Which structures are enclosed by the hilum of the lung?

• A. The heart and esophagus
• B. The main bronchus, pulmonary arteries and veins, bronchial vessels and nerves
• C. The thoracic duct
• D. The apex of the pleura

Answer: (B)

The hilum is the lung’s root, the doorway where structures connecting the lung to the mediastinum enter and exit. It encloses the main bronchus along with the pulmonary arteries and veins, and also carries the bronchial vessels and nerves that accompany these airways and blood vessels. That bundle of structures forms the core of what enters the lung, which is why this option is the best choice.

The other structures don’t pass through the hilum. The heart and esophagus sit in the mediastinum but are not part of the lung’s hilum. The thoracic duct runs in the posterior mediastinum and does not pass through the hilum. The apex of the pleura is the top extension of the pleural sac above the hilum, not enclosed by it.