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3‐D range of motion envelopes reveal interacting degrees of freedom in avian hind limb joints
Author(s) -
Kambic Robert E.,
Roberts Thomas J.,
Gatesy Stephen M.
Publication year - 2017
Publication title -
journal of anatomy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 118
eISSN - 1469-7580
pISSN - 0021-8782
DOI - 10.1111/joa.12680
Subject(s) - degrees of freedom (physics and chemistry) , range of motion , rotation (mathematics) , joint (building) , extant taxon , hindlimb , anatomy , rotation around a fixed axis , maxima and minima , computer science , physics , mathematics , biology , artificial intelligence , classical mechanics , mathematical analysis , evolutionary biology , structural engineering , medicine , engineering , surgery , quantum mechanics
Measuring range of motion ( ROM ) is a valuable technique that can link bone morphology to joint function in both extant and extinct taxa. ROM results are commonly presented as tables or graphs of maxima and minima for each rotational degree of freedom. We investigate the interactions among three degrees of freedom using X‐ray reconstruction of moving morphology ( XROMM ) to measure ROM of the main hind limb joints of Helmeted Guineafowl ( Numida meleagris ). By plotting each rotation on an axis, we generate three‐dimensional ROM volumes or envelopes composed of hundreds of extreme joint positions for the hip, knee, and intertarsal joints. We find that the shapes of ROM volumes can be quite complex, and that the contribution of long‐axis rotation is often substantial. Plotting in vivo poses from individual birds executing different behaviors shows varying use of potential rotational combinations within their ROM envelopes. XROMM can provide unprecedented high‐resolution data on the spatial relationship of skeletal elements and thereby illuminate/elucidate the complex ways in which soft and hard tissues interact to produce functional joints. In joints with three rotational degrees of freedom, two‐dimensional representations of ROM (flexion/extension and abduction/adduction) are incomplete.