A person's head length and width increase from birth to late adolescence, when the adult dimensions are reached. The cephalic index is a ratio of the head width divided by the length.
Measurement:
(1) Use calipers.
(2) Head length = maximal diameter through the sagittal plane, using the glabella in front and the opisthocranion in back as landmarks.
(3) Head width = maximal biparietal diameter.
(4) Skull deformities or excessive hair may interfere with accurate measurements.
Head Length
The following equations were derived to approximate the data of Feingold and Bossert as shown in Figure 7.6, page 105, Hall et al (1995).
mean head length in cm for ages 1 to 3 =
= (0.1867 * ((age in years)^3)) - (1.5 * ((age in years)^2)) + (4.363 * (age in years)) + 12.95
mean head length in cm for ages 3-16 =
= (0.000266 * ((age in years)^3)) - (0.0156 * ((age in years)^2)) + (0.31322* (age in years)) + 16.773
mean head width in cm for ages 16+ =
= 17.67 cm
-2 SD head length in cm for ages 1 to 3 =
= (0.15 * ((age in years)^3)) - (1.445 * ((age in years)^2)) + (4.875 * (age in years)) + 10.5
-2 SD head length in cm for ages 3-16 =
= (0.000298 * ((age in years)^3)) - (0.0163 * ((age in years)^2)) + (0.33186 * (age in years)) + 15.313
-2 SD head length in cm for ages 16+ =
= 18.88 cm
+2 SD head length in cm for ages 1 to 3 =
= (-0.02 * ((age in years)^3)) - (0.11 * ((age in years)^2)) + (1.22 * (age in years)) + 16.7
+2 SD head length in cm for ages 3-12 =
= (0.00106 * ((age in years)^3)) - (0.0374 * ((age in years)^2)) + (0.4891 * (age in years)) + 17.6897
+2 SD head length in cm for ages 12+ =
= 20 cm
Head Width
The following equations were derived to approximate the data of Feingold and Bossert as shown in Figure 7.9, page 108, Hall et al (1995)
mean head width in cm for ages 1 to 3 =
= - (0.3 * ((age in years)^2)) + (1.829 * (age in years)) + 10.307
mean head width in cm for ages 3-16 =
= - (0.0052 * ((age in years)^2)) + (0.192 * (age in years)) + 12.586
mean head width in cm for ages 16+ =
= 14.33 cm
-2 SD head width in cm for ages 1 to 3 =
= - (0.32 * ((age in years)^2)) + (1.96 * (age in years)) + 9.19
-2 SD head width in cm for ages 3-16 =
= - (0.00488 * ((age in years)^2)) + (0.1689 * (age in years)) + 11.717
-2 SD head width in cm for ages 16+ =
= 13.16 cm
+2 SD head width in cm for ages 1 to 3 =
= - (0.2645 * ((age in years)^2)) + (1.665 * (age in years)) + 11.374
+2 SD head width in cm for ages 3-16 =
= - (0.004712 * ((age in years)^2)) + (0.21159 * (age in years)) + 13.427
+2 SD head width in cm for ages 16+ =
= 15.63 cm
Cephalic Index
cephalic index =
= (head width) * 100 / (head length)
|
Cephalic Index |
Interpretation |
|
< 76 |
dolichocephaly |
|
76 - 80.9 |
normal |
|
>= 81 |
brachycephaly |
