Which of the following is NOT contained within the mediastinum?

The mediastinum is the central compartment of the thoracic cavity, situated between the two lungs and surrounded by the pleura. It contains several vital structures, including the heart, trachea, aorta, esophagus, and thymus.

Lungs are located on either side of the mediastinum and are not part of it; they occupy their own space known as the pleural cavities. The presence of the lungs in these cavities is significant for their function in respiration, but they do not lie within the boundaries of the mediastinum itself. This anatomical distinction is crucial for understanding the organization of thoracic structures and the implications for various medical conditions or surgical considerations.