Borders, divisions and contents of the mediastinum

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The mediastinum is a compartment of the thorax located in the midline of the body, that contains most of the thoracic viscera, apart from the lungs. It extends vertically from the superior thoracic aperture to the diaphragm and is bounded laterally by the medial surfaces of the pleura.

The thoracic plane (of Ludwig), is an imaginary line extending from the sternal angle, anteriorly, to the T4-T5 intervertebral space, posteriorly. This plane divides the mediastinum into superior (above the thoracic plane) and inferior (below the thoracic plane) mediastinal divisions.

The inferior division is further subdivided into anterior, middle and posterior compartments by the pericardial sac. Structures located anterior to the pericardial sac belong to the anterior mediastinum, whereas those located posterior to pericardial sac are said to be structures of the posterior mediastinum. Those located in and around the pericardial sac belong to the middle mediastinum. 

Some structures course longitudinally both through the superior and inferior mediastinum: esophagus, azygos veins and vagus and phrenic nerves.

The video below will give you a better understanding of the boundaries, divisions and contents of the mediastinum.

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Take a closer look at the borders, divisions and contents of the mediastinum from a lateral perspective.

Now explore the associated structures of the mediastinum from an anterior view.

Summary