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Positional strategy of trunk muscles among aquatic, semi-aquatic and terrestrial species in Urodela.

Omura A, Anzai W, Koyabu D, Endo H - J. Vet. Med. Sci. (2015)

Bottom Line: Clarification of the trunk structure in Urodela is important in understanding the locomotive evolution of basal tetrapods.The components of the muscular trunk wall among Urodela using different modes of locomotion were compared.Since the whole trunk may be used for swimming and the effect of limbs may be small in the more aquatic species, they showed smaller differences in the trunk muscles among anterior, middle and posterior sections of the trunk.

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.

ABSTRACT
Clarification of the trunk structure in Urodela is important in understanding the locomotive evolution of basal tetrapods. The components of the muscular trunk wall among Urodela using different modes of locomotion were compared. Since the whole trunk may be used for swimming and the effect of limbs may be small in the more aquatic species, they showed smaller differences in the trunk muscles among anterior, middle and posterior sections of the trunk. By contrast, in the more terrestrial species, the dorsal and abdominal muscles are larger in the middle section than those in the anterior and posterior sections. High compressive stresses occur in the supporting limbs and their insertion at the trunk on the ventral side, and spread from the forelimbs along the back to the supporting hindlimbs on the dorsal side. Tensile stresses occur in the middle ventral part. The components of the trunk muscles among the three sections may reflect differences in stresses occurring in the trunk of the more terrestrial species. The findings also suggest that in the middle section, larger dorsal muscles for stiffening the back to maintain posture and larger abdominal muscles are responsible for balancing the body weight while it is supported by the limbs in the more terrestrial species.

No MeSH data available.


Related in: MedlinePlus

Resting quadruped on 2 pairs of limbs, with distribution of stresses derived frombody weight. White arrows show tension. Black distributions represent compression.Modified from Preuschoft et al. [16].
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fig_003: Resting quadruped on 2 pairs of limbs, with distribution of stresses derived frombody weight. White arrows show tension. Black distributions represent compression.Modified from Preuschoft et al. [16].

Mentions: By contrast, on the ground, the more terrestrial species need to resist downward gravity.Stresses differ according to the sections of the trunk in terrestrial species [16] (Fig. 3Fig. 3.


Positional strategy of trunk muscles among aquatic, semi-aquatic and terrestrial species in Urodela.

Omura A, Anzai W, Koyabu D, Endo H - J. Vet. Med. Sci. (2015)

Resting quadruped on 2 pairs of limbs, with distribution of stresses derived frombody weight. White arrows show tension. Black distributions represent compression.Modified from Preuschoft et al. [16].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4591143&req=5

fig_003: Resting quadruped on 2 pairs of limbs, with distribution of stresses derived frombody weight. White arrows show tension. Black distributions represent compression.Modified from Preuschoft et al. [16].
Mentions: By contrast, on the ground, the more terrestrial species need to resist downward gravity.Stresses differ according to the sections of the trunk in terrestrial species [16] (Fig. 3Fig. 3.

Bottom Line: Clarification of the trunk structure in Urodela is important in understanding the locomotive evolution of basal tetrapods.The components of the muscular trunk wall among Urodela using different modes of locomotion were compared.Since the whole trunk may be used for swimming and the effect of limbs may be small in the more aquatic species, they showed smaller differences in the trunk muscles among anterior, middle and posterior sections of the trunk.

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.

ABSTRACT
Clarification of the trunk structure in Urodela is important in understanding the locomotive evolution of basal tetrapods. The components of the muscular trunk wall among Urodela using different modes of locomotion were compared. Since the whole trunk may be used for swimming and the effect of limbs may be small in the more aquatic species, they showed smaller differences in the trunk muscles among anterior, middle and posterior sections of the trunk. By contrast, in the more terrestrial species, the dorsal and abdominal muscles are larger in the middle section than those in the anterior and posterior sections. High compressive stresses occur in the supporting limbs and their insertion at the trunk on the ventral side, and spread from the forelimbs along the back to the supporting hindlimbs on the dorsal side. Tensile stresses occur in the middle ventral part. The components of the trunk muscles among the three sections may reflect differences in stresses occurring in the trunk of the more terrestrial species. The findings also suggest that in the middle section, larger dorsal muscles for stiffening the back to maintain posture and larger abdominal muscles are responsible for balancing the body weight while it is supported by the limbs in the more terrestrial species.

No MeSH data available.


Related in: MedlinePlus