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. Author manuscript; available in PMC: 2014 Apr 1.
Published in final edited form as: Ann N Y Acad Sci. 2013 Mar;1279:114–126. doi: 10.1111/nyas.12065

Figure 2.

Figure 2

Examining reproducibility of frog primitives. Stability of muscle proportionality ratios in the six main primitives are observed across frogs and across behaviors. The action of the spinal cord across the tested behaviors was to recruit the muscles in fixed ratios and thereby couple muscles so as to generate specific force-field primitives and associated preflex responses. Reflex actions (i.e., feedback effects) modulated these primitives, not individual muscles (see Ref. 53), and thus acted on their component muscles as groups. HF, hip flexor synergy. Muscle Abbrev (nomenclature of Ecker, with equivalent Abbott and Lombard): VI, vastus internus (= iliacus internus); VE, vastus externus (= iliacus externus); BI, biceps (= Iliofibularis); AD, adductor magnus; SA, sartorius; RA, rectus anticus (= quadratus femoris); GL, gluteus. Reproduced from Ref. 83, with permission.