Classification

Abstract

Heads vary greatly in shape and size. When these variations are extreme, they are regarded as deformities, and this judgement is based on intuitive concepts of normality. The unusual head is thought to be too long, too broad, too high, too large or small, or it is lopsided. These concepts vary in different societies and cultures. Objective measurements can be used to supplement aesthetic impressions, and the various craniometric indices devised by anthropologists to quantitate racial variations have some utility in defining deformities. The most relevant is the cephalic index (more strictly the horizontal cephalic index), defined as (maximum breadth/maximum length) × 100 and measured either directly (p. 77) or on skull radiographs (p. 81). It is a very useful measurement in clinical practice: it quantitates the visual impression of a long (dolichocephalic), broad (brachycephalic), or ‘normal’ (mesaticephalic) head, and it is a reliable measure of the success of reconstructive surgery. The vertical cephalic index has been defined as (maximum height/maximum length) × 100. This index ought to quantify the impression of a high (hypsicephalic) head but it is not very easily measured in small children, and we have so far made little use of it. Anthropological textbooks differ slightly in how they derive these indices: Fig. 9.1 and 9.2 give the dimensions used in our calculations.