Medial Part Of The Sacrum, Superior View

Description

Sacral base anatomy dominates this superior view of the medial sacrum, centered on the broad, oval superior surface of the S1 vertebral body at the pelvic brim. Posterior to the body, the opening of the sacral canal is visible in the midline, flanked by the paired superior articular processes that face posteromedially to meet the inferior articular processes of L5 at the lumbosacral junction. The sacral promontory forms the anterior margin of the base and projects anteriosuperiorly, while the median contour around it defines the central axis of the pelvic inlet. Fixed orientation keeps the midline relationships unambiguous. Clinical teaching often hinges on this exact topography: the S1 body and sacral promontory are palpation and imaging landmarks for assessing pelvic incidence and sagittal balance, and they help frame discussions of L5–S1 disc degeneration and spondylolisthesis. Obstetrics also returns to the promontory when defining the obstetric conjugate and evaluating a contracted pelvic inlet. Small but consequential details. The lighting and bony surface treatment support recognition of the articular surfaces and the transition from vertebral body to sacral canal without distracting soft tissues. Use this illustration in gross anatomy and musculoskeletal courses when introducing the axial skeleton at the lumbosacral transition, or in orthopedic and spine texts discussing L5–S1 alignment, sacral morphology, and operative corridors near the sacral promontory. It also fits radiology teaching files that correlate pelvic inlet landmarks on CT or MRI with osseous anatomy. Anatomical accuracy verified by SciePro's Medical Advisory Board.