part_of part of part of located in trunk coelemic cavity lumen mesenchyme septum transversum The cranial part of the septum transversum gives rise to the central tendon of the diaphragm and is the origin of the myoblasts that invade the pleuroperitoneal folds resulting in the formation of the muscular diaphragm. The caudal part of the septum transversum is invaded by the hepatic diverticulum which divides within it to form the liver and thus gives rise to the ventral mesentery of the foregut.