Aortic aperture

The aortic aperture is the route that the aorta takes on passing through the diaphragm. It is characterised by:

• sited at the level of the T12 thoracic vertebra in expiration
• formed by the median arcuate ligaments of the diaphragm
• passes behind the diaphragm as the arcuate ligaments only invest the aorta anteriorly; consequently, diaphragmatic contractions do not directly influence aortic diameter
• sited slightly to the left of the median plane
• relations:
  • anteriorly: oesophagus
  • posteriorly:
    • T12 vertebral body
    • hemi-azygous vein
  • right: inferior vena cava

other structures passing through the aortic hiatus include:

þþ thoracic duct, to the right

• azygous vein, situated more laterally on the right
• minor lymphatics