embryology

Last reviewed 01/2018

The diaphragm is derived from four embryological sources which fuse in the neck and then descend:

• septum transversum; eventually forms the central diaphragmatic tendon
• pleuroperitoneal membranes
• the dorsal mesenteric mesoderm:
• eventually forms the median section of the diaphragm
• includes the crura and the mesentery around the oesophagus and vena cava
• the dorsal body wall mesoderm:
• relative enlargement of the lungs cleaves the inside surface of the body wall
• the innermost layer of this division forms the peripheral margins of the eventual diaphragm
• mesenchyme from the septum transversum migrates into this area to form skeletal muscle:
• myoblasts are derived from C3-5
• in descent, they bring their nerve supply

Failure of tissue fusion of any of the four masses can lead to potential spaces that are traversed to produce congenital diaphragmatic hernia e.g.:

• Bochdalek's foramen leading to Bochdalek's hernia
• Morgagni's foramen leading to Morgagni's hernia