Posterior Superior Iliac Spine Of The Hip Bone

Description

Posterior superior iliac spine (PSIS) anchors the posterior end of the iliac crest as it turns medially toward the sacroiliac region. The bony prominence sits superior to the greater sciatic notch and lateral to the dorsal surface of the sacrum, forming a palpable corner of the posterior pelvic brim. From a posterior, slightly oblique perspective, the PSIS is seen as a pointed projection continuous with the posterior border of the ilium, with the nearby iliac crest sweeping laterally and the sacroiliac articular area lying immediately anteromedial. Edges are crisp. Clinically, the PSIS matters because it is the bedside landmark most often used to localize the sacroiliac joint and the S2 level, and it guides palpation in suspected sacroiliac pain, pelvic torsion, and assessment of posterior pelvic alignment in low back pain pathways. Its relationship to the posterior sacroiliac ligaments and adjacent fascia (including the thoracolumbar fascia attachment along the posterior iliac crest) also explains why tenderness here can reflect ligamentous strain rather than intra-articular pathology. The fixed lighting and surface relief help separate the PSIS from the adjacent posterior inferior iliac spine and from irregularities of the iliac tuberosity that can confuse less experienced palpation. Use this illustration in gross anatomy and osteology teaching to orient students to pelvic girdle landmarks, in orthopedic and sports medicine materials discussing sacroiliac joint provocation tests and injection targeting, or in manual therapy references that standardize PSIS palpation points. It also suits atlas-style labeling for posterior pelvis anatomy and ligament attachment discussions in musculoskeletal modules. Anatomical accuracy verified by SciePro's Medical Advisory Board.