Hip Bone Showing The Posterior Inferior Iliac Spine, Lateral View

Description

Posterior inferior iliac spine (PIIS) sits on the posterior border of the ilium, inferior to the posterior superior iliac spine and immediately superior to the superior margin of the greater sciatic notch. From this lateral perspective of the hip bone (os coxae), the PIIS reads as a blunt caudally placed projection along the dorsal iliac edge, just posterior to the auricular region that contributes to the sacroiliac joint. The adjacent iliac surface transitions anteriorly toward the acetabular region while the posterior contour drops into the greater sciatic notch, a key gateway to the greater sciatic foramen. Palpation and image-guided procedures around the sacroiliac region depend on reliably separating the PSIS from the PIIS and understanding how quickly the posterior border of the ilium turns into the greater sciatic notch. Small landmarking errors matter. For posterior pelvic approaches and for fluoroscopy or CT correlation, this fixed lateral view clarifies why the PIIS is not the joint line itself but a bony reference point near the posterior sacroiliac ligament complex, where pain generators and enthesopathic change are often discussed in sacroiliac joint dysfunction. The relationship to the superior limit of the greater sciatic notch also helps orient learners before tracing the course of the sciatic nerve and the superior gluteal neurovascular bundle as they traverse the greater sciatic foramen. Use this illustration in gross anatomy teaching of the pelvis, osteology labs, and orthopedic or pain medicine materials explaining posterior pelvic landmarks for sacroiliac joint examination, injection planning, and posterior iliac wing fracture description. It also fits radiology atlases that pair dry bone landmarks with axial and coronal pelvic imaging. Anatomical accuracy verified by SciePro's Medical Advisory Board.