The diaphragm develops from four main mesodermal components: the septum transversum, pleuroperitoneal membranes, dorsal mesentery of the esophagus, and body wall mesoderm. The septum transversum forms the central tendon and openings for the esophagus and vena cava. The pleuroperitoneal membranes form the small peripheral parts, while the dorsal mesentery of the esophagus forms the right and left crus. Congenital defects in the diaphragm can result in hernias if parts fail to develop, such as posterolateral or posterior hernias.