The abdomen is bounded above by the ensiform cartilage and costal arches ; below by the crest of the ilium, Poupart's ligament, and the crest and symphysis pubis ; and behind by the lumbar spine. For convenience it is generally arbitrarily divided into nine sections by two vertical and two horizontal lines. The two vertical lines run upwards from the centre of Poupart's ligament on either side, while the upper horizontal line runs across at the level of the most dependent portion anteriorly of the thoracic framework (tenth costal cartilages), and the lower at the highest point of the iliac crest (about 2 inches behind the anterior superior spine). The three upper divisions so obtained consist of a middle epigastric division, and right and left hypochondriac regions ; the three central, of a middle umbilical and two lateral lumbar regions ; and the three lower of a middle hypogastric, and two lateral iliac regions.