title: Anticipatory postural activity of the deep trunk muscles differs between anatomical regions based on their mechanical advantage.
abstract: The functional differentiation between regions of psoas major (PM) and quadratus lumborum (QL) may underlie a mechanical basis for recruitment of motor units across the muscle. These mechanically unique fascicle regions of these complex multifascicular muscles, PM and QL, are likely to be controlled independently by the central nervous system (CNS). Fine-wire electrodes recorded the electromyographic activity of the PM fascicles arising from the transverse process (PM-t) and vertebral body (PM-v) and the anterior (QL-a) and posterior (QL-p) layers of QL on the right side during a postural perturbation associated with rapid arm movements. The findings of this study indicate that the CNS coordinates the activity of specific regions of PM and QL independently as a component of the anticipatory postural adjustments that precedes the predictable challenge to the spine associated with limb movements. The spatial and temporal features of discrete activity of different regions within PM and QL matched their differing mechanical advantage predicted from their anatomy. These findings suggest that the CNS differentially activates individual regions within complex spine muscles to control the three-dimensional forces applied to the spine. The data also point to a sophisticated control of muscle activation that appears based on mechanical advantage.
authors.affiliation: The University of Queensland, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, Brisbane, Queensland, Australia; The University of Queensland, Centre for Sensorimotor Neuroscience, School of Human Movement Studies, Brisbane, Queensland, Australia.
authors.forename: R J
authors.initials: RJ
authors.lastname: Park
authors.affiliation: The University of Queensland, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, Brisbane, Queensland, Australia.
authors.forename: H
authors.initials: H
authors.lastname: Tsao
authors.affiliation: The University of Queensland, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, Brisbane, Queensland, Australia; The University of Queensland, Centre for Sensorimotor Neuroscience, School of Human Movement Studies, Brisbane, Queensland, Australia.
authors.forename: A G
authors.initials: AG
authors.lastname: Cresswell
authors.affiliation: The University of Queensland, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, School of Health and Rehabilitation Sciences, Brisbane, Queensland, Australia. Electronic address: p.hodges@uq.edu.au.
authors.forename: P W
authors.initials: PW
authors.lastname: Hodges
mesh_terms: D001132:Arm / Q000502:physiology; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008959:Models, Neurological; D009068:Movement / Q000502:physiology*; D064170:Paraspinal Muscles / Q000033:anatomy & histology / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D016658:Psoas Muscles / Q000033:anatomy & histology / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult
keywords: fine-wire electromyography; lumbar spine; postural control; trunk muscles