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

Weijs, W.A.; Hillen, B.

doi:10.1002/ajpa.1330700403

Cited by 190 publications

(109 citation statements)

References 27 publications

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“…area (Weijs and Hillen, 1986;Hannam and Wood, 1989). Thus, assuming a linear relationship between the raw and the actual muscle PCSA, we generated a set of correction factors (CF MASS, i , CF MPT, i , CF TEMP, i ) for the i-th specimen (i ϭ 1, 2 where the "actual PCSAs" were taken from computed tomography studies of the human jaw muscles Hillen, 1985a, 1986).…”

Section: Estimation Of Model Inputsmentioning

confidence: 99%

Bite force production capability and efficiency in Neandertals and modern humans

O'Connor

Franciscus

Holton

2005

Am. J. Phys. Anthropol.

103

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Although there is consensus that Neandertal craniofacial morphology is unique in the genus Homo, debate continues regarding the precise anatomical basis for this uniqueness and the evolutionary mechanism that produced it. In recent years, biomechanical explanations have received the most attention. Some proponents of the "anterior dental loading hypothesis" (ADLH) maintain that Neandertal facial anatomy was an adaptive response to high-magnitude forces resulting from both masticatory and paramasticatory activity. However, while many have argued that Neandertal facial structure was well-adapted to dissipate heavy occlusal loads, few have considered, much less demonstrated, the ability of the Neandertal masticatory system to generate these presumably heavy loads. In fact, the Neandertal masticatory configuration has often been simultaneously interpreted as being disadvantageous for producing large bite forces. With rare exception, analyses that attempted to resolve this conflict were qualitative rather than quantitative. Using a three-dimensional digitizer, we recorded a sequence of points on the cranium and associated mandible of the Amud 1, La Chapelle-aux-Saints, and La Ferrassie 1 Neandertals, and a sample of early and recent modern humans (n = 29), including a subsample with heavy dental wear and documented paramasticatory behavior. From these points, we calculated measures of force-production capability (i.e., magnitudes of muscle force, bite force, and condylar reaction force), measures of force production efficiency (i.e., ratios of force magnitudes and muscle mechanical advantages), and a measure of overall size (i.e., the geometric mean of all linear craniofacial measurements taken). In contrast to the expectations set forth by the ADLH, the primary dichotomy in force-production capability was not between Neandertal and modern specimens, but rather between large (robust) and small (gracile) specimens overall. Our results further suggest that the masticatory system in the genus Homo scales such that a certain level of force-production efficiency is maintained across a considerable range of size and robusticity. Natural selection was probably not acting on Neandertal facial architecture in terms of peak bite force dissipation, but rather on large tooth size to better resist wear and abrasion from submaximal (but more frequent) biting and grinding forces. We conclude that masticatory biomechanical adaptation does not underlie variation in the facial skeleton of later Pleistocene Homo in general, and that continued exploration of alternative explanations for Neandertal facial architecture (e.g., climatic, respiratory, developmental, and/or stochastic mechanisms) seems warranted.

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Section: Estimation Of Model Inputsmentioning

confidence: 99%

Bite force production capability and efficiency in Neandertals and modern humans

O'Connor

Franciscus

Holton

2005

Am. J. Phys. Anthropol.

103

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“…The jaw-closing muscle activity is said to be the greatest in subjects with a large posterior facial height, a small anterior facial height, a long mandible, a flat mandibular plane, and a small gonial angle (Moller, 1966;Ingervell and Thilander, 1974;Tabe, 1976). Temporal and masseter cross-sectional areas are larger in subjects with larger facial widths, while masseter and pterygoid muscle cross-sections are greater when the mandibular length is larger (Weijs and Hillen, 1986). These relationships are independent of the over-all size, and their specificity argues for differences in the tension-generating capacities of muscles according to facial types.…”

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confidence: 90%

Morphological Characteristics of Vertical Sections of the Mandible Obtained by CT Scanning.

Kasai

Enomoto

Ogawa

et al. 1996

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“…In general it can be assumed that craniofacial width is linked with the crosssectional areas or thickness of the masticatory muscles [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Influence of Myofunctional Therapy on Upper Intercanine Distance

Moschik¹

2015

JDODT

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Objectives: The study was designed to investigate the correlation between myofunctional exercises, including repositioning of the tongue onto the palate and changes in intercanine distance of the upper jaw in non-growing patients. Methods:In this retrospective study a total of 141 women and men above the age of 18, treated by the Coulson Institute of Orofacial Myology, with no simultaneous orthodontic therapy, were included. All subjects have participated in a myofunctional therapy program for at least 8 months. The training consisted of various muscle exercises for the lips, cheeks, tongue and body posture and breathing. Additionally, the patients put a small dissolvable gelatine pad onto the palate three times a day to assist the swallowing function. Throughout therapy the length of the philtrum, intercanine distance and overjet were measured.Results: After 8 sessions the average intercanine distance increased by 3.2 mm, the philtrum elongated by 5.4 mm and the overjet decreased by 1.2 mm. Conclusion:The results indicate that tooth position can be changed by muscle therapy, even in non-growing subjects. This implies that muscle training can be a highly supportive therapy for orthodontic treatment.

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

Cited by 190 publications

References 27 publications

Bite force production capability and efficiency in Neandertals and modern humans

Bite force production capability and efficiency in Neandertals and modern humans

Morphological Characteristics of Vertical Sections of the Mandible Obtained by CT Scanning.

Influence of Myofunctional Therapy on Upper Intercanine Distance

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