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: