16- Structuring of the Venous System 1_ The Cardinal Veins

The structuring of the human venous system is based on three main venous systems: the neurocranial system, the viscerocranial system, and the internal system. Each of these systems originates from embryological precursors, notably the cardinal, vitelline, and umbilical veins. The cardinal veins, which divide into superior and inferior cardinal veins, play a fundamental role in the development of the venous system, forming the venous sinus and contributing to the formation of the inferior vena cava through anastomoses with other venous structures.

The development of the cardinal veins is accompanied by the formation of subcardinal and supracardinal veins, which emerge from the cardinal network. These subcardinal veins participate in the formation of the inferior vena cava and other important venous structures, while the supracardinal veins ensure thoracic and abdominal drainage. As these systems develop, remnants of the cardinal veins persist, notably the azygos system, which plays a crucial role in thoracic drainage. The process of venous development is characterized by budding and regression movements, illustrating the complexity and adaptability of the human vascular system.