Hip Bone In Medial View Showing The Posterior Superior Iliac Spine

Description

Posterior superior iliac spine (PSIS) anchors the posteromedial margin of the ilium at the posterior end of the iliac crest, sitting superior to the auricular surface that articulates with the sacrum at the sacroiliac joint. From this medial perspective, the iliac fossa occupies the broad anterior-medial concavity, while the arcuate line (linea terminalis) forms a distinct ridge inferiorly as it courses toward the superior pubic ramus. Immediately inferior to the PSIS, the posterior inferior iliac spine (PIIS) and the superior aspect of the greater sciatic notch define the transition from the iliac blade to the posterior border of the hip bone. Bony relief is the point. Clinically, PSIS remains one of the most relied-upon palpable landmarks for orienting the posterior pelvis, commonly used to estimate the level of S2 and to guide surface marking for posterior sacroiliac joint pain procedures, including fluoroscopy or ultrasound correlation when targeting periarticular ligaments rather than the true synovial portion of the joint. The medial emphasis brings the auricular surface and iliac tuberosity into the same frame, which helps clarify why tenderness or enthesopathy around the posterior sacroiliac ligaments can localize near PSIS while intra-articular pathology tracks along the ear-shaped articular surface. In pelvic ring trauma teaching, this fixed relationship also supports explanation of posterior pelvic stability and why disruptions near the sacroiliac complex have high biomechanical consequence. Orthopedic and sports medicine texts can pair this illustration with posterior pelvic palpation, sacroiliac joint injection technique discussions, and interpretation of CT or MRI findings at the iliac side of the sacroiliac joint. Anatomy and osteology courses will also find it useful for identifying the iliac crest, PSIS, arcuate line, and greater sciatic notch in a single reference image. Anatomical accuracy verified by SciePro's Medical Advisory Board.