jaw with outer row of curved, spaced, enlarged canines, decreasing in size posteriorly to distal tip of premaxilla, a band of several irregular rows of small conical teeth at symphysis, number of rows decreasing posterolaterally and ending just posterior to bend of dentary, innermost row slightly larger and directed posteriorly at symphysis, decreasing in size and becoming vertically oriented, and extending to distal tip of premaxilla.
Other characters are shared with other small cichlids, such as teeth present along the entire alveolar arm of the premaxilla, absence of tooth plates on ceratobranchial 4, absence of accessory lateral lines on caudal fin and infraorbitals reduced to three (the middle with terminal and a lateral opening).
9)% HL; teeth 5-10 on ocular-side premaxilla, 20-27 on blind-side premaxilla and 10-12 on ocular-side dentary, 23-29 on blindside dentary; gill rakers of first arch typically broad and robust, 6-11 total, 1-4 on upper arch, 5-7 on lower; gill rakers of second arch 6-11 total, 1 on upper and 5-10 on lower arch; dorsal orbit larger than eye length, orbit length 23.
According to Nemeth (1994), Champsodon vorax could be differentiated from all known species of gapers by the combination of the following characters: snout length almost equal to eye diameter; premaxilla notched lateral to symphysis; chin and breast scaled; triangular patch of scales between pectoral and pelvic fin bases extending ventroposteriorly as thick line toward vent, sometimes meeting scales on belly (Fig.
Villiform teeth in band on premaxilla and dentary; 2-3 (1-2) rows on vomer; 2-3 rows on palatine; none on ectopterygoid, endopterygoid or basihyal.
Teeth small, conical and recurved; premaxilla bearing a single row of teeth posteriorly, and 1-2 rows anteriorly, edentulous near symphysis; teeth on dentary in an irregular single row near symphysis continuing as a narrow band of 2-3 rows posteriorly; vomerine teeth larger than those on jaws, arranged in a large triangular patch; teeth on palatine arranged in a band of 2-3 rows; tongue with a band of 2-4 rows of densely-set teeth on glossohyal.