Congenital diaphragmatic hernia is the herniation of the bowel through the diaphragm into the chest. There is usually a defect in the development of the left side of the diaphragm. It occurs in approximately 1 in 2500 newborns. The herniation occurs in the 8-10th week of gestation.

Anatomy

• The diaphragm is the main muscle of respiration (breathing)
  
• The diaphragm is a sheet of tissue composed of muscle and fascia (layer of connective tissue) that separates the thoracic (chest) cavity from the abdominal cavity
  
• It is composed of three muscles parts about the rim that lead to a central tendinous portion (Figure 1)
  
• The muscle parts are:
  
  1. The sternal portion that attaches to the breastbone area
     
  2. The costal (rib) portion that attaches along the ribs
     
  3. The lumbar portion that attaches along the back
     
• The tissue formed by the fusion of the various parts of the diaphragm is called the pleuroperitoneal membrane
  
• The are three openings in the diaphragm that allow passage of:
  
  1. The inferior vena cava
     
  2. The esophagus
     
  3. The aorta
     
• The diaphragm is covered on both sides by a membranous layer of fascia. The transversalis fascia covers the abdominal side (under side), and the endothoracic fascia covers the thoracic side (top side)
  
• The phrenic nerves (one on each side) are the only nerves that control the muscles of the diaphragm
  
• The arteries come from both sides of the diaphragm

Figure 1 - Anatomy of the diaphragm as seen from below. © C. McKee