The 84th Annual Meeting of the American Association of Physical Anthropologists (2015)

Functional constraints of primate feeding: Modeling the effect of ligaments and TMJ morphology


1Department of Oral Biology, University of Illinois at Chicago, 2Department of Anthropology, University of Arkansas, 3Department of Evolutionary Anthropology, Duke University, 4Department of Community and Family Medicine, Duke University, 5Department of Organismal Biology and Anatomy, University of Chicago

March 27, 2015 8:15, Grand Ballroom A/B Add to calendar

The movement of the mandible with respect to the cranium during feeding is the result of the interaction of active mechanisms (e.g., muscle activation patterns and muscle dynamics), and passive mechanisms (e.g., morphology of jaw joint, elastic and inertial properties of muscles, occlusal morphology). The relative importance of these passive mechanisms, however, is not clear and is often overlooked with respect to active mechanisms. In a previous study, we have shown that the axis of rotation of the mandible, a measure of jaw movement, changes through the gape cycle and the overall location of this axis varies among individuals and species, but it is consistent within an individual. In this study we explore the effect of ligaments and articular morphology on determining the movement of the mandible during feeding. We used 3D models of both cranium and mandible of three species of primates (Papio, Macaca, Cebus). The potential range of mandible positions were modeled by randomly rotating and translating the mandible with respect to the cranium. To constrain the model we used the length of mandibular ligaments (i.e., sphenomandibular, stylomandibular, and temporomandibular) as well as the posterior band of the TMJ, measured from dissections, as well as avoiding the 3D surfaces of the cranium and mandible to overlap. We found little evidence that ligaments drive mandible movement (with the exception of the extreme adduction or protrusion). In contrast, jaw joint and occlusal morphology have larger effects in determining mandible position during feeding.

Bcs 0962682, 0725147, 0531067, 0240865, 0101930