Which structures are contained within the mediastinum?

• A. The heart and great vessels
• B. The liver and gallbladder
• C. The stomach and intestines
• D. The lungs

Answer: (A)

The mediastinum is the central space in the thoracic cavity between the two lungs, and it contains the heart along with the major vessels that arise from and return blood to the heart, plus other structures like the trachea and esophagus. Because the heart and its great vessels reside there, that option correctly identifies what is contained in the mediastinum. The liver and gallbladder belong in the abdominal cavity, as do the stomach and intestines. The lungs themselves are located in the pleural cavities on either side of the mediastinum, not within it.