Neurological Chains

Excerpted from Page, Frank, and Lardner. Assessment and Treatment of Muscle Imbalance: The Janda Approach (2010)

Neurological chains are seen in the sensorimotor system and in neurodevelopmental movement patterns.

The sensorimotor system is linked neurologically through the afferent and efferent systems.  In controlling movement, feedback and feed forward mechanisms provide a chain reaction of neuromuscular events.  This provides both global and local stabilization of joints through muscular chains.  These sensorimotor chains are affected by afferent input, controlled by the CNS, and realized through efferent motor output.

Simply put, groups of muscles are linked together neurologically for function…

Sensorimotor chains include reflex stabilization chains and adaptation chains.

Reflex stabilization is an example of a functional neurological chain reaction. Reflex stabilization occurs subconsciously.  Muscles contract involuntarily to provide stabilization either locally or globally.  As an example, in the standing posture if an anterior weight shift occurs, the posterior dorsal muscles are activated, while a posterior weight shift activates the anterior ventral muscles.

Sensorimotor influence for spinal muscle stabilization is demonstrated by activation of the contralateral erector spinae during ipsilateral shoulder abduction.

The most important stabilizing sensorimotor chain is the pelvic chain, consisting of the TrA, multifidus, diaphragm, and pelvic floor.  These four muscles are coactivated for trunk stability and force transmission.  The pelvic chain is the cornerstone of stability for the rest of the body.  This is probably why Waslaski suggests that a pelvic stabilization sequence should be performed as the prelude to all other protocols in a pain model session.

Pelvic weakness has been associated with low back pain, groin strains, IT band syndrome, anterior knee pain, ACL tears, and ankle sprains.  Janda was one of the first to note delayed firing of the TrA in patients with chronic low back pain.  Patients with functional ankle instability change their postural stabilization by introducing a hip strategy, while subjects without instability favor an ankle strategy.

Similar pathologies are noted in the shoulder by delayed activation of the mid- and lower trapezius as well as the serratus anterior (scapular stabilization) in swimmers with shoulder impingement.

Janda identified two types of sensorimotor adaptation chains:  horizontal (anatomic) adaptation and vertical (neurological) adaptation.

Horizontal adaptation occurs when impaired function in one joint or muscle creates a reaction and adaptation in other joint segments.  It is most commonly seen in the spine, where low back pain often leads to cervical syndromes.  Muscle imbalances conform to horizontal adaptation and actually create predictable patterns that can be observed as proximal to distal or distal to proximal.  The distal to proximal pattern is seen most often in the case of ankle sprains, where researchers have found weakness and other changes in hip muscle(s) activation.

Vertical adaptation occurs between the PNS and CNS, where adaptation in one part of the sensorimotor system impairs the function of the entire system.  The adaptation can progress from the PNS to the CNS, or CNS to PNS, and can be observed as a change in the motor programming that results in abnormal movement patterns.  A good example would be where an individual with functional ankle instability exhibits altered kinematics during gait.  This type of compensation is known as a ‘feed forward’ change in the motor control program.

Neurological Locomotor Patterns

Two groups of muscles are regulated throughout the body by the CNS; the tonic muscle system and the phasic muscle system.  There are several ways to differentiate between these two groups.  Neurologically, tonic and phasic refer to their classification in neurodevelopmental movement patterns.

Tonic system muscles are older phylogenetically and are dominant.  They are involved in repetitive or rhythmic activities.  Their function is predominantly that of flexion.

Phasic system muscles are more predominant in extension movements.  They are younger phylogenetically and typically work against gravity, acting as postural stabilizers.

The tonic and phasic systems do not function individually.  They work together through coactivation for posture, gait, and coordinated movement.  Janda’s concept of muscle balance is based on an interaction of the tonic and phasic systems for optimal posture and movement.  This interaction provides for centration of joints during movement, creating a balance of muscular forces that maintain joint congruency through movement.  This is somewhat different than other concepts of muscle balance that are described only in terms of length/strength relationships.

When these two systems are coactivated in specific chains of movement, each chain is made up of a series of synergistic movements that are combined into coordinated movement patterns.  These movement patterns serve as the default motor program on which humans base more complicated movements. Upper-quarter (cervical and upper-extremity) tonic-phasic coactivation patterns are used for prehension, grasping, and reaching.  Lower-quarter (lumbar and lower-extremity) patterns are used for creeping, crawling, and gait.

Proper balance of these two systems is demonstrated in normal gait and posture.  The integration of the tonic and phasic systems between the lower and upper body is responsible for reciprocal locomotion.  Specifically, the coactivation of the contralateral upper- and lower-quarter systems throughout the body produces the characteristic patterns of reciprocal arm and leg movements.  During the swing phase, the left lower-extremity performs a tonic movement pattern (hip flexion).  At the same time the right upper-extremity performs a tonic pattern (shoulder flexion).  While the right lower-extremity performs the stance phase (hip extension) a phasic movement pattern, the left upper-extremity performs the phasic movement pattern of shoulder extension.  This demonstrates the reciprocal coactivation of the tonic and phasic systems in a movement pattern known as gait (walking).


Understanding chain reactions helps practitioners quickly identify and predict functional pathology.  The concept of chain reactions emphasizes the clinical principle of looking beyond the site of the pain to focus on the cause rather than the source of pain.

Muscular Chains

Excerpted from Page, Frank, and Lardner. Assessment and Treatment of Muscle Imbalance: The Janda Approach (2010)

Muscular chains are groups of muscles that work together or influence each other through movement patterns.  There are three types of muscular chains:  synergists, muscle slings, and myofascial chains.  Remember, each type of muscular chain is interdependant on both the articular and neurological systems.

Synergists are muscles that work together with other muscles (agonists) to produce movement or stabilization around a joint.  For example, in shoulder movement the rotator cuff is active in keeping the head of the humerus centered in the glenoid, while at the same time the rhomboid, serratus anterior and trapezius work as stabilizers of the scapula to provide a stable origin for the rotator cuff muscles.

So, synergists work together for isolated joint motion.  These muscular chains are also engaged in force coupling.  Force couples are two equal and opposite muscle forces that produce ‘pure rotation’ around a center of motion.  A good example would be how the rotator cuff and deltoid provide a force couple for shoulder abduction.  Clinicians must evaluate force coupling within a muscular chain for movement dysfunction.  In the example given, the rotator cuff should hold the head of the humerus in the center of the glenoid by exerting a downward tension while the deltoid creates an upward tension.  When they are balanced, the shoulder can move through pain-free abduction.  A typical imbalance occurs when the deltoid overpowers the rotator cuff and the head of the humerus is pulled up against the underside of the acromiom.  If the subacromial space, which is maintained by force couple balance disappears, impingement and pain can result.

While synergists work together locally for isolated joint movement…

Muscle slings act globally, providing movement and stabilization across multiple joints.  Muscle slings have been recognized in European anatomy and medicine since the 1930s.  Thomas Meyers, in his famous work Anatomy Trains (2001), provides the description of how chains of muscles that are linked together, often in loops, influence the quality of global (entire) movement patterns.

Muscle slings are believed to facilitate rotation and transfer forces through the trunk, from the lower to upper body, in particular.  Slings provide both stabilization and motion in reciprocal and contralateral movements such as gait.  Muscle slings interconnect by attaching to common ‘keystone structures’.  Keystone structures include the humerus, ribs, linea alba, femur, and tibia, in addition to the pelvis and scapulae, described previously.

While Meyers based his chains on fascial connections throughout the body, the Europeans, Vladimir Janda in particular, recognized both fascial and functional factors in muscular chains.

Extremity slings are designed for simultaneous compound movements of the limbs.

The lower-extremity extensor sling consists of the gluteus maximus, rectus femoris, and gastrocnemius for hip extension, knee extension, and ankle plantar flexion, respectively.  The iliopsoas, hamstrings, and tibialis anterior combine for hip flexion, knee flexion, and ankle dorsiflexion, respectively. scan0002

During gait, the swing phase activates the flexor chain with simultaneous hip flexion, knee flexion, and ankle dorsiflexion.  During the stance phase, the extensor sling propels the extensor sling with hip extension, knee extension, and ankle plantar flexion.

Throughout the gait cycle, these two chains alternate between facilitation and inhibition and reciprocate between the left and right limbs.  This is demonstrated when the flexor chain is activated in the swingingleg while the extensor sling is activated in the stance leg.


The upper-extremity flexor sling includes the pectoralis major, anterior deltoid, trapezius, biceps, and hand flexors.  The upper-extremity extensor sling consists of the rhomboids, posterior deltoid, triceps and hand extensors.scan0003

The upper-extremity slings are activated along with the lower-extremity slings for reciprocal gait.  During the swing phase, activation of the right upper-extremity flexor sling is coupled with the left lower-extremity extensor sling, and vice versa.

The trunk muscle slings facilitate reciprocal gait patterns between the upper and lower extremity as well as for trunk stabilization.  The three slings that have been identified are the anterior, spiral and posterior slings.

The anterior sling includes the biceps, pectoralis major, internal oblique, contralateral hip abductors, and Sartorius.scan0001 - Copy

The spiral sling, wrapping from the posterior to the anterior, includes the rhomboids, serratus anterior, external oblique, contralateral internal oblique, and contralateral hip adductors.










The posterior sling includes the hamstrings, gluteus maximus, thoracolumbar fascia, contralateral latissimus dorsi, and triceps.  This sling enables extension during reciprocal gait, trunk stabilization, and force transmission from the lower to upper body.

scan0004Understanding the function and pathsof these slings is necessary for clinicians to correctly diagnose and treat challenging musculoskeletal pain syndromes.  For example right shoulder pain may be related to left hip dysfunction, and vice versa…and may present clinically as pain, muscle imbalances, or trigger points within the sling.

Myofascial chains are critical to integrated joint movement. 

Fascia serves as the vital link to multiple muscles acting together for movement, as well as connecting the extremities through the trunk.  An example would be how the thoracolumbar fascia links the lower extremity (gluteus maximus) and the contralateral upper extremity (latissimus dorsi) transferring load across the midline to control limb extension and trunk rotation.  These facial layers help connect muscle throughout the region, creating myofascial chains.

Abdominal fascia attaches to the external oblique, internal oblique, transverse abdominus (TrA), pectoralis major, and serratus anterior.  Therein lie the links that form the diagonal muscle sling among the external oblique, pec major, and serratus anterior.

Thoracolumbar fascia attaches to the external oblique, internal oblique, TrA, latissimus dorsi, and gluteus maximus.  It consists of three layers.

The anterior fibers envelop the psoas and quadratus lumborum (QL).

The middle layer is continuous with the TrA, and attaches to the obliques and latissimus.

The posterior, possibly the most important layer, is designed to transmit forces between the shoulder girdle, lumbar spine, pelvis, and lower extremity.

It would be an understatement to suggest that clinicians could evaluate and treat chain reactions without a considerable understanding of the role fascia plays in both structure and function.

For a more complete and detailed understanding of myofascial chains, Thomas Meyers’ Anatomy Trains is indispensable.


Articular Chains

Excerpted from Page, Frank, and Lardner. Assessment and Treatment of Muscle Imbalance: The Janda Approach (2010)

Articular chains result from the biomechanical interactions of different joints throughout a movement pattern.  There are two types of articular chains:  postural and kinetic.

Postural chains describe the position of one joint in relation to another when the body is in an upright position.  They influence positioning and movement through both structural and functional mechanisms.

Structural mechanisms describe the influence of static skeletal positioning on adjacent structures.  Structural chains are influenced by static joint position.

The most recognized structural postural chain occurs throughout the spine.  The postural position of the cervical, thoracic, and lumbar spine is typically assessed in patients with musculoskeletal pain.  As depicted in the Brugger cogwheel chain mechanism of poor posture, poor posture is a chain reaction occurring throughout the spine from the position of the pelvis to the position of the head.



Poor sitting posture (left) results in a posterior pelvic tilt.  This is indicated by a counterclockwise cogwheel and indicates a reduction in the normal lordosis of the lumbar spine.  This reverses the normal kyphosis of the thoracic spine through a clockwise cogwheel, and then creates a counterclockwise rotation in the cervical spine resulting in a forward head with an extended neck…a typical example of poor posture.

To assume proper posture (right), reverse the lower cogwheel (clockwise) to rotate the pelvis anteriorly.  This in turn rotates the middle cogwheel (counterclockwise) lifting the chest upward while rotating the upper cogwheel (clockwise) stretching the neck and repositioning the head.

Functional mechanisms describe the dynamic influence that the position of the keystone structures (pelvis and scapulae) has on the muscles attaching to those structures.  Functional chains are influenced by muscular activity around joint structures.

In a functional postural chain, the postural position of keystone structures contributes to pathology and dysfunction.  Keystone structures (pelvis and scapulae) serve as attachment points for groups of postural muscles.  Muscle tightness or weakness may be caused by, or be the cause of, altered postural positioning.  The position of these structures is a key in assessment of posture and in the role these structures play in dysfunction.

For instance, the pelvis can influence the position of the adjacent lumbar spine.  It can also influence the length-tension of muscles originating from the pelvis, such as hip flexors and hamstrings.


The left image shows a balanced pelvis in the neutral position.  In the middle, we see a posteriorly rotated pelvis with short/tight hamstrings and overstretched/weak hip flexors.  On the right we see an anteriorly rotated pelvis with short/tight hip flexors and overstretched/weak hamstrings.

Kinetic chains are most often recognized as the concepts of open and closed chain movement patterns, in which the focus is on the movement of joints.

These chains can be easily identified through biomechanical assessment, such as gait assessment.  For example, a chain reaction of the lower extremity during gait is well known; foot pronation causes tibial internal rotation, which causes knee valgus and hip internal rotation.

This chain reaction can often translate to some or all of the following muscle impairments:  ipsilateral (same side) short/tight peroneals, overstretched/weak tibialis anterior; possible pes planus or plantar fasciitis; short/tight hip adductors, short TFL; overstretched/weak hip abductors, tight ITB, possible lateral knee pain.

Clearly, clinicians must look away from the site of the pain for the possible biomechanical contributions.

Chain Reactions

Excerpted from Page, Frank, and Lardner. Assessment and Treatment of Muscle Imbalance: The Janda Approach (2010)

“In patients with chronic musculoskeletal pain, the source of the pain is rarely the actual cause of the pain.  In fact, he who treats the site of pain is often lost.” (Czech physician Karel Lewit)

In order for clinicians to identify and predict functional pathology, understanding chain reactions is essential.  This requires emphasis on the clinical principle of looking beyond the site of pain and focusing on the cause of pain rather than the source of pain.  Adaptations within any chain can be helpful or harmful; the clinician must decide if these adaptations are pathological or functional.

Lewit’s colleague Vladimir Janda theorized musculoskeletal pathology as a chain reaction.  He was a strong proponent of looking elsewhere for the source of pain syndromes, often finding symptoms distant from the site of the primary complaint.

Chain reactions can be classified as articular, muscular, or neurological; but keep in mind that no system functions independently.  The type of chain reaction that develops depends on the functional demands, and depends on interaction of these three systems.  Pathology in the primary chain can be linked to dysfunction in a secondary chain, and vice versa.

  • Articular chains
  •                 Postural chains
  •                               Structural postural chains
  •                               Functional postural chains
  •                 Kinetic chains
  • Muscular chains
  •                 Synergists
  •                 Muscle Slings
  •                                 Extremity flexor and extensor slings
  •                                 Trunk muscle slings
  •                 Myofascial chains
  •                                 Abdominal fascia
  •                                 Thoracolumbar fascia
  • Neurological Chains
  •                 Protective reflexives
  •                 Sensorimotor chains
  •                                 Reflexive stabilization
  •                                 Sensorimotor adaptation chains
  •                                              HORIZONTAL ADAPTATION
  •                                              VERTICAL ADAPTATION
  •                 Neurodevelopmental  locomotor patterns
  •                                 Tonic chain
  •                                 Phasic chain