## **Core Concept**
The cephalic index, also known as the cranial index, is a numerical value used in physical anthropology to categorize the skull shapes of different human populations. It is calculated as the ratio of the width of the head multiplied by 100 divided by its length (from front to back). The index helps classify human populations into different categories based on head shape.

## **Why the Correct Answer is Right**
A cephalic index of 80-85 falls into the category of **brachycephalic** or **short-headed** populations. Brachycephalic individuals have a broad, short skull. This classification is significant in anthropology and forensic science for identifying and studying human populations.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because a cephalic index of 80-85 does not correspond to the dolichocephalic (long-headed) category, which typically has an index below 75.
- **Option B:** This option is incorrect because a cephalic index of 80-85 does not correspond to the mesaticephalic (medium-headed) category, which usually has an index ranging approximately from 75 to 79.9.
- **Option D:** This option is incorrect because a cephalic index of 80-85 specifically does not match the dolichocephalic category.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the cephalic index is used to classify skull shapes into three main categories:
- **Dolichocephalic** (long-headed): Index < 75 - **Mesocephalic** (medium-headed): Index 75-79.9 - **Brachycephalic** (short-headed): Index ≥ 80 ## **Correct Answer:** .