Shoulder external rotation (or lateral rotation) is a rotary movement at the shoulder (glenohumeral) joint around the longitudinal axis of the humerus (upper arm bone) away from the centre of the body – turning the upper arm outwards – see Figures 1 and 2.
Figure 1. Shoulder External Rotation.
Figure 2. Shoulder external rotation with cable.
The key muscles involved in this movement are the posterior deltoid, the infraspinatus, and the teres minor. The supraspinatus also plays a weak role when the shoulder is abducted.
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