Which of the following is the correct SCP while palpating an anterior glide on the ilium?

When palpating for an anterior glide on the ilium, the correct surface landmark to consider is the PSIS (Posterior Superior Iliac Spine). The PSIS provides a bony reference point that is crucial when assessing the position and mobility of the ilium in relation to the sacrum.

During an anterior glide assessment, the clinician typically observes movement about the sacroiliac joint, which experiences specific motions indicated by the position of the PSIS. The PSIS acts as an anchor for analyzing the ilium's movement; when the ilium moves anteriorly, the PSIS will facilitate the clinician's understanding of the kinematics happening at the joint.

Using landmarks such as the ASIS (Anterior Superior Iliac Spine) or midline sacral base might not provide as accurate or relevant information for assessing posterior-to-anterior or anterior-to-posterior displacements at the ilium during a glide. Additionally, the bilateral mammillary processes relate to lumbar vertebrae and do not pertain directly to the ilium's motion in the context of a sacroiliac assessment.

Thus, the PSIS serves as the most appropriate and practical landmark for this specific palpation technique, making it the correct choice in this scenario.