Lateral region of abdomen

The lateral region of the abdomen refers to the area of the abdominal wall that is situated on the sides of the abdomen. The right and left lateral region of abdomen are separated medialy by the umbilical region and bounbded superiorly by the right and left hypochondriac region, and inferiorly by the inguinal regions.

This region is anatomically defined by the presence of three primary muscles: the transversus abdominis, internal oblique, and external oblique muscles. These muscles span the abdominal cavity between the iliocostalis lumborum and quadratus lumborum posteriorly and the rectus abdominis anteriorly. The lateral abdominal wall is bounded superiorly by the lower ribs and costal cartilages and inferiorly by the iliac crest and inguinal ligament.

Some sources called these regions the right and left lumbar regions (containing respectively on right the gallbladder, the right kidney, part of the liver, and the ascending colon and on the left the descending colon, the left kidney, and part of the spleen) but this terminology is confusing with the lumbar region (of back) listed in the terminologia anatomica.