In adult human subjects, the correlations were determined between the cross-sectional areas of the jaw muscles (measured in CT scans) and a number of facial angles and dimensions (measured from lateral radiographs). Multivariate statistical analysis of the skeletal variables in a group of 50 subjects led to the recognition of six independent factors determining facial shape, i.e., cranial base length, lower facial height, cranial base flexure and prognathism, facial width, mandibular length, and upper facial height. In 29 of these subjects, the cross-sectional areas of the jaw muscles were determined, and correlations between these areas and the scores on the above-mentioned factors were calculated. It appeared that the cross-sectional areas of temporalis and masseter muscles correlated positively with facial width, whereas the areas of masseter and both pterygoid muscles did so with mandibular length. It has been shown experimentally that a decrease in jaw muscle size in various animals likewise has an effect on facial width and mandibular length. Our results therefore support the hypothesis that in man too the jaw muscles affect facial growth and partly determine the final facial dimensions. They also hint that the role of each muscle is different.

Correlations between the cross-sectional area of the jaw muscles and craniofacial size and shape

Publisher Summary
This chapter presents a synthesis of recent advances made in bioarchaeology, an emerging discipline that emphasizes the human biological component of the archaeological record. The chapter presents an examination of the impact of economy and behavior on skeletal and dental tissues. Skeletal and dental tissues are remarkably sensitive to the environment. Such factors as diet, disease, population size and mobility, physical exercise, and work leave indelible marks on these tissues. The chapter describes the means by which skeletal remains have been and can be used for understanding processes that underlie human behavior. It also explores the impact of different lifeways on the skeleton with reference to nonpathological and pathological changes in articular joints, bone form and function, and the nature of skeletal and dental changes in light of the use of the jaws and teeth in both masticatory and non-masticatory roles.

6 – Bioarchaeological Interpretations of Subsistence Economy and Behavior from Human Skeletal Remains

The aim of this study was to investigate how the thickness of the masseter muscle relates to the maxillofacial morphology, including the thickness of alveolar process in the mandibular incisor region, and the thickness of the mandibular symphysis. The subjects consisted of 80 adult male volunteers (mean age: 23 years 8 months). The relationship between masseter muscle thickness and the maxillofacial skeleton was investigated by measuring the former by ultrasonography and the latter by roentgenographic cephalometry. The data were initially analysed using a multiple regression analysis. Thereafter, correlation coefficients were obtained by a simple regression analysis. The following results were found: 1. The thickness of the masseter muscle (mean +/- SD) was 15.8 +/- 3.0 mm in the relaxed state and 16.7 +/- 2.7 mm at maximal clenching. 2. Masseter muscle thickness was negatively correlated with the mandibular plane angle. 3. Masseter muscle thickness was positively correlated with the mandibular ramus height (Cd-Go), and the thickness of the alveolar process and that of the mandibular symphysis. It is therefore suggested that masticatory function influences the morphology of the mandible.

Maxillofacial morphology and masseter muscle thickness in adults.

This study presents univariate narrow-sense heritability estimates for 33 common craniometric dimensions, calculated using the maximum likelihood variance components method on a skeletal sample of 298 pedigreed individuals from Hallstatt, Austria Quantitative genetic studies that use skeletal cranial measurements as a basis for inferring microevolutionary processes in human populations usually employ heritability estimates to represent the genetic variance of the population The heritabilities used are often problematic: most come from studies of living humans, and/or they were calculated using statistical techniques or assumptions violated by human groups Most bilateral breadth measures in the current study show low heritability estimates, while cranial length and height measures have heritability values ranging between 0102-0729 There appear to be differences between the heritabilities calculated from crania and those from anthropometric studies of living humans, suggesting that the use of the latter in quantitative genetic models of skeletal data may be inappropriate The univariate skeletal heritability estimates seem to group into distinct regions of the cranium, based on their relative values The most salient group of measurements is for the midfacial/orbital region, with a number of measures showing heritabilities less than 030 Several possible reasons behind this pattern are examined Given the fact that heritabilities calculated on one population should not be applied to others, suggestions are made for the use of the data presented

Maximum likelihood estimation of human craniometric heritabilities.

The protruding chin is an attribute that defines modern Homo sapiens to the exclusion of all other primates, including fossil hominids. The functional significance of the chin has been contemplated for most of the 20th century, but as yet no compelling functional argument for its evolution has withstood careful scrutiny. Consequently, the human chin is often cited as an example of a nonadaptive trait. Past attempts to explain the chin in a functional or mechanical context have failed, largely as a result of an incomplete understanding of in vivo masticatory biomechanics. When the morphology of the chin is considered in light of experimental data on mastication, its evolution can be interpreted as a consequence of recent changes in mandibular proportions that have altered the relative importance of different masticatory stresses. Hypotheses proposing that chin morphology is the result of sexual selection or spatial constraints may be untestable. As with arguments that posit no functional role for the chin, the credibility of these hypotheses has depended, to a large degree, on the refutation of previous biomechanical explanations.

Functional morphology of the human chin

The prevalence of malocclusion is considered in three social classes categorized on the basis of income, in a North Indian population.

Epidemiological survey of occlusion in North India.

Facial height and breadth relative to dietary consistency and oral breathing in two populations (North India and U.S.).

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Morrow Ca

Author Tools

Chat about Author

Papers

Epidemiological survey of occlusion in North India.

Facial height and breadth relative to dietary consistency and oral breathing in two populations (North India and U.S.).