In the posterior mediastinum, the thoracic duct lies between which vessels?

• A. Esophagus and trachea
• B. Aorta and azygos vein
• C. Vagus nerve and thoracic duct
• D. Pulmonary trunk and superior vena cava

Answer: (B)

The thoracic duct in the posterior mediastinum runs upward between the aorta on the left and the azygos vein on the right, just posterior to the esophagus. This location persists as it ascends from the abdomen, crossing to the left around the level of T5–T6 before draining into the left venous angle. Among the options, this between-vessels relationship is the best description.

Other choices mix up structures: the esophagus and trachea are organs, not vessels; the vagus nerve is a nerve, not a vessel; and the pulmonary trunk and superior vena cava are major vessels in different parts of the mediastinum and do not describe the duct’s typical course.