Vena caval foramen

The vena caval foramen is the diaphragmatic aperture through which the vena cava passes. It has the following characteristics:

• in expiration, situated at the level of the lower border of T8 vertebra which approximates the 6th costal cartilage
• the most superior of all the large diaphragmatic apertures
• passes through the tendinous part of the diaphragm a few centrimetres anterior to the vertebral body and to the right of the median plane
• the vena cava is firmly attached to the sides of the foramen; consequently, on contraction of the diaphragm, the aperture descends and increases in diameter. This has the effect of increasing vena caval diameter and facilitating thoracic venous return.
• other structures that may pass through the aperture include:
  • right phrenic nerve
  • ascending lymphatics
  • infrequently, the right hepatic vein