biomechanics of core muscles
DESCRIPTION
biomechanics of lumbar core muscles\ Khushali Jogani The Sarvajanik College Physiotherapy, Rmpura,Surat.TRANSCRIPT
BIOMECHANICS OF LUMBAR CORE MUSCLES
By: Khushali JoganiThe Sarvajanik College Of Physiotherapy
Rampura,Surat
Contents
What is core Models for spinal stabilization Muscles of core Biomechanics of core muscles References
What is core? CORE is defined as a clinical manifestation in
which a delicate balance of movement and stability occurs simultaneously.
The “core” has been described as a box with the abdominals in the front, paraspinals and gluteals in the back, the diaphragm as the roof, and the pelvic floor and hip girdle musculature as the bottom.
Attention to core is important because it serves as a muscular corset that works as a unit to stabilize the body and spine, with and without limb movement.
In short, the core serves as the center of the functional kinetic chain.
Stabilization of lumbar spine is provided by the passive support of the osseoligamentous structures, the support of the muscle system, and control of the muscle system by the central nervous system.
Interrelated parameters of spinal stability need to be considered due to the multisegmental nature of the lumbar spine.
Control of spinal orientation, which relates to the maintenance of the overall posture of the spine against imposed forces and compressive loading.
Control of the intersegmental relationship at the local level (i.e.lumbar segmental control), irrespective of changes in the overall orientation of the spine.
Control of lumbopelvic orientation
The main function of lumbopelvic hip region is to transfer the loads generated by the body weight and gravity during standing, walking and sitting.
Panjabi introduced an innovative model for the spinal stabilization system(effective load transfer) which serves as an appropriate model for understanding the entity of spinal stability and instability.
It included passive, active and neural control systems and all these three systems produce approximation of joint surfaces which is essential if stability is to be insured.
The amount of approximation required is variable and and difficult to quantify as it depends on individual’s structure and forces they need to control.
The integrated model of function is been proposed for managing impaired function.
It has four components:-form closure-force closure-motor control-emotional
1. Form closure - It was coined by Vleeming and snijders.- All joints have variable amount of form
closure.- Depending on individual’s anatomy –
decides the force closure.- Form of lumbar spine, pelvis &hip are
included.
The Lumbar region-compression-torsion or rotation-posteroanterior translation
The pelvic girdle
The hip
2. Force Closure If the articular surfaces of the lumbar spine,
pelvic girdle, and hip were constantly and completely compressed, mobility would not be possible. However, compression during loading is variable and therefore motion is possible and stabilization required.
This is achieved by increasing compression across
the joint surface at the moment of loading
The amount of force closure required depends on the individual's form closure and the magnitude of the load. The anatomical structures responsible for force closure are the ligaments,muscles, and fascia.
3. Motor control
4. Emotions
By active subsystem of panjabi model, muscles provides the mechanism by which control system may modulate the stability of spine.
Stability of spine is important because movement is important for optimal spinal health.
Movement is required to assist in dissipation of forces and to minimize the energy expenditure.
Core muscles
Lumbopelvic stability is provided by the core muscles.
Bergmark has categorised the trunk muscles into local and global muscle system.
Local muscle system stabilises the spinal segment whereas global muscle system act as guy ropes to support the vertebrae
Biomechanical contribution to lumbopelvic control
Anterolateral abominal paraspinal wall and abdominal muscles of cavity lumbar
region posterior abdominal wall
Anterolateral abominal wall and abdominal cavity
Global muscles(obliquus internus abdominis, obliquus externus abdominis, rectus abdominis
Transversus abdominis Diaphragm and pelvic floor
Global muscles-Four slings of muscle system stabilizes the
pelvis regionally.-posterior, anterior, longitudinal, lateral slings-Individual muscles are important for regional
stabilization and mobility and it is necessary to understand how they connect and function togather.
-Muscle contraction-production of forces-transfer of forces-transfer of load-increases the stiffness of SIJ
-Global muscle-integrated sling system.-participation of muscle in more than one sling-
overlap & interconnect-depending on task
-obliquus externus abdominis make a powerful contribution to control of buckling forces
-contribution to lumbopelvic movement and stabilization is based on moment arm and direction of forces.
-if high loads are unpredictable, muscles on both sides are coactivated to stiffen the trunk.
Transversus abdominis- Due to transverse orientation of muscle it
has limited ability to flex, extend or laterally flex the spine.
- Limited moment arm to contribute to rotatory torque.
- Contribution through spinal buckling.- Though contribution is small,it produces
very efficient effect.- Modulation via intra-abdominal
pressure(IAP), fascial tension and compression of sacaroiliac joint
Intra-abdominal pressure-IAP in daily activities-abdominal cavity as ‘pressurized balloon’-production of extension torque and offset of
flexion moment by abdominal muscle-TrA is the most active of abdominal muscles
in extension efforts.-concurrent flexion and extension moments
may increase spinal stiffness like co-contraction.
-IAP increase spinal stiffness
Fascial tension-thoracolumbar fascia and contribution to
spinal stiffness-TrA muscle and its attachment to
thoracolumbar fascia.-Mechanics of thoracolumbar fascia-control of intersegmental motion via lateral
tension in thoracolumbar fascia.-stabilization of lumbar spine in coronal
plane via tension in middle layer of thoracolumbar fascia.
Pelvic stability-mechanism of stability of sacro-iliac joint is
dependent on compression between ilium and sacrum.
Diaphragm and pelvic floor-contribution through IAP and restriction of
movement of abdominal viscera for spinal stability
Posterior abdominal wall Psoas-it has tendency to overactivity and
tightness -two separate muscles and contribution of
posterior fibres for control of intervertebral motion.
Quadratus lumborum-its medial fibres through the attachment to
lumbar vertebral transverse processes is capable of providing segmental stability via its segmental attchment
Paraspinal muscles of lumbar region
Intersegmental muscles-intertransversarii-interspinales Lumbar muscles-lumbar multifidus-longissimus thoracis-iliocostalis lumborum
Biomechanical factors-control of neutral zone-control of lordosis-tensioning the thoracolumbar fascia-control of shear forces
Control of neutral zone-lumbar muscles increase the spinal
segmental stiffness and control of neutral zone
-increased combined muscle activation-muscle forces decrease the sagittal plane
displacement ,anterior rotation and anteroposterior translation
-load bearing surface of zygoapophyseal joints
-intersegmental nature of multifidus
Control of lordosis-spinal curves efficient to deal with force of
gravity-role of mulitifidus-local and global muscles increase the
capacity of spine to withstand the compressive forces without buckling.
Tensioning the thoracolumbar fascia-muscle enhance the spinal stability by
increasing stiffness of spinal segment-thoracolumbar fascia contributes to lumbar
stabilization by increasing the bending stiffness of spine.
Control of shear forces-shear forces are those that cause the
vertebrae to slide with respect to one another
-control of anterior shear forces-Provided by passive elements as well as
muscles-lumbar extensor muscles helps in
controlling
References
Carolyn Richardson,Paul Hodges,Julie Hides Therapeutic exercise for lumbopelvic stabilization. second edition.
Diane Lee,Paul Hodges,The pelvic Girdle,an approch to the examination and treatment of the lumbopelvic-hip region.Third edition.
Carolyn Richardson,Gwendolen Jull, Julie Hides,Paul Hodges. Therapeutic exercise for spinal segmental stabilization in low back pain