| Age | Circumference | Antero-post. diameter | Transverse diameter | Vertical diameter |
|---|---|---|---|---|
| 1 | 105 | 38 | 27 | 25 |
| 2 | 31 | 10 | 8 | 8 |
| 3 | 15 | 3 | 2 | 4 |
| 4 | 10 | 3 | 1 | 2 |
| 5 | 7 | 2 | 2 | 1 |
| 6 | 5 | 2 | 1 | 1 |
| 7 | 5 | 1 | 1 | 1 |
| 8 | 6 | 1 | 1 | 1 |
| 9 | 4 | 1 | 1 | 1 |
| 10 | 4 | 1 | 1 | 1 |
| 11 | 4 | 1 | 1 | 1 |
| 12 | 4 | 1 | 1 | 1 |
| 13 | 4 | 1 | 1 | 1 |
| 14 | 4 | 1 | 1 | 1 |
| 15 | 4 | 1 | 1 | 1 |
| 16 | 4 | 1 | 1 | 1 |
| 17 | 4 | 1 | 1 | 1 |
| 18 | 4 | 1 | 1 | 1 |
| 19 | 4 | 1 | 1 | 1 |
| 20 | 1 | 1 | 1 | 1 |
It appears from the above table that the total growth of the cranium takes place to a notable extent during the early years of life; as regards the diameters, the longitudinal diameter grows faster during the first few months than the transverse; but after the first year, the two maximum diameters which determine the cephalic index increase in very nearly the same proportion (constancy of the cephalic index throughout life). The vertical diameter on the contrary undergoes a relatively much greater increase than the two others, since, although much shorter than the transverse, it nevertheless overtakes and surpasses it in its absolute annual increase.
This corresponds to the fact that the first two diameters are indexes of growth relative to the base of the cranium, while the vertical diameter is the index of expansion of the cranial vault, which more directly follows the growth of the brain and elevates the forehead as it pushes upward.
Quétélet's figures, however, fail to show in the rhythm of growth that puberal acceleration which has been observed to take place in the growth of the brain. This contradicts the researches of Vitali and also those of Binet.
Similar studies have been made a number of times during the last few years, especially in America, but with English tables of measurement, and with little uniformity in the results obtained by the different investigators.
Among the most recent and most complete figures should be cited those of Bonnifay[38] in which however the measurement of the vertical diameter is lacking, or in other words the third element needed, in conjunction with the dimensions of length and breadth, to give the volumetric factors.
CRANIAL MEASUREMENTS AT DIFFERENT AGES
(According to Bonnifay)
| Age from — to — | Absolute figures | Amount of Increase | ||||
|---|---|---|---|---|---|---|
| Circumference | Antero-posterior diameter | Transverse diameter | Circumference | Antero-posterior diameter | Transverse diameter | |
| Birth to 15 days | 343.9 | 116.3 | 93.4 | — | — | — |
| 15 days to 2 months | 368.7 | 126.3 | 99.1 | 24.8 | 10.0 | 5.7 |
| 3 months to 4 months | 388.8 | 132.7 | 106.0 | 20.1 | 6.4 | 6.9 |
| 6 months to 1 year | 429.8 | 145.4 | 118.2 | 41.0 | 12.7 | 12.2 |
| 1 year to 2 years | 459.7 | 154.3 | 129.3 | 29.9 | 8.9 | 11.1 |
| 2 years to 3 years | 473.5 | 161.9 | 133.3 | 13.8 | 7.6 | 4.0 |
| 3 years to 4 years | 487.4 | 166.2 | 136.3 | 13.9 | 4.3 | 3.0 |
| 4 years to 5 years | 495.7 | 169.9 | 138.3 | 8.3 | 3.7 | 2.0 |
| 5 years to 6 years | 497.8 | 171.9 | 140.4 | 2.1 | 2.0 | 2.1 |
| 6 years to 7 years | 504.4 | 172.8 | 141.1 | 6.6 | 0.9 | 0.7 |
| 7 years to 8 years | 511.6 | 175.2 | 143.7 | 7.2 | 2.4 | 2.6 |
| 8 years to 9 years | 514.1 | 176.1 | 144.3 | 2.5 | 0.9 | 0.6 |
| 9 years to 10 years | 514.7 | 176.4 | 144.2 | 0.6 | 0.3 | 0.9 |
| 10 years to 11 years | 519.8 | 177.1 | 146.6 | 5.1 | 0.7 | 2.3 |
| 11 years to 12 years | 521.1 | 177.5 | 145.7 | 1.3 | 0.4 | 0.1 |
| 12 years to 13 years | 529.7 | 180.1 | 147.8 | 8.6 | 2.6 | 1.2 |
| 13 years to 14 years | 533.1 | 178.1 | 148.5 | 3.4 | — | 0.7 |
| 14 years to 17 years | 548.8 | 182.4 | 152.2 | 15.7 | 2.3 | 3.7 |
| 22 years to 27 years | 549.1 | 186.6 | 153.2 | 0.3 | 4.2 | 1.0 |