The frog: an introduction to anatomy, histology, and embryology . asals are two triangular bones on the dorsalsurface of the anterior end of the head : the basesof the triangles are turned towards the middleline and meet each other in front, while theirposterior ends diverge and enclose, with theanterior ends of the frontoparietals, a diamond-shaped patch in which the sphenethmoid is visibleon the dorsal surface of the The vomers are two triradiate bones on the ventralsurface of the fore part of the skull: each vomerbears in its inner and posterior angle a small 46 THE SKELETON OF TH
The frog: an introduction to anatomy, histology, and embryology . asals are two triangular bones on the dorsalsurface of the anterior end of the head : the basesof the triangles are turned towards the middleline and meet each other in front, while theirposterior ends diverge and enclose, with theanterior ends of the frontoparietals, a diamond-shaped patch in which the sphenethmoid is visibleon the dorsal surface of the The vomers are two triradiate bones on the ventralsurface of the fore part of the skull: each vomerbears in its inner and posterior angle a small 46 THE SKELETON OF THE FROG group of pointed teeth, and forms the innerboundary of the posterior narial opening of itsside. 3. The Jaws consist of two cartilaginous arches on each side,maxillary and mandibular, in connection with whichcartilage-bones and membrctne-hones are arch meets its fellow in the middle line in front;and the maxillary arches, forming the upper jaw, arefirmly connected with the cranium by anterior andposterior bony struts. a. The Maxillary Q H Fig. 9.—The frogs skull from the right , parasphenoid; AS, angulosplenial; B, anterior cornu of hyoid;C, columella; D, dentary; E, exoccipital; F, nostril; FP,^ fronto-parietal; H, body of hyoid; L, aperture for exit of optic nerve;M, maxilla ; MM, mentomeckelian; M, aperture for exit of fifth andseventh nerves^H, nasal; O, pro-otic ; p, pterygoid ; PM, premaxilla;Q, quadratojugal; R, aperture for exit of ninth and tenth nerves;S, squamosal; SE, sphenethmoid; T, posterior cornu of hyoid. i. The pterygoid* is a large triradiate bone, the innerlimb of which is connected with the auditorycapsule; while the posterior limb runs back tothe angle of the mouth, and the anterior limbforwards along the upper jaw to the palatinebone. ii. The palatine* is a slender transverse bone, con- • These, originally cartilage-bones, become more or less ensheathedby membrane-elements in the course of development. THE SKULL 47 ne
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbiology, bookyear1896
