Where should the central ray be directed for an external rotation of the shoulder?

When performing an external rotation of the shoulder, the central ray should be directed through the glenohumeral (GH) joint. This positioning is critical because it ensures that the imaging captures the joint space accurately, allowing for a clear view of the anatomical structures involved.

Targeting the GH joint is essential for diagnosing any pathologies or assessing the condition of the shoulder. This location is where the humerus articulates with the scapula, and it’s crucial for visualizing joint integrity, alignment, and any potential injuries such as dislocations, fractures, or soft tissue damage.

Positioning the central ray at the GH joint also helps in correctly positioning the humeral head and achieving the desired rotation, leading to better visualization of the rotator cuff and other soft tissue structures around the shoulder. Proper alignment during this type of imaging is necessary, as it contributes to accurate diagnostic results.