Dimensions of forelimb muscles in orangutans and chimpanzees

摘要: Eight forelimbs of three orangutans and four chimpanzees were dissected the muscle mass, fascicle length physiological cross-sectional area (PCSA) all forelimb muscles systematically recorded to explore possible interspecies variation in dimensions. Muscle mass PCSA divided by total entire for normalization. The results indicate that ratios monoarticular elbow flexors (M. brachialis M. brachioradialis) are significantly larger orangutans. In contrast, biarticular upper arm (the short head M. biceps brachii long M. triceps brachii) chimpanzees. For rotator cuff muscles, force-generating capacity M. subscapularis is orangutans, whereas opposite muscle, M. infraspinatus, These differences dimensions two species may reflect functional specialization their different positional locomotor behaviors.