Postural Restoration Institute Practice Test

Improving the zone of apposition on the left side changes how the left hemidiaphragm and left rib cage sit and move, which in PRI translates to better thorax stability and alignment. When the left ZOA is enhanced, the left diaphragmatic dome can descend more effectively and the left lower ribs can stack in a more stable position. This reduces leftward rib flare and thoracic rotation, helping the thorax to balance more symmetrically. That realignment of the trunk alters the position of the scapulothoracic joints and the shoulder girdle, allowing the right shoulder to achieve more internal rotation.

So, the effect isn’t limited to chest wall movement alone; it changes how the trunk and rib cage support the shoulder, making right shoulder internal rotation more available. The other ideas don’t fit as well because improving the left ZOA does not worsen left hip flexor tension, and it does affect shoulder motion rather than having no effect or being limited to chest wall movement.