Sacrum, Posterior View

Description

Centered in a posterior view, the sacrum appears as a triangular fused segment inferior to L5, with the coccyx continuing distally from the sacral apex. Along the dorsal surface, the median sacral crest runs in the midline over the fused spinous processes, flanked by the intermediate sacral crests and the paired posterior (dorsal) sacral foramina positioned lateral to the crests. Superiorly, the sacral base and alae broaden toward the sacroiliac region, while the iliac surfaces lie laterally outside the primary focus of the midline ridges. Blue intervertebral disc planes separate the lumbar vertebrae above. A posterior sacrum view matters because it matches what you palpate and what you expose in midline posterior approaches to the lumbosacral junction. The dorsal foramina transmit the dorsal rami of the sacral spinal nerves, a key teaching point when correlating posterior pelvic pain patterns and when explaining the sensory territories involved after sacral fractures or posterior pelvic ring injury. It also supports orientation for caudal epidural procedures by reinforcing the relationship between the distal sacrum, sacral hiatus region (inferior to the sacral crests, near S5), and the coccyx. Landmarks first. Use this asset in gross anatomy labs and musculoskeletal modules to contrast posterior sacral landmarks with the smoother pelvic surface, or in orthopedic and neurosurgical teaching materials covering lumbosacral fixation, sacroiliac joint anatomy, and posterior pelvic ring trauma. It also fits radiology and anatomy texts when paired with posterior projections or 3D reconstructions of the lumbosacral spine and sacrum. Anatomical accuracy verified by SciePro's Medical Advisory Board.