An atlas of skiagrams : illustrating the development of the teeth with explanatory text / by Johnson Symington and J. C. Rankin.

  • Johnson Symington
Date:
1908
Catalogue details

Licence: In copyright

Credit: An atlas of skiagrams : illustrating the development of the teeth with explanatory text / by Johnson Symington and J. C. Rankin. Source: Wellcome Collection.

    30/68 (page 14)
    Fig. i.-—Right Side of Male Infant fifteen months old and 28 inches high. This skiagram was taken after the skull had been cleaned, but not macerated, and then dried, so that the gum is shrunken. The incisors and first molars have erupted, but the temporary canine and second molars are still covered by the gum, although from the skiagram it might be supposed that these teeth had also erupted. The first milk molars have now distinct roots, which, however, have thin walls and large openings at their apices. The second milk molars are still destitute of roots. The permanent teeth calcified are the incisors, canines, and first molars. The large upper central incisor is seen through the roots of the two upper milk incisors; the lateral incisor lies internal to the milk canine, but is not distinctly marked on the skiagram. The upper canine is above and behind the root of the milk canine, and its crypt already extends to a higher level than those of the other teeth. The lower lateral incisor is interna] to the milk canine, while the canine is deeper and lies below and between the milk canine and first molar. Fig. 2.- Right Side of Female Infant two years old and 30 inches high. All the milk teeth have erupted except the second upper molar and the two posterior cusps of the second lower molar. The roots of the second milk molars are now forming, but only the crowns of the first permanent molars are calcified. Fig. A is from a dissection of this specimen. The maxilla and neighbouring bones were separated from the rest of the skull and part of the lachrymal, the os planum of the ethmoid, a small part of the sphenoid, and the bony roof of the maxillary sinus removed to expose from the lateral aspect the mueo-periosteal lining of the accessory sinuses of the nose. The drawing is the natnral size, and the specimen is viewed directly from the lateral aspect, and not, as in the skia- Fig. A. I*! t.t gram, partly from the front. The maxillary sinus measures 25 cm. in a sagittal direction, 1 cm. ver- tically, and 7 mm. from within out- wards, so that its main extent is in an antero-posterior direction. It reaches 7 mm. in front and 17 mm. behind its aperture of communication with the nose, and anteriorly lies on the outer side of the nasal duct. The lateral extension of the sinus has proceeded as far as the inner border of the infra- orbital canal. The only tooth that comes into close relation with the sinus at this age is the first permanent molar, the socket of which forms an elevation on the posterior and outer part of its floor, and is covered on the inner third of its upper surface by the sinus. [In the lettering on this figure, for ‘ 4th ’ frontal cell read ‘ 3rd,’ for ‘ 3rd ’ frontal cell read ‘ 1st,’ and for ‘ 1st ’ frontal cell read ‘ 4th.’]