Final answer:
The sacral nodes drain lymphatic fluid from the sacral region, which flows into the left common iliac vein and then into the inferior vena cava. The middle sacral vein also drains venous blood from this area into the left common iliac vein.
Step-by-step explanation:
The sacral nodes drain lymphatic fluid from the sacral region of the body. This fluid eventually flows into the left common iliac vein, which is formed by the union of the external and internal iliac veins near the inferior portion of the sacroiliac joint. The left common iliac vein then drains into the inferior vena cava at the level of L5.
In terms of venous blood drainage, the middle sacral vein specifically drains blood from the sacral region and also leads to the left common iliac vein. Additionally, the deeper parts of the body drain into various ducts and trunks, such as the lumbar veins and thoracic duct, that ultimately lead into the major venous system, like the subclavian veins and superior vena cava.