This cross-sectional study measured 3D scapular orientation and muscle activity in 25 asymptomatic subjects at 0°, 90°, and 140° of humeral elevation in the scapular plane. It provides normative values for all three axes of scapular rotation alongside EMG data from four scapulothoracic muscles. The central question: what does normal scapular motion actually look like, and which muscles drive it?
Before this paper, clinical scapular assessment focused almost exclusively on upward rotation, a 2D concept inherited from decades of cadaver and plain-radiograph research. Tipping and internal/external rotation were recognized anatomically but rarely measured or linked to specific pathologies.
This paper is why we now assess scapular dyskinesis in three planes. When a patient presents with impingement symptoms and you find limited posterior tipping on dynamic assessment, that is a mechanical explanation: the anterior acromion cannot clear the cuff without posterior scapular tipping. When you see excessive internal rotation (antetilt) in an overhead thrower, that is a risk factor for anterior labral stress and instability.
For rehabilitation, the data point directly at serratus anterior as the primary driver of all three normal scapular rotations. Pectoralis minor tightness restricts posterior tipping; levator scapulae and rhomboid tightness restricts upward rotation. Stretching these before strengthening serratus addresses the mechanical deficit, not just the symptom.
The lower trapezius finding is a practical reminder: at high elevation angles, lower trap activation is inconsistent across normal individuals, so its absence alone cannot be called pathological without knowing the patient's full kinematic pattern.
This cross-sectional study measured 3D scapular orientation and muscle activity in 25 asymptomatic subjects at 0°, 90°, and 140° of humeral elevation in the scapular plane. It provides normative values for all three axes of scapular rotation alongside EMG data from four scapulothoracic muscles. The central question: what does normal scapular motion actually look like, and which muscles drive it?
Before this paper, clinical scapular assessment focused almost exclusively on upward rotation, a 2D concept inherited from decades of cadaver and plain-radiograph research. Tipping and internal/external rotation were recognized anatomically but rarely measured or linked to specific pathologies.
This paper is why we now assess scapular dyskinesis in three planes. When a patient presents with impingement symptoms and you find limited posterior tipping on dynamic assessment, that is a mechanical explanation: the anterior acromion cannot clear the cuff without posterior scapular tipping. When you see excessive internal rotation (antetilt) in an overhead thrower, that is a risk factor for anterior labral stress and instability.
For rehabilitation, the data point directly at serratus anterior as the primary driver of all three normal scapular rotations. Pectoralis minor tightness restricts posterior tipping; levator scapulae and rhomboid tightness restricts upward rotation. Stretching these before strengthening serratus addresses the mechanical deficit, not just the symptom.
The lower trapezius finding is a practical reminder: at high elevation angles, lower trap activation is inconsistent across normal individuals, so its absence alone cannot be called pathological without knowing the patient's full kinematic pattern.