Role of transversus abdominis muscle in spinal stability

This is a descriptive review of specific topic areas regarding the function of the transversus abdominis muscle (Tra) in context of the Tra having a central role in spinal stabilization. A literature search was made to examine the experiments supporting a spinal stabilizing role of the transversus abdominis muscle and to compare to findings of other physiological research on the functions of the Tra. The proposed generation of extension moment of the lumbar spine produced through tension of the thoracolumbar fascia or through raised intra abdominal pressure caused by the action of transversus abdominis muscle and the diaphragm does not appear to be supported by experiments. Experimental support for the stated earliest contraction of the Tra in response to perturbation appears to be lacking. There are many reports of the presence of several reflexive mechanisms by which movements of the limbs initiate respiratory activity of the Tra and of the diaphragm which could explain the activation of the Tra and the diaphragm in response to perturbation. The co contraction of the Tra and the diaphragm associated with limb movements is likely to be a respiratory response and is also likely to create the necessary transdiaphragmatic pressure for protection and containment of the thoracoabdominal viscera; a spinal stabilization role is likely to be secondary.