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Locomotion pattern and trunk musculoskeletal architecture among Urodela.

Omura A, Ejima KI, Honda K, Anzai W, Taguchi Y, Koyabu D, Endo H - Acta Zool (2014)

Bottom Line: Our results suggest that larger lateral hypaxial muscles function for lateral bending during underwater locomotion in aquatic species.The more aquatic species possessed a more horizontal prezygapophyseal angle for more flexible lateral locomotion.Thus, we conclude trunk structure in urodeles differs clearly according to their locomotive modes.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Agricultural and Life Sciences, The University Museum, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan ; The University Museum, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.

ABSTRACT

We comparatively examined the trunk musculature and prezygapophyseal angle of mid-trunk vertebra in eight urodele species with different locomotive modes (aquatic Siren intermedia, Amphiuma tridactylum, Necturus maculosus and Andrias japonicus; semi-aquatic Cynops pyrrhogaster, Cynops ensicauda; and terrestrial Hynobius nigrescens, Hynobius lichenatus and Ambystoma tigrinum). We found that the more terrestrial species were characterized by larger dorsal and abdominal muscle weight ratios compared with those of the more aquatic species, whereas muscle ratios of the lateral hypaxial musculature were larger in the more aquatic species. The lateral hypaxial muscles were thicker in the more aquatic species, whereas the M. rectus abdominis was more differentiated in the more terrestrial species. Our results suggest that larger lateral hypaxial muscles function for lateral bending during underwater locomotion in aquatic species. Larger dorsalis and abdominal muscles facilitate resistance against sagittal extension of the trunk, stabilization and support of the ventral contour line against gravity in terrestrial species. The more aquatic species possessed a more horizontal prezygapophyseal angle for more flexible lateral locomotion. In contrast, the more terrestrial species have an increasingly vertical prezygapophyseal angle to provide stronger column support against gravity. Thus, we conclude trunk structure in urodeles differs clearly according to their locomotive modes.

No MeSH data available.


Related in: MedlinePlus

—Cross-sections through the mid-trunk of —A. Siren intermedia, —B. Cynops ensicauda, —C. Hynobius lichenatus. Scale bar = 5 mm.
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fig04: —Cross-sections through the mid-trunk of —A. Siren intermedia, —B. Cynops ensicauda, —C. Hynobius lichenatus. Scale bar = 5 mm.

Mentions: The relative area occupied by each muscle in the cross-section of the trunk in the three species of salamanders is shown in Fig.4. The number of muscle layers and characteristics of each muscle differed among species. Three layers (M. obliquus externus, M. obliquus internus and M. transversus abdominis) composed the lateral hypaxial musculature of S. intermedia. In this species, the M. rectus abdominis was not differentiated from the lateral hypaxial muscles whereas the lateral hypaxial muscles were relatively thick. The lateral hypaxial muscles of C. ensicauda consisted of four layers: M. obliquus externus superficialis, M. obliquus externus profundus, M. obliquus internus and M. transversus abdominis. The lateral hypaxial muscles of C. ensicauda were comparatively thin. C. ensicauda possessed M. rectus lateralis, and M. subvertebralis of C. ensicauda was connected with M. transversus abdominis. M. rectus abdominis of C. ensicauda was differentiated from the lateral hypaxial musculature. Two layers composed the lateral hypaxial muscles of Hynobius lichenatus: M. obliquus externus and M. transversus abdominis. H. lichenatus had thinner lateral hypaxial muscles. H. lichenatus possessed M. rectus profundus, which was differentiated from M. rectus abdominis.


Locomotion pattern and trunk musculoskeletal architecture among Urodela.

Omura A, Ejima KI, Honda K, Anzai W, Taguchi Y, Koyabu D, Endo H - Acta Zool (2014)

—Cross-sections through the mid-trunk of —A. Siren intermedia, —B. Cynops ensicauda, —C. Hynobius lichenatus. Scale bar = 5 mm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4402012&req=5

fig04: —Cross-sections through the mid-trunk of —A. Siren intermedia, —B. Cynops ensicauda, —C. Hynobius lichenatus. Scale bar = 5 mm.
Mentions: The relative area occupied by each muscle in the cross-section of the trunk in the three species of salamanders is shown in Fig.4. The number of muscle layers and characteristics of each muscle differed among species. Three layers (M. obliquus externus, M. obliquus internus and M. transversus abdominis) composed the lateral hypaxial musculature of S. intermedia. In this species, the M. rectus abdominis was not differentiated from the lateral hypaxial muscles whereas the lateral hypaxial muscles were relatively thick. The lateral hypaxial muscles of C. ensicauda consisted of four layers: M. obliquus externus superficialis, M. obliquus externus profundus, M. obliquus internus and M. transversus abdominis. The lateral hypaxial muscles of C. ensicauda were comparatively thin. C. ensicauda possessed M. rectus lateralis, and M. subvertebralis of C. ensicauda was connected with M. transversus abdominis. M. rectus abdominis of C. ensicauda was differentiated from the lateral hypaxial musculature. Two layers composed the lateral hypaxial muscles of Hynobius lichenatus: M. obliquus externus and M. transversus abdominis. H. lichenatus had thinner lateral hypaxial muscles. H. lichenatus possessed M. rectus profundus, which was differentiated from M. rectus abdominis.

Bottom Line: Our results suggest that larger lateral hypaxial muscles function for lateral bending during underwater locomotion in aquatic species.The more aquatic species possessed a more horizontal prezygapophyseal angle for more flexible lateral locomotion.Thus, we conclude trunk structure in urodeles differs clearly according to their locomotive modes.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Agricultural and Life Sciences, The University Museum, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan ; The University Museum, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.

ABSTRACT

We comparatively examined the trunk musculature and prezygapophyseal angle of mid-trunk vertebra in eight urodele species with different locomotive modes (aquatic Siren intermedia, Amphiuma tridactylum, Necturus maculosus and Andrias japonicus; semi-aquatic Cynops pyrrhogaster, Cynops ensicauda; and terrestrial Hynobius nigrescens, Hynobius lichenatus and Ambystoma tigrinum). We found that the more terrestrial species were characterized by larger dorsal and abdominal muscle weight ratios compared with those of the more aquatic species, whereas muscle ratios of the lateral hypaxial musculature were larger in the more aquatic species. The lateral hypaxial muscles were thicker in the more aquatic species, whereas the M. rectus abdominis was more differentiated in the more terrestrial species. Our results suggest that larger lateral hypaxial muscles function for lateral bending during underwater locomotion in aquatic species. Larger dorsalis and abdominal muscles facilitate resistance against sagittal extension of the trunk, stabilization and support of the ventral contour line against gravity in terrestrial species. The more aquatic species possessed a more horizontal prezygapophyseal angle for more flexible lateral locomotion. In contrast, the more terrestrial species have an increasingly vertical prezygapophyseal angle to provide stronger column support against gravity. Thus, we conclude trunk structure in urodeles differs clearly according to their locomotive modes.

No MeSH data available.


Related in: MedlinePlus