The superior mediastinum is located behind the manubrium of the sternum and anteriorly to the bodies of the first four thoracic vertebrae. 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 - a transverse plane passing from the sternal angle to the intervertebral disc between the fourth and fifth vertebrae

• Laterally: mediastinal part of the parietal pleura on each side

• Anterior: manubrium of the sternum

• Posterior: T1-T4 vertebrae

The superior mediastinum contains the: esophagus, trachea, thymus, phrenic nerve, vagus nerve, left recurrent laryngeal nerve; superior vena cava, brachiocephalic veins, aortic arch, and thoracic duct.