Which anatomical landmark is primarily targeted in a lateral coccyx x-ray?

In a lateral coccyx x-ray, the primary anatomical landmark targeted is the sacrococcygeal joint. This joint is important because it is the articulation point between the sacrum and the coccyx, and imaging here helps in the assessment of coccygeal injuries, fractures, or other pathologies.

The sacrococcygeal joint is located at the base of the sacrum and is a critical area to visualize in lateral projections to ensure proper alignment and to capture the necessary details of the coccyx and its relationship with the sacrum. By targeting this joint, clinicians can obtain valuable information regarding the integrity and position of the coccyx, which is especially important in evaluating conditions related to trauma or pain in that region.

Understanding the relevance of the other choices provides context: the ischial tuberosities are more relevant to pelvic imaging, the inferior aspect of the sacrum is often not the focus for coccyx x-rays, and the pubic symphysis pertains to the front of the pelvis rather than the coccygeal area. Thus, targeting the sacrococcygeal joint ensures that the imaging provides the most clinically relevant information for issues pertaining to the coccyx.