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The mediastinum (from Medieval Latin ''mediastinus'', "midway"〔(Mediastinum dictionary definition )〕) is the central compartment of the thoracic cavity surrounded by loose connective tissue, as an undelineated region that contains a group of structures within the thorax. The mediastinum contains the heart and its vessels, the esophagus, trachea, phrenic and cardiac nerves, the thoracic duct, thymus and lymph nodes of the central chest. ==Structure== The mediastinum lies within the thorax and is enclosed on the right and left by pleurae. It is surrounded by the chest wall in front, the lungs to the sides and the spine at the back. It extends from the sternum in front to the vertebral column behind, and contains all the organs of the thorax except the lungs. It is continuous with the loose connective tissue of the neck. The mediastinum can be divided into an upper (or superior) and lower (or inferior) part: * The superior mediastinum starts at the superior thoracic aperture and ends at the thoracic plane. * The thoracic plane separates the superior and inferior mediastinum. It is a plane at the level of the sternal angle, and the intervertebral disc of T4-T5.〔(Thoracic Wall, Pleura, and Pericardium - Dissector Answers )〕〔(Untitled Document )〕〔(UAMS Department of Anatomy - Topographical Anatomy - Thorax )〕 * The inferior mediastinum from this level to the diaphragm. This lower part is subdivided into three regions, all relative to the pericardium - the anterior mediasteinum being in front of the pericardium, the ''middle mediastinum'' contains the pericardium and its contents, and the ''posterior mediastinum'' being behind the pericardium. Anatomists, surgeons, and clinical radiologists compartmentalize the mediastinum differently. For instance, in the radiological scheme of Felson, there are only three compartments (anterior, middle, and posterior), and the heart is part of the anterior mediastinum. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「mediastinum」の詳細全文を読む スポンサード リンク
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