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| Mediastinum | |
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| Mediastinum. The division between superior and inferior is at the sternal angle. | |
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| Mediastinum anatomy | |
| Gray's | subject #239 1090 |
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, phrenic nerve, cardiac nerve, thoracic duct, thymus, and lymph nodes of the central chest.
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Anatomy
The mediastinum lies between the right and left pleura 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 with its superior limit at the superior thoracic opening and its inferior limit at the plane from the sternal angle to the disc of T4-T5 (Plane of Ludwig);
- 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.
Role in disease
The mediastinum is frequently the site of involvement of various tumors.
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 in some cases can lead to pneumothorax, pneumoperitoneum, and pneumopericardium if left untreated. However, that does not always occur and sometimes those conditions are actually the cause, not the result, of pneumomediastinum.
These two conditions frequently accompany Boerhaave's syndrome, or spontaneous esophageal rupture.
A widened mediastinum (usually found via a chest x-ray) is a classic hallmark sign of anthrax poisoning. At this point, the disease is typically fatal.
See also
- Widened mediastinum
- Mediastinum testis (unrelated structure in the scrotum)
- Mediastinal germ cell tumor
- Mediastinitis
- Anthrax
External links
- 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"
- mediastinum at eMedicine Dictionary
- 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.
Wikipedia content modification information:
- This page was last modified on 20 August 2008, at 06:28.
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