Mediastinum

Mediastinum is a movable partition of the thorax that extends superiorly to the thoracic outlet in the root of the neck and inferiorly to the diaphragm. Anteriorly it extends to the sternum and posteriorly to the vertebral column. It contains the following structures:

  • Thymus
  • Heart and large blood vessels
  • Trachea
  • Esophagus
  • Thoracic duct
  • Lymph nodes
  • Vagus and phrenic nerves
  • Sympathetic trunk

Divisions of mediastinum:

Mediatinum is divided into two partitions, just for the purpose of description, by an imaginary plane that extends from the sterna angle anteriorly to the body of fourth thoracic vertebra posteriorly. The two partitions are known as superior mediastinum and Inferior mediastinum. The inferior mediastinum is further divided into three partition, again just for the purpose of description. These three partitions are anterior mediastinum, posterior mediastinum and middle mediastinum.

  • Anterior mediastinum: It is the space between the pericardium and the sternum.
  • Posterior mediastinum: It lies between the pericardium and the vertebral column
  • Middle mediastinum: It contains pericardium and heart

To remember the structures of the superior and inferior mediastinum in order, follow the description given below.

Superior mediastinum:

  • Thymus
  • Large veins
  • Large arteries
  • Trachea
  • Esophagus and thoracic duct
  • Sympathetic trunks

Inferior mediastinum:

  • Thymus
  • Heart within the pericardium with phrenic nerves on each side
  • Esophagus and thoracic duct
  • Descending aorta
  • Sympathetic trunks