Right lateral region of abdomen

The right lateral region of the abdomen is anatomically defined as the area on the right side of the abdominal wall, bounded superiorly by the lower ribs and costal cartilages, inferiorly by the iliac crest and inguinal ligament, anteriorly by the rectus abdominis muscle, and posteriorly by the iliocostalis lumborum and quadratus lumborum muscles. This region contains the lateral abdominal wall muscles: the transversus abdominis, internal oblique, and external oblique, which span between these boundaries. 

Clinically, the right lateral region is often referred to as the right lumbar region in surface anatomy, situated between the right hypochondriac (above) and right iliac (below) regions. It is lateral to the umbilical region and corresponds to the area overlying the ascending colon and portions of the small intestine.