Mediastinum

From Wikipedia, the free encyclopedia

Mediastinum
Mediastinum. The division between superior and inferior is at the sternal angle.
Gray's	subject #239 1090
Dorlands/Elsevier	m_06/12518945

The mediastinum is a non-delineated group of structures in the thorax (chest), surrounded by loose connective tissue. It is the central compartment of the thoracic cavity. It contains the heart, the great vessels of the heart, esophagus, trachea, thymus, and lymph nodes of the central chest.

Contents 1 Anatomy 2 Role in disease 3 See also 4 External links

[edit] Anatomy

The mediastinum lies between the right and left pleuræ in and near the median sagittal plane of the chest. It extends from the sternum in front to the vertebral column behind, and contains all the thoracic viscera except the lungs. It may be divided for purposes of description into two parts:

• an upper portion, above the upper level of the pericardium, which is named the superior mediastinum;
• and a lower portion, below the upper level of the pericardium. This lower portion is again subdivided into three parts, viz.:
  • that in front of the pericardium, the anterior mediastinum;
  • that containing the pericardium and its contents, the middle mediastinum;
  • and that behind the pericardium, the posterior mediastinum.

It is surrounded by the chest wall anteriorly, the lungs laterally and the spine posteriorly. It is continuous with the loose connective tissue of the neck, and extends inferiorly onto the diaphragm.

Note that clinical radiologists and anatomists categorize the mediastinum in slightly different ways.

[edit] Role in disease

Main article: anterior mediastinal mass

The mediastinum is frequently the site of involvement of various cancers. Masses in the anterior portion of the mediastinum can include thymoma, lymphoma, germ cell tumor and teratoma. Lung cancer typically spreads to the lymph nodes in the mediastinum.

Mediastinitis is inflammation of the tissues in the mediastinum, usually bacterial and due to rupture of organs in the mediastinum. As the infection can progress very quickly, this is a serious condition.

Pneumomediastinum is the presence of air in the mediastinum, which can lead to pneumothorax, pneumoperitoneum, and pneumopericardium if left untreated in some cases. However, that does not always happen and sometimes those conditions actually are the cause, not the result, of pneumomediastinum.

These two conditions frequently accompany Boerhaave's syndrome, or spontaneous esophageal rupture.

[edit] See also

• Widened mediastinum
• Mediastinum testis (unrelated structure in the scrotum)
• Mediastinal germ cell tumor

[edit] External links

• GPnotebook 1691353147
• SUNY Figs 21:01-03 - "Divisions of the mediastinum."
• SUNY Figs 21:02-03 - "The anatomical divisions of the inferior mediastinum."
• Norman/Georgetown thoraxlesson3 - "Subdivisions of the Thoracic Cavity"
• Dictionary at eMedicine mediastinum
• Anatomy at MUN thorax/media

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.