Anatomical Structure And Location Of The Posterior Sacral Foramina

Description

Posterior sacral foramina punctuate the dorsal surface of the sacrum in four paired levels, aligned vertically on either side of the median sacral crest. Each foramen sits lateral to the fused sacral spinous processes and medial to the intermediate sacral crests, which mark the line of fused articular processes. The openings correspond to the dorsal sacral foramina of S1 through S4, positioned inferior to the broad sacral alae and superior to the sacral hiatus near the apex. Bony relief is prominent. Clinically, these foramina map the exit points of the posterior (dorsal) rami of the sacral spinal nerves, a detail that matters when localizing pain generators in posterior pelvic and low back syndromes. Palpation and fluoroscopic targeting for sacroiliac region procedures often reference the dorsal sacral foramina, since lateral branch blocks and radiofrequency denervation for sacroiliac joint pain commonly target the posterior sacral network in the vicinity of the S1 to S3 foraminal levels. The posterior viewpoint clarifies the relationships between the foramina, the median and intermediate crests, and the inferomedial sacral hiatus, which helps distinguish true foraminal openings from surface pits or fracture irregularities on the dorsal sacrum. Use this illustration in gross anatomy labs and osteology teaching to anchor orientation of the sacrum within the pelvis, and in pain medicine or spine publications discussing sacroiliac joint interventions, posterior sacral nerve anatomy, or dorsal sacral fractures. It also supports patient education graphics for posterior pelvic pain where precise bony landmarks reduce ambiguity. Anatomical accuracy verified by SciePro's Medical Advisory Board.