57 The Mediastinum

What is the Mediastinum?:

You can think about the mediastinum as the region of the chest between the cavities for the right and left lungs that houses the heart, the root of all major blood vessels, and many other key structures. The mediastinum is divided into the superior and inferior mediastinum. The inferior mediastinum is further divided into the superior, anterior, middle, and posterior regions.

The superior region contains the arch of the aorta as it leaves the heart and branches out. The trachea is also present in the superior region, just in front of the esophagus. A key immune organ, known as the thymus, is the most anterior structure in the superior mediastinum. The middle region of the inferior mediastinum houses the heart and the beginning of the aorta. It also houses the pulmonary trunk which contains the pulmonary arteries and phrenic nerves, which innervate the diaphragm. The inferior region is composed of the descending aorta, which brings oxygen rich blood to the lower portion of the body. The esophagus is also situated in this region as it continues to the stomach, and the vagus nerve.