. Quain's elements of anatomy . e subjoined table. Thecorresponding teeth of the upper jaw appear somewhat later. Molar, first 6 years. Incisors, central . . . . 7 „ „ lateral ....... 8 ,, Bicuspids, anterior 9 „ ,, posterior 10 „ Caniaes . , . . . 11 to 12 „ Molars, second . 12 to 13 „ „ third (or wisdom) 17 to 25 „ It is just before the shedding of the temporaiy incisors—, about the sixthyear, that there is the greatest number of teeth in the jaws. At that periodthere are all the milk-teeth, and the crowns of aU the permanent set except thewisdom-teeth, making forty-eight (see fig. 489).
. Quain's elements of anatomy . e subjoined table. Thecorresponding teeth of the upper jaw appear somewhat later. Molar, first 6 years. Incisors, central . . . . 7 „ „ lateral ....... 8 ,, Bicuspids, anterior 9 „ ,, posterior 10 „ Caniaes . , . . . 11 to 12 „ Molars, second . 12 to 13 „ „ third (or wisdom) 17 to 25 „ It is just before the shedding of the temporaiy incisors—, about the sixthyear, that there is the greatest number of teeth in the jaws. At that periodthere are all the milk-teeth, and the crowns of aU the permanent set except thewisdom-teeth, making forty-eight (see fig. 489). During the growth of the teeth the jaw increases in depth and length, andundergoes changes in form. In the child it is shallow, but it becomes muchdeeper in the adult. In the young subject the alveolar arch describes almost thesegment of a circle ; but in the adult the cuiwe is semi-elliptical. The increasewhich takes place in the length of the jaw arises from a growth behind the posi- Fig. Fig. 489.—The tekth op a child of six teaks, ■with the calcified pakts of thePERMANENT TEETH EXPOSED (after Heule and modified from nature, A. T.). The whole of the teetb. of the right side are shown, together with the three front teethof the left side : in the upper and lower jaws the teeth are indicated as follows, viz. :—1, milk-teeth—i, inner or first incisor ; i\ outer or second incisor; c, canine ; in, firstmolar; in, second molar. 2,2}ermanent4eeth—I, inner or first incisor; I, outer orsecond incisor ; C, canine ; B, first bicuspid ; B, second bicuspid ; M, the first molar,which has passed through the gums; M, the second molar, which has not yet risen abovethe gums : the third molar is not yet formed. 0 0 2 564 THE TEETH. t:on of the milk-teeth, so as to provide room for the three additional teeth oneach side belonging to the permanent set. At certain periods in the growth ofthe jaws there is not sufficient room in the alveolar arch for the growing s
Size: 1677px × 1489px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1800, booksubjectanatomy, booksubjecthumananatomy
