Fusion of the various components of the diaphragm may fail, and hernias may occur through the failed points of fusion (Fig. 4.146). The commonest sites are: between the xiphoid process and the costal margins on the right (Morgagni’s hernia), and through an opening on the left when the pleuroperitoneal membrane fails to close the pericardioperitoneal canal (Bochdalek’s hernia).