Electromyography of brachial muscles in Pan troglodytes and Pongo pygmaeus
Article first published online: 27 APR 2005
Copyright © 1983 Wiley-Liss, Inc., A Wiley Company
American Journal of Physical Anthropology
Volume 61, Issue 1, pages 75–83, May 1983
How to Cite
Tuttle, R. H., Velte, M. J. and Basmajian, J. V. (1983), Electromyography of brachial muscles in Pan troglodytes and Pongo pygmaeus. Am. J. Phys. Anthropol., 61: 75–83. doi: 10.1002/ajpa.1330610108
- Issue published online: 27 APR 2005
- Article first published online: 27 APR 2005
- Manuscript Accepted: 15 DEC 1982
- Manuscript Received: 8 OCT 1982
- Arm muscles;
- Suspensory behavior
Electromyographic recordings were taken from all heads of the triceps brachii and biceps brachii muscles and from the anconeus, brachialis, and brachioradialis muscles in a chimpanzee and an orangutan as they stood still and walked quadrupedally on horizontal and inclined surfaces, engaged in suspensory behavior, reached overhead, and manipulated a variety of foods and artifacts.
Like the gorilla (Tuttle and Basmajian, 1974a), the chimpanzee and orangutan possess special close-packed positioning mechanisms that allow the bulky muscles that cross their elbow joints to remain silent during quiet pendant suspension.
We found no major myological features that would dramatically separate the arms of knuckle-walking African apes from those of the orangutan. With a few exceptions, which could as well be attributed to individual variation as to interspecific differences, the brachial muscles acted similarly during quadrupedal positional behaviors, irrespective of whether the hands of the subjects were knuckled (African apes), fisted (chimpanzee and orangutan), or placed in modified palmigrade postures (orangutan).
Evolutionary transformations, from brachial and elbow complexes like those of Pongo to ones like Pan, or vice versa, would probably be achieved quite readily as the species changed its substrate preferences and positional habits.