Cephalic index
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Cephalic index is the ratio of the maximum width of the head to its maximum length (i.e., in the horizontal plane, or front to back), sometimes multiplied by 100 for convenience. It is no longer used in adults, except for describing individuals' appearances, and has no correlation with behavior. It is still sometimes used for estimating the age of fetuses for legal and obstetrical reasons, in which case the differences in skull shapes between different populations are still of interest. Such an index is also used for animals, such as dogs and cats.
[edit] History
The cephalic index was defined by Swedish professor of anatomy Anders Retzius (1796-1860) and first used in physical anthropology to classify ancient human remains found in Europe.
It has been generally discredited since a study by Franz Boas at the turn of the 19th/20th century, and it became accepted in anthropology that the cephalic index was a purely environmental component. (However, Boas did not himself claim it was totally plastic).
[edit] Indices
Cephalic indices are grouped as in the following table:
| Females | Males | Scientific term | Meaning | Alternative term |
|---|---|---|---|---|
| < 75% | < 65% | dolichocephalic | 'long-headed' | mesocranial |
| 75% to 80% | 65% to 75% | mesocephalic | 'medium-headed' | mesaticephalic |
| > 80% | > 75% (male) | brachycephalic | 'short-headed' | brachycranial |
Technically, the measured factors are defined as the maximum width of the bones that surround the head, above the supramastoid crest (behind the cheekbones), and the maximum length from the most easily noticed part of the glabella (between the eyebrows) to the most easily noticed point on the back part of the head.
[edit] Brachycephalic animals
A brachycephalic skull is relatively broad and short (typically with the breadth at least 80% of the length).
Brachycephalic (snub-nosed) dogs and cats are very sensitive to high temperatures, making the choice of a sleep or travel crate surface especially important.
List of brachycephalic (snub-nosed) dogs:
- Boston Terrier
- Boxer
- Brussels Griffon
- Bull Terrier
- Dutch Pug
- English Bulldog
- English Toy Spaniel
- French Bulldog
- Japanese Spaniel (Japanese Chin)
- Japanese Pug
- Pekingese
- Shih Tzu
- Shar-Pei
List of brachycephalic (snub-nosed) cats:
[edit] Mesocephalic animals
A mesocephalic skull is of intermediate length and width. Mesocephalic skulls are not markedly brachycephalic or dolichocephalic.
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[edit] Dolichocephalic animals
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A dolichocephalic skull is relatively long skull (typically with the breadth less than 80% or 75% of the length).
List of dolicocephalic canines:
- Wolf
- Coyote
- Sighthounds such as
