Which phase of scapulohumeral rhythm involves little to no motion of the scapula?

The phase of scapulohumeral rhythm that involves little to no motion of the scapula is the first phase. During this initial phase, shoulder abduction or flexion begins primarily at the glenohumeral joint without significant movement of the scapula. This means that as the arm is lifted up, the scapula remains relatively stable and allows for the mechanisms at the shoulder joint to initiate the movement effectively.

This phase primarily focuses on glenohumeral movements because the deltoid and rotator cuff muscles are actively engaged in lifting the arm, while scapular stabilization occurs. Therefore, the limited mobility of the scapula in this phase highlights the emphasis on the shoulder joint's action, which is crucial for the correct initiation of overhead movements.

The subsequent phases of scapulohumeral rhythm are characterized by increased cooperation between the scapula and humerus. As the arm continues to elevate, scapular motion becomes more prominent, leading to a coordinated motion that allows for full range of motion and proper joint mechanics. Understanding this initial phase is essential for comprehending the overall dynamics of shoulder movement during various activities.