A Posterior Perspective of the Sacroiliac Dimple in a Black Male

Description

Centered on the lower posterior trunk, the paired sacroiliac dimples align just medial and slightly inferior to the posterior superior iliac spines, flanking the midline over the sacrum. Superiorly, the contour transitions into the lumbar region where the erector spinae columns rise on either side of the spinous processes beneath the thoracolumbar fascia, with the trapezius and latissimus dorsi forming broader superficial planes. Laterally, the iliac crests define the superior border of the pelvis, while the dimples sit posterior and medial relative to the iliac spines as reliable surface landmarks. Two blue markers highlight a mid-thoracic reference point and a low lumbar to sacral target area. Sacroiliac dimples matter because they anchor surface anatomy to the bony pelvis in a way that stays readable even when body habitus changes, helping you triangulate the level of the PSIS and the approximate S2 segment. They also provide a practical entry point for teaching palpation before fluoroscopy or ultrasound, since SI joint pain, sacroiliitis, and posterior pelvic ring injuries are often discussed alongside landmark-guided examination and referral patterns into the buttock and posterior thigh. Surface landmarks are not the joint line. That distinction is where trainees often stumble. Use this posterior perspective in gross anatomy labs, physical examination and musculoskeletal medicine courses, and in clinical skills content covering pelvic landmark palpation, SI joint provocation tests, and image-guided injection planning. It also fits well in patient-facing educational materials where culturally accurate skin tone and recognizable posterior pelvic landmarks improve communication around low back and sacroiliac pain. Anatomical accuracy verified by SciePro's Medical Advisory Board.