Understanding What Are the Three Head Shapes: Brachycephalic, Mesocephalic, and Dolichocephalic

September 30, 2025 •

3 min read

First defined in the 19th century by Swedish professor Anders Retzius, the cephalic index is the primary metric used to classify head shapes into categories. This system, which relates head width to length, is the basis for explaining what are the three head shapes: dolichocephalic, mesocephalic, and brachycephalic. Though rooted in historical anthropology, it helps us understand the natural diversity of human cranial anatomy.

Quick Summary

The three primary head shapes—brachycephalic, mesocephalic, and dolichocephalic—are defined by the cephalic index, a ratio of head width to length. This measurement provides a scientific way to categorize cranial morphology and understand natural variations in human and animal anatomy.

Key Points

Three primary head shapes: Head shapes are anatomically classified as dolichocephalic (long and narrow), mesocephalic (medium), or brachycephalic (short and broad), based on cranial proportions.
The cephalic index is key: This classification is determined by the cephalic index, a ratio of the head's maximum width to its maximum length, expressed as a percentage.
Genetics and environment influence shape: Head shape is highly heritable, with certain genes playing a significant role, though environmental factors like infant positioning can also influence cranial development.
Head shape is not face shape: The anatomical classification of head shape differs from aesthetic face shapes (like oval, square, or heart) which are used for styling and cosmetic purposes.
Health may be a factor in extreme cases: While most head shape variation is normal, conditions like craniosynostosis involving premature skull fusion can require medical intervention. Orthodontists also consider head shape in treatment.
Historical roots in anthropology: The cephalic index was developed in the 19th century and has evolved from a tool for racial classification to a more nuanced metric for studying human variation.

The Science of Head Shape: The Cephalic Index

Classifying head shape relies on the cephalic index, a measurement developed to describe skull proportions. It is calculated as the ratio of maximum head width to maximum head length, expressed as a percentage. The formula is:

$$CI = \frac{\text{Maximum Head Width}}{\text{Maximum Head Length}} \times 100$$

Measuring requires calipers or a flexible tape to find the widest points (eurion) and the length from the forehead (glabella) to the back of the skull (opisthocranion). The resulting percentage places a head into one of the three main categories, representing a range of cranial variation. Originally used in anthropology to categorize populations, today the index is primarily used to understand natural human variation.

A Closer Look at the Three Head Shapes

Head shapes are categorized as Dolichocephalic (long-headed), Brachycephalic (short-headed), or Mesocephalic (medium-headed) based on the cephalic index. Dolichocephalic heads have an index typically less than 75%, appearing longer front-to-back than side-to-side. Examples include Greyhounds. Brachycephalic heads typically have an index greater than 80%, appearing wider than long, with Pugs and Bulldogs being examples. Mesocephalic heads have an index between 75% and 80%, indicating balanced proportions, common in many human populations and breeds like Beagles. These categories reflect natural skull structure variations.

Head Shape vs. Face Shape: What's the Difference?

Head shape, based on the cephalic index, is an anatomical classification of the skull's proportions. Face shape, on the other hand, refers to the visual outline of facial features and is used for cosmetic purposes like choosing hairstyles. Face shape is assessed visually and includes types like oval, round, square, or heart, which don't directly correspond to the cephalic index. An individual with a mesocephalic skull can have various face shapes.

The Influence of Genetics and Environment

Head shape is largely inherited, with specific genes like RUNX2 influencing skull development. However, environmental factors also play a role, especially in infancy when the skull is soft. Consistent pressure, such as from sleeping position, can lead to temporary molding like positional plagiocephaly or brachycephaly. Factors like climate, nutrition, and lifestyle can also influence average head shapes in populations over generations.

Health Implications and Orthodontic Relevance

Most head shape variations are normal, but some abnormal shapes can be clinically significant. Craniosynostosis, a premature fusion of skull sutures, can cause severe deformities requiring surgery. Orthodontists consider a patient's head and facial type (dolichocephalic, mesocephalic, or brachycephalic) in treatment planning because it affects jaw growth and bite. This helps determine the best approach for aligning teeth and jaw structures.

Comparison of Head Shapes


Feature	Dolichocephalic	Mesocephalic	Brachycephalic
Cephalic Index	< 75%	75% - 80%	> 80%
Length-to-Width Ratio	Head is significantly longer than it is wide	Head has balanced, intermediate length and width	Head is significantly wider than it is long
Common Appearance	Long and narrow	Moderately proportioned	Short and broad, often with a flatter back
Orthodontic Features	Can be associated with long, narrow jaws and potential crowding	Often fewer orthodontic issues due to balanced proportions	Can be associated with wide jaws and sometimes dental crowding

Conclusion

The three primary head shapes—brachycephalic, mesocephalic, and dolichocephalic—describe the natural range of human cranial anatomy based on the cephalic index. This measurement provides a clear method for classifying skull proportions. Both genetics and environmental factors contribute to these variations, particularly in early development. It's important to distinguish between head shape (anatomical) and face shape (visual/cosmetic). While most head shapes are normal, extreme variations or conditions like craniosynostosis have clinical significance, and orthodontists consider head shape in treatment. For further information on cranial development and related health issues, resources like {Link: National Institutes of Health https://fiveable.me/key-terms/anatomy-physiology/cephalic-index} can provide deeper insights.

Frequently Asked Questions

To calculate your cephalic index, you divide the maximum width of your head by its maximum length and multiply by 100. The width is typically measured across the widest part of the sides, and the length from the forehead to the back of the skull.

Head shape refers to the anatomical classification of the entire skull's proportions, such as dolichocephalic or brachycephalic, based on the cephalic index. Face shape, like oval or square, refers to the visual outline of your facial features for aesthetic purposes like choosing hairstyles.

Yes, head shape is highly heritable, and studies have identified several genes that influence cranial development. Genetics are considered the primary determinant, though environmental factors can also play a role.

Significant changes in head shape after early childhood are rare, as the skull bones fuse. However, environmental factors like infant sleeping position can cause temporary molding, and extreme medical conditions like craniosynostosis involve abnormal fusion that alters shape.

In most cases, head shape is a normal variation with no health concerns. However, certain medical conditions like craniosynostosis cause abnormal skull development with serious health risks. In some animals, like brachycephalic dogs, extreme shapes can lead to specific health issues.

Using dog breeds as clear examples, Dolichocephalic breeds include Greyhounds, Mesocephalic breeds include Beagles, and Brachycephalic breeds include Pugs and Bulldogs.

Plagiocephaly is a condition where a baby's head has a flattened spot on one side. It can be caused by the pliable skull being subjected to consistent external pressure, such as sleeping in the same position.