Which axis does the humerus rotate around during shoulder abduction?

During shoulder abduction, the humerus primarily rotates around the Z axis. In biomechanical terms, the Z axis runs perpendicular to the plane of movement, which, in the case of shoulder abduction, is the sagittal plane. When the arm moves away from the body, the humerus glides upward, and this movement can be visualized as a rotation around the Z axis.

In anatomical terms, when the arm is raised in abduction, it primarily involves the movement of the shoulder joint where the humerus elevates and externally rotates. This motion allows for the arm to move laterally away from the trunk while maintaining a stable position, demonstrating the significance of the Z axis in this particular movement. The orientation of the Z axis aligns with the direction of force and movement during shoulder abduction, making it a fundamental aspect of understanding shoulder mechanics.

This understanding of the Z axis and its relationship with shoulder abduction is crucial for the assessment and rehabilitation of shoulder injuries, as well as for designing effective strength training and flexibility programs aimed at improving shoulder function.