Superior Lumbar Triangle

Description

Posterior surface anatomy of the lower back is presented with bilateral highlighting of the superior lumbar triangle (Grynfeltt-Lesshaft triangle) on either side of the lumbar region. The triangle lies inferior to the 12th rib and adjacent costal margin, lateral to the erector spinae mass, and superior to the iliac crest, occupying the posterolateral abdominal wall deep to the latissimus dorsi. In anatomical terms, it sits lateral to the spinous processes and medial to the flank, with the left and right triangles mirrored across the vertebral midline. Arms are slightly abducted with the forearms supinated, keeping the posterior trunk landmarks unobstructed. Clinically, the superior lumbar triangle is a recognized site of primary lumbar hernia, where retroperitoneal fat or colon may protrude through the posterior abdominal wall, often presenting as a flank bulge that becomes more apparent with Valsalva. Surgical planning depends on knowing the triangle’s borders: 12th rib superiorly, internal oblique laterally, and quadratus lumborum medially, with a relatively weak fascial floor near the transversalis fascia. This view keeps the relationship to the rib, paraspinal contour, and iliac crest readable. A clear landmark. Use this rendering for gross anatomy and surface anatomy teaching on the dorsal trunk, for radiology correlation when localizing posterolateral abdominal wall defects on CT, or for operative education discussing open or laparoscopic lumbar hernia repair and port placement relative to the 12th rib and iliac crest. Anatomical accuracy verified by SciePro's Medical Advisory Board.