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| The [[mediastinum]] is a non-delineated group of structures in the [[Thorax|thorax (chest)]], surrounded by [[loose connective tissue]]. It is the central [[Compartment (anatomy)|compartment]] of the [[thoracic cavity]]. It contains the [[heart]], the [[great vessels]] of the [[heart]], [[esophagus]], [[trachea]], [[thymus]], and [[Lymph node|lymph nodes]] of the [[Mediastinum|central chest]]. A wide variety of [[Mediastinal mass causes|diseases]] involving these organs can present as a mediastinal mass or widening of the [[mediastinum]] on [[imaging studies]]. Mediastinal widening is diagnosed by the [[mediastinum]] measuring greater than 8 cm in width on [[Chest x-ray|PA chest x-ray]]. The mediastinal mass may present with [[Symptom|symptoms]] caused by the [[Tumor|mass]] pressing against other [[Mediastinum|mediastinal structures]] or even without any [[Symptom|symptoms]]. On the basis of [[Computed tomography|cross sectional imaging]], [[mediastinum]] can be divided into 3 groups: [[Anterior mediastinum|Prevascular]], [[Middle mediastinum|visceral]] and [[Posterior mediastinum|paravertebral]]. | | The [[mediastinum]] is a non-delineated group of structures in the [[Thorax|thorax (chest)]], surrounded by [[loose connective tissue]]. It is the central [[Compartment (anatomy)|compartment]] of the [[thoracic cavity]]. It contains the [[heart]], the [[great vessels]] of the [[heart]], [[esophagus]], [[trachea]], [[thymus]], and [[Lymph node|lymph nodes]] of the [[Mediastinum|central chest]]. A wide variety of [[Mediastinal mass causes|diseases]] involving these organs can present as a mediastinal mass or widening of the [[mediastinum]] on [[imaging studies]]. Mediastinal widening is diagnosed by the [[mediastinum]] measuring greater than 8 cm in width on [[Chest x-ray|PA chest x-ray]]. The mediastinal mass may present with [[Symptom|symptoms]] caused by the [[Tumor|mass]] pressing against other [[Mediastinum|mediastinal structures]] or even without any [[Symptom|symptoms]]. On the basis of [[Computed tomography|cross sectional imaging]], [[mediastinum]] can be divided into 3 groups: [[Anterior mediastinum|Prevascular]], [[Middle mediastinum|visceral]] and [[Posterior mediastinum|paravertebral]]. |
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| ==Anatomy of mediastinum==
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| * The [[mediastinum]] lies between the [[Visceral pleura|right and left pleura]] in and near the [[Anatomical terms of location|median sagittal plane]] of the [[chest]].
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| * It extends from the [[sternum]] in front to the [[vertebral column]] behind, and contains all the [[Chest|thoracic]] [[viscera]] except the [[lungs]]. It may be divided for purposes of description into two parts:
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| ** '''Superior mediastinum:''' Above the upper level of the [[pericardium]], which is named the ''[[superior mediastinum]]'' with its [[superior]] limit at the [[Superior thoracic aperture|superior thoracic opening]] and its [[Anatomical terms of location|inferior]] limit at the plane from the [[sternal angle]] to the [[Thoracic vertebrae|disc of T4-T5]] (Plane of Ludwig)
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| ** '''Inferior mediastinum''': Below the upper level of the [[pericardium]]. This lower portion is again subdivided into three parts:
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| *** In front of the pericardium, the ''[[anterior mediastinum]]''
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| *** Containing the pericardium and its contents, the ''[[middle mediastinum]]''
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| *** Behind the pericardium, the ''[[posterior mediastinum]]''
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| *** It is surrounded by the [[Thoracic cavity|chest wall]] [[Anatomical terms of location|anteriorly]], the [[Lung|lungs]] [[Lateral|laterally]] and the [[Vertebral column|spine]] [[Anatomical terms of location|posteriorly]].
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| *** It is continuous with the [[loose connective tissue]] of the [[neck]], and extends [[Anatomical terms of location|inferiorly]] into the [[Diaphragm (anatomy)|diaphragm]].
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| * Note that clinical radiologists and anatomists categorize the mediastinum in slightly different ways.
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| * The International Thymic Malignancy Interest Group (ITMIG) has developed a new scheme to divide [[Mediastinum|mediastinal cavity]] on the basis of [[Computed tomography|cross sectional imaging]] for better [[Diagnosis|diagnostic]] and [[Therapy|therapeutic]] purposes.<ref name="CarterBenveniste2017">{{cite journal|last1=Carter|first1=Brett W.|last2=Benveniste|first2=Marcelo F.|last3=Madan|first3=Rachna|last4=Godoy|first4=Myrna C.|last5=de Groot|first5=Patricia M.|last6=Truong|first6=Mylene T.|last7=Rosado-de-Christenson|first7=Melissa L.|last8=Marom|first8=Edith M.|title=ITMIG Classification of Mediastinal Compartments and Multidisciplinary Approach to Mediastinal Masses|journal=RadioGraphics|volume=37|issue=2|year=2017|pages=413–436|issn=0271-5333|doi=10.1148/rg.2017160095}}</ref>
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| ** [[Anterior mediastinum|Prevascular (anterior)]]
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| ** [[Middle mediastinum|Visceral (middle)]]
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| ** [[Posterior mediastinum|Paravertebral (posterior)]]
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| {|
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| ! colspan="3" style="background:#4479BA; color: #FFFFFF;" align="center" + |'''<big>International Thymic Malignancy Interest Group (ITMIG) Classification of Mediastinum</big>'''
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| ! style="background: #4479BA; color: #FFFFFF; text-align: center;" |'''Compartments'''
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| ! style="background: #4479BA; color: #FFFFFF; text-align: center;" |'''Boundaries'''
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| ! style="background: #4479BA; color: #FFFFFF; text-align: center;" |'''Components'''
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| |-
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| | style="background: #DCDCDC; padding: 5px; text-align: center;" |'''Prevascular'''
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| | style="background: #F5F5F5; padding: 5px;" |
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| * '''Superior:''' [[Superior thoracic aperture|Thoracic inlet]]
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| * '''Inferior:''' [[Thoracic diaphragm|Diaphragm]]
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| * '''Anterior:''' [[Sternum]]
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| * '''Posterior:''' [[Anatomical terms of location|Anterior]] aspect of the [[pericardium]]
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| * '''Lateral:''' [[Parietal pleura|Parietal mediastinal pleura]]
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| | style="background: #F5F5F5; padding: 5px;" |
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| * [[Thymus]]
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| * [[Fat]]
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| * [[Lymph node|Lymph nodes]]
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| * [[Brachiocephalic vein|Left brachiocephalic vein]]
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| |-
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| | style="background: #DCDCDC; padding: 5px; text-align: center;" |'''Visceral'''
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| | style="background: #F5F5F5; padding: 5px;" |
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| * '''Superior:''' [[Superior thoracic aperture|Thoracic inlet]]
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| * '''Inferior:''' [[Thoracic diaphragm|Diaphragm]]
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| * '''Anterior:''' [[Anatomical terms of location|Posterior]] boundaries of the [[Anterior mediastinum|prevascular compartment]]
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| * '''Posterior:''' [[Vertical direction|Vertical]] line connecting a point on each [[Thoracic vertebrae|thoracic]] [[Body of vertebra|vertebral body]] 1 cm [[Anatomical terms of location|posterior]] to its origin
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| | style="background: #F5F5F5; padding: 5px;" |'''Non vascular:'''
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| * [[Trachea]]
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| * [[Carina of trachea|Carina]]
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| * [[Esophagus]]
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| * [[Lymph node|Lymph nodes]]
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| '''Vascular:'''
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| * [[Heart]]
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| * [[Ascending aorta|Ascending thoracic aorta]]
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| * [[Aortic arch]]
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| * [[Descending aorta|Descending thoracic aorta]]
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| * [[Superior vena cava]]
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| * [[Pulmonary arteries|Intrapericardial pulmonary arteries]]
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| * [[Thoracic duct]]
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| *
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| | style="background: #DCDCDC; padding: 5px; text-align: center;" |'''Paravertebral'''
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| | style="background: #F5F5F5; padding: 5px;" |
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| * '''Superior:''' [[Superior thoracic aperture|Thoracic inlet]]
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| * '''Inferior:''' [[Thoracic diaphragm|Diaphragm]]
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| * '''Anterior:''' [[Anatomical terms of location|Posterior]] boundaries of the [[Middle mediastinum|visceral compartment]]
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| * '''Posterolateral:''' Vertical line against the [[Anatomical terms of location|posterior]] margin of the [[Thoracic cavity|chest wall]] at the [[lateral]] margin of the [[Transverse processes|transverse process]] of the [[Thoracic vertebrae|thoracic spine]]
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| | style="background: #F5F5F5; padding: 5px;" |
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| * [[Thoracic vertebrae|Thoracic spine]]
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| * [[Prevertebral muscles|Paravertebral soft tissues]]
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| |-
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| | colspan="3" style="background:#DCDCDC;" align="left" + |<small>'''Adapted from [https://doi.org/10.1148/rg.2017160095 Radiographics]'''</small>
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| |}
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| ==References== | | ==References== |