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Architectural Correlates of Locomotion in the Hindlimb Muscles of Two Guenon Species. Introduction. The investigation: can muscle architectural differences be recognized as the correlates of particular locomotor habits?. Muscle Architecture. The Species:. Cercopithecus aethiops C. ascanius.
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Architectural Correlates of Locomotion in the Hindlimb Muscles of Two Guenon Species
Introduction The investigation: can muscle architectural differences be recognized as the correlates of particular locomotor habits?
The Species: Cercopithecusaethiops C. ascanius
Muscles of the Hindlimb • Gluteal group • Gluteus superficialis • Gluteus medius • Gluteus minimus • Hamstrings • Biceps femoris • Semi-membranosus • Semi-tendinosus
Length of the fasciculus between the proximal myotendinous junction and the distal myotendinous junction (lf) The perpendicular distance from the tendon of insertion to the proximal attachment of fasciculus (a) Length of tendon from the proximal attachment (tp ) Length of the tendon of distal attachment (td) Morphometrics
Variables Calculated to Estimate Output Potential of the Muscles • Reduced physiological cross-sectional area RPCA (sq cms) = (mass x cos q/ lf (cms) x specific density • Mass/predicted effective maximal tetanic tension m/po, where po » 2.3 newtons x RPCA • Estimated maximum excursion of distal tendon of attachment h = lf (cos q - (Ö cos q 2 + n2 - 1) • Tendon length/fasciculus length+tendon length lt/lf + lt
Conclusions • Between group differences: intermuscular variability greater among gluteal muscles than among hamstrings. • Interspecific differences: • - Higher relative values for RPCA of gluteus medius than g. Minimus in vervets related to demands of ground quadrupedalism. • - In vervets muscles are designed for higher velocities, but greater force generation in red-tails. • - Vervet muscles designed more for isotonic contraction, by contrast to more isometric use in red-tails.