Kinesiology of the Trunk:
by Brent Brookbush MS, PES, CES, CSCS, ACSM H/FS
Trunk Flexion
- Prime Mover: Rectus Abdominis
- Synergists: External Obliques , Internal Obliques , Psoas
- Antagonists: Erector Spinae (Iliocostalis, Longissimus, Spinalis) , Latissimus Dorsi
- Neutralizers: External obliques and internal obliques when bilaterally contracted neutralize rotation.
- Stabilizers: Intrinsic stabilization subsystem (Transverse abdominis , intrinsic muscles of spine, diaphragm, pelvic floor)
- Fixators: All musculature of the hip especially the glute complex
Trunk Extension
- Prime Movers: Erector spinae (Iliocostalis, longissimus, spinalis) , latissimus dorsi , Intrinsic musculature of the spine
- Synergists: Intrinsic musculature of the spine
- Antagonists: Rectus abdominis , external obliques , internal obliques , psoas
- Neutralizers: Bilateral contraction of erector spinae and quadratus lumborum
- Stabilizers: Intrinsic stabilization subsystem (Transverse abdominis , intrinsic muscles of spine, diaphragm, pelvic floor)
- Fixators: All musculature of the hip especially the glute complex
Trunk Lateral Flexion
- Agonists: Quadratus Lumborum
- Synergists: Ipsilateral external oblique and internal oblique , ipsilateral erector spinae , ipsilateral latissimus dorsi
- Antagonists: Contralateral quadratus lumborum , contralateral external and internal obliques , contralateral erector spinae , contralateral latissimus dorsi
- Neutralizers: Erector spinae neutralizes flexion force created by internal and external obliques , intrinsic stabilization system creates posterior shear force on lumbar spine to neutralize lumbar extension, rectus abdominis and psoas prevent ancillary extension.
- Stabilizers: Rectus abdominis , psoas , intrinsic stabilization subsystem (Transverse abdominis , intrinsic muscles of spine, diaphragm, pelvic floor)
- Fixators: All musculature of the hip especially the glute complex
Trunk Rotation
- Prime Movers: Contralateral external oblique and ipsilateral internal oblique
- Synergists: Ipsilateral latissimus dorsi , contralateral psoas
- Antagonists: Opposing external and internal oblique
- Neutralizers: Erector spinae neutralize the flexion force created by the internal and external obliques , quadratus lumborum neutralizes lateral flexion force created by the internal and external obliques , and rectus abdominis prevent ancillary lumbar extension (anterior pelvic tilt) created by the latissimus dorsi
- Stabilizers: Intrinsic stabilization subsystem (Transverse abdominis , intrinsic muscles of spine, diaphragm, pelvic floor)
- Fixators: All musculature of the hip especially the glute complex
Trunk Flexion and Rotation
- Prime Movers: Rectus abdominis , contralateral external oblique , ipsilateral internal oblique
- Synergists: Ipsilateral latissimus dorsi , contralateral psoas
- Antagonists: Opposing external and internal oblique , erector spinae
- Neutralizers: Quadratus lumborum neutralizes lateral flexion force created by the internal and external obliques
- Stabilizers: Intrinsic stabilization subsystem (Transverse abdominis , intrinsic muscles of spine, diaphragm, pelvic floor)
- Fixators: All musculature of the hip especially the glute complex
Trunk Extension w/ Rotation
- Prime Movers: Erector spinae (iliocostalis, longissimus, spinalis) , contralateral external oblique , ipsilateral internal oblique , latissimus dorsi
- Synergists – Latissimus dorsi , contralateral psoas
- Antagonists – Rectus abdominis , ipsilateral external obliques , contralateral internal obliques , ipsilateral psoas
- Neutralizers: Quadratus lumborum neutralizes lateral flexion force created by the internal and external obliques
- Stabilizers: Intrinsic stabilization subsystem (Transverse abdominis , intrinsic muscles of spine, diaphragm, pelvic floor)
- Fixators: All musculature of the hip especially the glute complex
© 2011 Brent Brookbush
Questions, comments, and criticisms are welcomed and encouraged –