Superior Mediastinum

Boundaries

Boundaries of the superior mediastinum (1)are:
  • anterior - manubrium of the sternum
  • posterior - anterior surface of bodies of vertebrae T1 through T4
  • superior - plane of the thoracic inlet
  • inferior - plane of the sternal angle
  • lateral - mediastinal pleura

Contents of the Superior Mediastinum

If it helps to remember what is in the superior mediastinum, you can visualize the contents in planes from anterior to posterior:

This is how we will approach its study.
This image shows the structures of the superior mediastinum in tact. Then we will start from the anterior boundary and work our way through the superior mediastinum from anterior to posterior.
With the thorax in tact, the first thing you see when you get ready to study the superior mediastinum is the manubrium of the sternum and the cartilage of the first rib. These structures make up the anterior boundary.
The first plane is the glandular plane. The gland is what is left of the thymus. It consists of two lobes and is mainly fat in the adult with small islets of active thymic cells scattered throughout.
The second plane is the venous plane and consists of the:
  • left brachiocephalic vein
  • right brachiocephalic vein
  • superior vena cava
  • arch of the azygos vein
The third plane is the arterial-nervous plane and consists of the:
  • aortic arch and its branches
    • brachiocephalic artery
    • left common carotid artery
    • left subclavian artery
  • nerves include the:
    • left and right vagus nerves
    • left and right phrenic nerves
The fourth plane is the visceral plane and includes the:
  • trachea
  • esophagus
  • left recurrent laryngeal nerve
Trachea
Esophagus
The fifth plane is the lymphatic plane and consists of the:
  • thoracic duct


Posterior Mediastinum   Summary of Thorax Items


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