Caval foramen

The caval foramen is an opening in the diaphragm that is located within the right leaflet of the central tendon of the diaphragm at the vertebral level T8.

The most important structure passing through the caval foramen is the inferior vena cava (IVC), which carries deoxygenated blood from the lower body to the right atrium of the heart. In addition to the IVC, the terminal branches of the right phrenic nerve and accompanying lymphatic vessels also pass through this opening.

Because the caval foramen lies within the central tendon, it widens during inspiration as the diaphragm contracts and descends. This facilitates venous return to the heart by reducing resistance to blood flow within the inferior vena cava.

Clinically, the caval foramen is important because compression or obstruction of the inferior vena cava can impair venous return and affect cardiac output.