Here are three papers that people here might be interested in:
Morphological analysis of the hindlimb in apes and humans. I. Muscle architecture
Abstract
We present quantitative data on the hindlimb musculature of Pan paniscus,Gorilla gorilla gorilla, Gorilla gorilla graueri ,Pongo pygmaeus abelii and Hylobates lar and discuss the findings in relation to the locomotor habits of each. Muscle mass and fascicle length data were obtained for all major hindlimb muscles. Physiological crosssectional area (PCSA) was estimated. Data were normalized assuming geometric similarity to allow for comparison of animals of different size/species. Muscle mass scaled closely to (body mass) 1.0 and fascicle length scaled closely to (body mass) 0.3 in most species. However, human hindlimb muscles were heavy and had short fascicles per unit body mass when compared with non-human apes. Gibbon hindlimb anatomy shared some features with human hindlimbs that were not observed in the non-human great apes: limb circumferences tapered from proximal-to-distal, fascicle lengths were short per unit body mass and tendons were relatively long. Non-human great ape hindlimb muscles were, by contrast, characterized by long fascicles arranged in parallel, with little/no tendon of insertion. Such an arrangement of muscle architecture would be useful for locomotion in a three dimensionally complex arboreal environment.
link (PDF) - free download courtesy of
Kristiaan D'AoûtMorphological analysis of the hindlimb in apes and humans. II. Moment arms
Abstract
Flexion/extension moment arms were obtained for the major muscles crossing the hip, knee and ankle joints in the orang-utan, gibbon, gorilla (Eastern and Western lowland) and bonobo . Moment arms varied with joint motion and were generally longer in proximal limb muscles than distal limb muscles. The shape of the moment arm curves (i.e. the plots of moment arm against joint angle) differed in different hindlimb muscles and in the same muscle in different subjects (both in the same and in different ape species). Most moment arms increased with increasing joint flexion, a finding which may be understood in the context of the employment of flexed postures by most nonhuman apes (except orang-utans) during both terrestrial and arboreal locomotion. When compared with humans, non-human great apes tended to have muscles better designed for moving the joints through large ranges. This was particularly true of the pedal digital flexors in orang-utans. In gibbons, the only lesser ape studied here, many of the moment arms measured were relatively short compared with those of great apes. This study was performed on a small sample of apes and thus differences noted here warrant further investigation in larger populations.
link (PDF) - free download courtesy of
Kristiaan D'AoûtThe human gluteus maximus and its role in running
Abstract
The human gluteus maximus is a distinctive muscle in terms of size, anatomy and function compared to apes and other non-human primates. Here we employ electromyographic and kinematic analyses of human subjects to test the hypothesis that the human gluteus maximus plays a more important role in running than walking. The results indicate that the gluteus maximus is mostly quiescent with low levels of activity during level and uphill walking, but increases substantially in activity and alters its timing with respect to speed during running. The major functions of the gluteus maximus during running are to control flexion of the trunk on the stanceside and to decelerate the swing leg; contractions of the stance-side gluteus maximus may also help to control flexion of the hip and to extend the thigh. Evidence for when the gluteus maximus became enlarged in human evolution is equivocal, but the muscle’s minimal functional role during walking supports the hypothesis that enlargement of the gluteus maximus was likely important in the evolution of hominid running capabilities.
link (PDF) - free download courtesy of
Harvard University Skeletal biology labsee also: Endurance running and the Evolution of Homo.
Nature. 432: 345-352. Free PDF
