Abdominal Borders

3D Model

Osteological borders of the abdomen include the inferior thoracic aperture superiorly (yellow ring) that follow the contour of the subcostal margin (costal borders of the costal cartilages of ribs 8, 9 &10 (false ribs, i.e., join the costal margin of the true rib 7) and ribs 11 & 12 (floating ribs). The posterior boundary then runs posteriorly to the junction of T12/L1. The lumbar vertebrae (blue bar) form a posterior boundary vertically. Inferiorly, the iliac crest (red) running from the anterior superior iliac spines to the posterior superior iiac spines cross at the base of L5 vertebral body bounding the mid-abdominal area. The inferior bony border is provided by the pelvic brim (green ring). The pelvic brim includes the iliopectinal line as well as the sacral promontory. The peritoneum (pink) is contained within this region and forms the lower soft tissue boundary for the abdomen.