Posterior Sacroiliac Ligament

Description

Centered on the posterior pelvis, the posterior sacroiliac ligament is rendered as interlacing short posterior sacroiliac fibers and a longer posterior band spanning from the dorsal sacrum to the posterior iliac crest adjacent to the posterior superior iliac spine. The sacrum sits medial to the ilium at the sacroiliac articulation, with the coccyx inferior and the lower lumbar vertebrae superior, clarifying the lumbosacral junction over the pelvic ring. Portions of the hip bone, including the acetabulum laterally and the proximal femoral head, frame the ligament’s relationship to load transfer from spine to lower limb. Dense collagen dominates. Posterior sacroiliac ligament anatomy matters because it is the principal restraint to counternutation and posterior gapping of the sacroiliac joint, a concept that is hard to teach without a clean posterior view. Tenderness over the posterior superior iliac spine and adjacent dorsal ligamentous complex is a frequent pain generator in suspected sacroiliac joint dysfunction, and it also becomes relevant when interpreting pain patterns after trauma to the pelvic ring or during postpartum laxity (even when the subject is male in the reference image). For posterior sacroiliac joint injection planning and radiofrequency procedures targeting the dorsal sacral lateral branches, the ligament’s topography helps explain why fluoroscopic bony landmarks do not always predict the symptomatic dorsal structures. Use this artwork in gross anatomy and musculoskeletal medicine courses to anchor the distinction between short and long posterior sacroiliac ligament components and their relationship to the iliac crest, sacral ala, and lumbosacral junction. It also fits neatly into orthopaedic, sports medicine, and pain management texts discussing posterior pelvic stability, SI joint provocation tests, and the anatomy behind dorsal SI joint interventions. Anatomical accuracy verified by SciePro's Medical Advisory Board.