Anterior Abdominal Wall

• Is also divided by vertical and horizontal planes through the umbilicus into four quadrants: right and left upper quadrants and right and left lower quadrants. The umbilicus lies at the level of the intervertebral disk between the third and fourth lumbar vertebrae. Its region is innervated by the tenth thoracic nerve.

• Is divided topographically by two transverse and two longitudinal planes into nine regions: right and left hypochondriac, epigastric , right and left lumbar, umbilical , right and left inguinal (iliac) , and hypogastric (pubic).