Fig. 1. Schematic drawing of pectoralis, latissimus dorsi, and teres major in a primate (B, vervet monkey) compared to a nonprimate mammal (A, opossum). Although primates tend to have relatively longer limbs and a less crouched limb posture than other mammals of their size, the configuration of their humeral retractors does not differ substantially from that of other mammals. The asterisks indicate approximate positions of EMG electrodes. Opossum redrawn from Jenkins and Weijs (Jenkins and Weijs, 1979).