To bring the coracoacromial ligament closer to the surface, what action will roll the humeral head anteriorly, pressing the ligament forward?

The correct action that rolls the humeral head anteriorly, bringing the coracoacromial ligament closer to the surface, is extension. During shoulder extension, the humeral head moves backward within the glenoid cavity. This motion allows the anterior aspect of the humeral head to roll forward, effectively pressing the coracoacromial ligament toward the anterior surface.

In contrast, flexion would typically cause the humeral head to roll posteriorly or upward, which does not bring the ligament closer to the surface. Circumduction involves a combination of movements (flexion, extension, abduction, and adduction) and does not specifically isolate the movement needed to achieve anterior rolling of the humeral head. Abduction raises the arm laterally but primarily moves the humeral head upwards, in a manner that does not significantly affect the positioning of the ligament. Understanding shoulder biomechanics helps clarify why extension is the most appropriate action for this specific scenario.