Diaphragm Openings (Hiatuses)
The diaphragm is the primary muscle of respiration. It contains three major openings (hiatuses) that allow structures to pass between the thorax and the abdomen.
The Three Major Hiatuses
| Hiatus | Vertebral Level | Key Contents |
|---|---|---|
| Caval Hiatus | T8 | Inferior Vena Cava (IVC), right phrenic nerve. |
| Esophageal Hiatus | T10 | Esophagus, anterior and posterior vagal trunks. |
| Aortic Hiatus | T12 | Descending aorta, thoracic duct, azygos vein. |
High-Yield Exam Pearl:
Remember the vertebral levels by the number of letters in the keyword:
- Vena Cava (8 letters) = T8
- Oesophagus (10 letters) = T10
- Aortic (12 letters) = T12
The aortic hiatus is not technically “in” the diaphragm (it is an opening *behind* the median arcuate ligament), which is why the aorta is not compressed during diaphragmatic contraction.