Activity of trunk muscles during aquatic and terrestrial locomotion inAmbystoma maculatum

Abstract

SUMMARYThe activity of seven trunk muscles was recorded at two sites along the trunk in adult spotted salamander, Ambystoma maculatum, during swimming and during trotting in water and on land. Several muscles showed patterns of activation that are consistent with the muscles producing a traveling wave of lateral bending during swimming and a standing wave of bending during aquatic and terrestrial trotting: the dorsalis trunci, subvertebralis lateralis and medialis, rectus lateralis and obliquus internus. The interspinalis showed a divergent pattern and was active out of phase with the other muscles suggesting that it functions in vertebral stabilization rather than lateral bending. The obliquus internus and rectus abdominis showed bilateral activity indicating that they counteract sagittal extension of the trunk that is produced when the large dorsal muscles are active to produce lateral bending. Of the muscles examined, only the obliquus internus showed a clear shift in function from lateral bending during swimming to resistance of long-axis torsion during trotting. During terrestrial trotting, muscle recruitment was greater in several muscles than during aquatic trotting, despite similar temporal patterns of muscle activation, suggesting that the trunk is stiffened during terrestrial locomotion against greater gravitational forces whereas the basic functions of the trunk muscles in trotting are conserved across environments.

Function of the epaxial muscles in walking, trotting and galloping dogs: implications for the evolution of epaxial muscle function in tetrapods

“…Retractor activity data: salamander, Dicamptodon tenebrosus, m. caudofemoralis (AshleyRoss, 1995); lizard, Dipsosaurus dorsalis, m. caudofemoralis (Nelson and Jayne, 2001); mammal, Canis familiaris, m. semimembranosus (Schilling et al, 2009) (N.S., S. M. Deban and D.R.C., unpublished data). For the salamander and the trotting dog, bending traces above the EMGs illustrate the unimodal lateral and the bimodal sagittal bending of the trunk during the course of a stride (from Deban and Schilling, 2009;Ritter et al, 2001). Body planes in which moments and/or movements are suggested to occur are illustrated in the right top corner of each graph (for details see B).…”

“…During terrestrial locomotion, both kinematic and electromyographic results point to a standing wave of lateral bending, resulting from coordinated epaxial and hypaxial muscle activity (Roos, 1964;Frolich and Biewener, 1992;Carrier, 1993). The main epaxial muscle, active during the second half of ipsilateral hindlimb support and throughout the swing phase (Fig.4A), was shown to laterally bend the trunk but also to provide postural stability during terrestrial stepping (Deban and Schilling, 2009). Additional activity close to the limb girdles stabilizes the trunk against extrinsic limb muscle action (Delvolve et al, 1997).…”

Where are we in understanding salamander locomotion: biological and robotic perspectives on kinematics

“…Duty factor is greatly reduced during aquatic stepping such that the resulting footfall patterns resemble a running trot with short periods of suspension (Fig. 3 in Ashley-Ross et al 2009;Deban and Schilling 2009). Another difference is the switch from a lateral to a diagonal sequence walk when salamanders transit from a terrestrial to an aquatic environment (Ashley-Ross 1994a).…”

“…Cinematography has been used by many investigators early on (e.g., Gray 1944;Evans 1946) to study the kinematics of salamanders. Force-plate measurements (Barclay 1946;Sheffield and Blob 2011) and electromyography (e.g., Székely et al 1969;Frolich and Biewener 1992;Ashley-Ross 1995;Delvolvé et al 1997;Deban and Schilling 2009) helped to understand their dynamics and muscular activity patterns. Using cineradiography, we were recently able to record and reconstruct the kinematics of the salamander's skeleton in great detail (Karakasiliotis et al, under preparation).…”

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

“…Urodele amphibians are often chosen as models to infer the evolution of locomotion of early tetrapods, because they possess a “generalized” body form and amphibious lifestyle [5]. Urodela use their body in an undulatory manner for locomotion both in water and on ground [5].…”