Scapular dyskinesis, or altered movement of the scapula, is not a primary diagnosis but rather a sign of underlying dysfunction that significantly compromises the entire shoulder complex. For manual therapists, understanding the mechanisms behind this condition is essential for moving beyond symptomatic treatment and addressing the kinetic chain faults that lead to chronic pain and instability in the upper extremity.

The Pathomechanics of Altered Movement

Scapular motion is dictated by the precise, synergistic action of 17 different muscles. Dyskinesis occurs when this synergy is lost, leading to poor positioning and altered movement patterns during arm elevation. This alteration is typically due to a combination of muscular imbalances and neurological inhibition.

• Muscle Inhibition and Weakness: The most common culprits are the deep stabilizers: the Serratus Anterior and the Lower Trapezius. When these muscles are weak or inhibited (often due to pain or nerve entrapment), the scapula loses its anchor against the rib cage, leading to winging (prominence of the medial border) or tipping (prominence of the inferior angle).

• Muscular Overactivity and Tightness: Conversely, overactive or tight muscles often compensate for the weakness. The Upper Trapezius and Levator Scapulae may become hypertonic, causing premature or excessive elevation of the scapula. The Pectoralis Minor is frequently short and tight, pulling the scapula into an anterior tilt and protraction, further disrupting the natural rhythm.

The Clinical Consequences of Dyskinesis

The altered mechanics of scapular movement have several critical consequences for the client:

• Compromised Subacromial Space: When the scapula fails to rotate upward correctly, the relative position of the acromion is altered. This reduces the subacromial space, making soft tissues like the rotator cuff tendons and bursa susceptible to impingement and chronic irritation during overhead movements.

• Loss of Scapulohumeral Rhythm: The ideal 2:1 ratio of glenohumeral movement to scapular movement is disrupted. This means the humerus is forced to move within a non-optimal range, leading to abnormal stress on the shoulder joint and surrounding capsular structures.

• Altered Kinetic Chain Force: The scapula acts as the central link in the kinetic chain connecting the torso to the arm. Poor scapular control reduces the efficiency of force transfer from the core to the extremity, leading to reduced power and endurance, particularly in throwing or overhead athletes. For a broader look at how these connections impact performance, see our guide on The Kinetic Chain: Enhancing Performance & Preventing Injury.The Kinetic Chain: Enhancing Performance & Preventing Injury

Part 2 Scapular Dyskinesis: Practical Assessment for Manual Therapists coming soon