As we know, the mediastinum is divided into the superior mediastinum and the inferior mediastinum.

The superior mediastinum is separated from the inferior mediastinum by the transverse thoracic plane, which is a horizontal plane that extends from the sternal angle anteriorly and the junction of T4 and T5 posteriorly, an important anatomical landmark representing the bifurcation of the trachea and the beginning and end of the arch of the aorta.

The inferior mediastinum lies between the transverse thoracic plane superiorly, and the diaphragm inferiorly, and is further subdivided by the pericardium into anterior, middle and posterior parts.

So first, let’s look at the posterior mediastinum.

It is located anterior to the T5 through T12 vertebrae, posterior to the pericardium and diaphragm, inferior to the transverse thoracic plane and between the parietal pleura of the lungs.

The posterior mediastinum contains the thoracic aorta, thoracic duct and lymphatic trunks, posterior mediastinal lymph nodes, azygos and hemiazygos veins, the esophagus and the esophageal nerve plexus.

The thoracic aorta continues the aortic arch and it begins on the left side of the inferior border of the body of T4, moving downwards in the posterior mediastinum on the left side of T5 through T12 vertebrae.

On its way down, the thoracic aorta is close to the median plane and moves the esophagus towards the right.

The thoracic aorta lies posterior to the root of the left lung, pericardium and esophagus and is surrounded by the thoracic aortic plexus.

Anterior to the inferior border of the T12 vertebra it continues on as the abdominal aorta and enters the abdomen through the aortic hiatus in the diaphragm.