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  • Writer's pictureRobin R Varghese, PT.

"Scapular stability" and it's importance.

  • Maintaining scapular mechanics is important for upper extremity functionality and posture.(1)

  • Previously, the scapular musculature was often neglected in designing a rehabilitation protocol for the shoulder. In the past two decades a significant amount of research has been performed in order to help identify the role of the scapula in upper extremity function.(2)

  • Scapular stability refers to strong shoulder girdle muscles that plays an important role in performance of normal scapular motion.(3)

  • These muscles that surround the scapula (shoulder blade) and are along with the rotator cuff are crucial in maintaining normal shoulder function and biomechanics.

  • One will be at risk for shoulder injury if not properly supported by strong muscles – those muscles being the rotator cuff and scapular stabilizers

  • The muscles that make up the scapular stabilizers group are the:

Serratus Anterior

Trapezius muscles: Upper/Middle/Lower

Levator Scapula

Rhomboid

  • These muscles work synergistically with the deltoid and rotator cuff muscles to upwardly or downwardly rotate the scapula while the shoulder joint/arm is moving overhead, behind the back or reaching away from your trunk

Biomechanics

  • The scapular muscles must dynamically position the glenoid so that efficient glenohumeral movement can occur.

  • When weakness or dysfunction of the scapular musculature is present, normal scapular positioning and mechanics may become altered.

  • When the scapula fails to perform its stabilization role, shoulder complex function is inefficient, which can result not only in decreased neuromuscular performance but also may predispose the individual to injury of the glenohumeral joint.

  • Weakness of the scapular stabilizers and resultant altered biomechanics could result in:

1) abnormal stresses to the anterior capsular structures of the shoulder,

2) increased possibility of rotator cuff compression, and

3) decreased shoulder complex neuromuscular performance.

  • Stability of the scapulothoracic joint depends on coordinated activity of the surrounding musculature.

  • The scapulothoracic articulation is one of the least congruent joints in the body.

  • No actual bony articulation exists between the scapula and thorax, which allows tremendous mobility in many directions including protraction, retraction, elevation, depression, anterior/posterior tilt, and internal/external and upward/downward rotation.

  • The lack of an actual bony articulation in the scapulothoracic region predisposes it to pathologic movement, rendering the glenohumeral joint highly dependent on it for stability and normal motion.

  • The scapula is only attached to the thorax by ligamentous attachments at the acromioclavicular joint and through a suction mechanism provided by the muscular attachments of the serratus anterior and subscapularis.

  • This suction mechanism holds the scapula in close proximity to the thorax and allows it to glide during movements of the joint.

  • The glenohumeral “protectors” include the muscles of the rotator cuff: the supraspinatus, infraspinatus, teres minor, and subscapularis.

  • These muscle groups function through synergistic co‐contraction to anchor the scapula and guide movement.

  • Serratus anterior- the primary role of the serratus anterior is to stabilize the scapula during elevation and to pull the scapula forward and around on the thoracic cage. or upwardly rotate the scapula

  • The rhomboids- (major and minor) function to stabilize the medial border of the scapula. The rhomboids are very active in scapular adduction or retraction, which can be defined as backward rotation of the scapula toward the vertebral column.

  • Trapezius – Upper fibers that elevate and upwardly rotate the scapula.

Middle fibers Retracts the scapula.

Lower fibers depresses and rotates the scapula upwards

  • Levator Scapulae -The levator scapulae functions to elevate the scapula and tilt the glenoid cavity inferiorly by rotating the scapula downward.


Scapular Stabilizing exercise

  • The scapular stabilization exercises also aim to facilitate energy transfer through the kinetic chain. An essential part of rehabilitating the kinetic chain therefore involves exercises that transfer energy from the trunk to the arm

  • Exercises which strengthen these muscles should be combined with exercises to strengthen the rotator cuff as cuff fatigue may lead to secondary scapular dyskinesia.

  • Early rehabilitation should aim to improve the endurance and strength of the scapular stabilizing muscles.

  • Low weight, high repetition exercises promote muscle hypertrophy and improve fatigue resistance.

  • Once more normal scapular mechanics have been restored, higher weights with lower repetitions may be used to promote power.

  • Rotator cuff strengthening can begin once a stable scapular base has been restored

  • Once endurance and strength have improved, exercises that promote effective energy transfer through the kinetic chain should be added

  • Your Physical Therapist will help in promoting normal scapulohumeral rhythm and improve the body’s ability to position the scapula for stable energy transfer during functional activities.

  • It is imperative that you do not progress your scapula stability exercises too quickly, as this area requires very specific and slow strengthening. Your physical therapist will be the right guide.(4)

Researches:

  • Borstad and Ludewig found increased internal rotation and anterior tilting of the scapula in subjects with a short pectoralis minor. Therefore manual therapy and stretching of tight structures can be employed early in the rehabilitative process.

  • Scapular Stabilization Exercise could be considered an effective intervention for patients with nonspecific Neck pain.(5)

  • Three‐dimensional studies have shown that the serratus anterior contributes to all components of 3‐D scapular movements during arm elevation, which includes upward rotation, posterior tilt, and external rotation

  • training the scapular stabilizers will lead to improved athletic shoulder function and performance and a healthier pain-free shoulder joint.

  • Most shoulder complex injuries incurred as a result of sport activities can be traced to abnormal biomechanics, which, in turn, can be related to improper functioning of the scapular muscles.


Sources:






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