How does blood drain from the upper part of the esophagus?

The upper part of the esophagus primarily drains blood through the inferior thyroid veins. These veins are responsible for collecting venous blood from the upper esophagus, particularly in the cervical region of the esophagus. They then transport this blood to the brachiocephalic veins, which ultimately drain into the superior vena cava.

While the azygos vein and the superior vena cava are indeed significant vessels in the overall drainage of the thoracic region and other parts of the body, they are not the primary drainage routes for the upper esophagus. The portal vein is not involved in draining the esophagus as it is primarily associated with the intestines and spleen, carrying blood to the liver. Therefore, considering the specific anatomy and venous drainage patterns, the inferior thyroid veins are the main vessels that collect blood from the upper portion of the esophagus.