Sacroiliac Dimple, Gross Anatomy

Description

Centered on the posterior lumbosacral region, the paired sacroiliac dimples (foveae lumbales laterales) sit symmetrically over the posterior superior iliac spines, just lateral to the midline and superior to the upper sacrum. Superficial skin indentations correspond to the underlying iliac crest contour and the dense attachments of thoracolumbar fascia over the erector spinae and multifidus, with the intergluteal cleft descending inferiorly toward the coccygeal level. Blue surface markers emphasize the right and left PSIS points on an adult Black male torso in an anatomic standing posture. These are palpable landmarks. For clinicians, the sacroiliac dimples give a fast, reliable surface cue for locating the posterior pelvic ring: the PSIS anchors palpation of the sacroiliac joint line, guides posterior SI joint injection trajectories under fluoroscopy or ultrasound, and helps orient posterior approaches during sacroiliac fusion planning. Pain localized just inferomedial to the PSIS (the Fortin area) is often discussed in suspected sacroiliac joint dysfunction, and this view supports teaching the distinction between SI pain patterns and more lateral posterior hip or gluteal tendinopathy. Surface anatomy matters when imaging is not immediately available. Use this asset in gross anatomy and musculoskeletal medicine courses to teach posterior trunk landmarks, or in procedural education materials covering palpation, landmark-guided examinations, and SI joint interventions. It also fits clinical handouts and atlases addressing low back pain localization, with a realistic skin-and-form presentation appropriate for patient-facing contexts. Anatomical accuracy verified by SciePro's Medical Advisory Board.