The superior mediastinum is located behind the manubrium of the sternum and anteriorly to the bodies of the first four thoracic vertebrae (T1 - T4). It is continuous with the neck above and the inferior mediastinum below. 

The boundaries of the superior mediastinum are considered the following:

• Superiorly - superior thoracic aperture;
• Inferiorly - tranverse thoracic plane;
• Laterally - mediastinal part of the parietal pleura on each side;
• Anteriorly - manubrium of the sternum;
• Posteriorly - thoracic vertebrae T1 - T4.

The superior mediastinum contains the following structures: esophagus, trachea, thymus, several nerves (phrenic nerve, vagus nerve (CN X), left recurrent laryngeal nerve), superior vena cava, brachiocephalic veins, aortic arch and its branches and thoracic duct.