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Epaxial muscle fiber architecture favors enhanced excursion and power in the leaper Galago senegalensis.

Publication ,  Journal Article
Huq, E; Wall, CE; Taylor, AB
Published in: J Anat
October 2015

Galago senegalensis is a habitual arboreal leaper that engages in rapid spinal extension during push-off. Large muscle excursions and high contraction velocities are important components of leaping, and experimental studies indicate that during leaping by G. senegalensis, peak power is facilitated by elastic storage of energy. To date, however, little is known about the functional relationship between epaxial muscle fiber architecture and locomotion in leaping primates. Here, fiber architecture of select epaxial muscles is compared between G. senegalensis (n = 4) and the slow arboreal quadruped, Nycticebus coucang (n = 4). The hypothesis is tested that G. senegalensis exhibits architectural features of the epaxial muscles that facilitate rapid and powerful spinal extension during the take-off phase of leaping. As predicted, G. senegalensis epaxial muscles have relatively longer, less pinnate fibers and higher ratios of tendon length-to-fiber length, indicating the capacity for generating relatively larger muscle excursions, higher whole-muscle contraction velocities, and a greater capacity for elastic energy storage. Thus, the relatively longer fibers and higher tendon length-to-fiber length ratios can be functionally linked to leaping performance in G. senegalensis. It is further predicted that G. senegalensis epaxial muscles have relatively smaller physiological cross-sectional areas (PCSAs) as a consequence of an architectural trade-off between fiber length (excursion) and PCSA (force). Contrary to this prediction, there are no species differences in relative PCSAs, but the smaller-bodied G. senegalensis trends towards relatively larger epaxial muscle mass. These findings suggest that relative increase in muscle mass in G. senegalensis is largely attributable to longer fibers. The relative increase in erector spinae muscle mass may facilitate sagittal flexibility during leaping. The similarity between species in relative PCSAs provides empirical support for previous work linking osteological features of the vertebral column in lorisids with axial stability and reduced muscular effort associated with slow, deliberate movements during anti-pronograde locomotion.

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Published In

J Anat

DOI

EISSN

1469-7580

Publication Date

October 2015

Volume

227

Issue

4

Start / End Page

524 / 540

Location

England

Related Subject Headings

  • Muscle, Skeletal
  • Muscle Fibers, Skeletal
  • Muscle Contraction
  • Locomotion
  • Galago
  • Animals
  • Anatomy & Morphology
  • 3109 Zoology
  • 1116 Medical Physiology
  • 0903 Biomedical Engineering
 

Citation

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Huq, E., Wall, C. E., & Taylor, A. B. (2015). Epaxial muscle fiber architecture favors enhanced excursion and power in the leaper Galago senegalensis. J Anat, 227(4), 524–540. https://doi.org/10.1111/joa.12351
Huq, Emranul, Christine E. Wall, and Andrea B. Taylor. “Epaxial muscle fiber architecture favors enhanced excursion and power in the leaper Galago senegalensis.J Anat 227, no. 4 (October 2015): 524–40. https://doi.org/10.1111/joa.12351.
Huq, Emranul, et al. “Epaxial muscle fiber architecture favors enhanced excursion and power in the leaper Galago senegalensis.J Anat, vol. 227, no. 4, Oct. 2015, pp. 524–40. Pubmed, doi:10.1111/joa.12351.
Journal cover image

Published In

J Anat

DOI

EISSN

1469-7580

Publication Date

October 2015

Volume

227

Issue

4

Start / End Page

524 / 540

Location

England

Related Subject Headings

  • Muscle, Skeletal
  • Muscle Fibers, Skeletal
  • Muscle Contraction
  • Locomotion
  • Galago
  • Animals
  • Anatomy & Morphology
  • 3109 Zoology
  • 1116 Medical Physiology
  • 0903 Biomedical Engineering