When taking lateral flexion images of the cervical spine, where should the central ray (CR) be directed?

In lateral flexion imaging of the cervical spine, the central ray (CR) is typically directed at the level of C4. This positioning ensures that the critical cervical vertebrae, particularly those related to the motion of the head and neck, are well visualized. C4 corresponds to the mid-cervical region, which is key for assessing the range of motion and alignment of the cervical spine during lateral flexion.

The choice of C4 for the CR placement takes into account the anatomical landmarks and the need to capture the greatest range of motion while minimizing distortion in the images.

C4 is situated between the cervical spine's upper and lower segments, providing a balanced view during imaging.

While other cervical vertebrae like C3, C5, and C6 are important, they are not the standard reference point for lateral flexion images. C3 is too high, potentially excluding important visual cues. C5 and C6 are located lower in the cervical region, which may not encompass the necessary structures for a thorough lateral flexion assessment at C4. Therefore, targeting C4 provides the optimal visualization for evaluating lateral flexion in the cervical spine.