Where it is
Separates the thoracic cavity from the abdominal cavity. It attaches to the lower ribs, the sternum and the lumbar vertebrae, and has openings for the esophagus, aorta and inferior vena cava.
What it does
When it contracts, the dome flattens and moves down, enlarging the chest so air flows into the lungs. When it relaxes, it rises and air flows out. It is innervated by the phrenic nerve (C3, C4, C5).
Clinical relevance
- "C3, 4, 5 keeps the diaphragm alive": a spinal cord injury at or above C4 can stop spontaneous breathing.
- A hiatal hernia occurs when part of the stomach slides up through the esophageal opening.
- Abdominal surgery and pain limit diaphragm movement, raising the risk of atelectasis.
Nursing focus
- Teach diaphragmatic breathing and incentive spirometry after surgery.
- Position clients with dyspnea upright (high Fowler's) so the diaphragm can descend.