Detailed Presentation of the Sacroiliac Dimple

Description

Centered over the posterior pelvis, bilateral sacroiliac dimples are shown in the shallow depressions of skin and subcutaneous tissue that overlie the posterior superior iliac spines (PSIS), flanking the midline sacrum. Each dimple lies lateral to the median sacral crest and superior to the gluteal region, at the transition between the lumbar back and the posterior iliac crests. The standing neutral pose keeps left and right landmarks symmetric, making the relationship between the sacrum and the iliac bones easy to orient. Small surface markers on the lower back call attention to these palpable points. Clinically, the PSIS dimples are a practical surface landmark for locating the sacroiliac joints and guiding palpation during evaluation of suspected sacroiliac joint dysfunction, posterior pelvic pain, or inflammatory sacroiliitis. They also help frame the typical “dimples of Venus” reference used in musculoskeletal exams, where asymmetry can suggest pelvic torsion or leg-length discrepancy in conjunction with other findings. For procedural planning, that same posterior landmarking supports safe line-of-approach thinking for SI joint injections performed under fluoroscopy or ultrasound, even when the final needle placement relies on imaging confirmation. Surface anatomy matters. Use this posterior view in anatomy and physical examination courses to teach palpation of the PSIS and sacroiliac region, or in clinical skills manuals covering low back pain workups and pelvic landmarking. It also suits patient-facing education for explaining where clinicians palpate when they “check the SI joints.” Anatomical accuracy verified by SciePro's Medical Advisory Board.