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the part of the thoracic cavity between the lungs that contains the heart and aorta and esophagus and trachea and thymus

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/08/13 23:38:09」(JST)

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The mediastinum is an undelineated group of structures in the thorax, surrounded by loose connective tissue. It is the central compartment of the thoracic cavity. It contains the heart, the great vessels of the heart, the esophagus, the trachea, the phrenic nerve, the cardiac nerve, the thoracic duct, the thymus, and the lymph nodes of the central chest.

Structure

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 aperture and its inferior limit at the plane from the sternal angle to the disc of T4-T5 (Plane of Ludwig at Angle of Louis);
and a lower portion, below the upper level of the pericardium. This lower portion is 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.

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.^[1]^{[page needed]}

Anterior mediastinum Bounded: Laterally by the pleurae Posteriorly by the pericardium Anteriorly by the sternum, the left transversus thoracis and the fifth, sixth, and seventh left costal cartilages Contents A quantity of loose areolar tissue Some lymphatic vessels which ascend from the convex surface of the liver Two or three anterior mediastinal lymph nodes The small mediastinal branches of the internal thoracic artery Thymus (involuted in adults)	Posterior mediastinum It is bounded: anteriorly by the pericardium (in front of) inferiorly by the thoracic surface of the diaphragm (below). superiorly by the transverse thoracic plane (above). This plane is marked by an imaginary line travelling through the manubriosternal joint to the dividing line between the fourth and fifth thoracic vertebrae. posteriorally by the bodies of the vertebral column from the lower border of the fifth to the twelfth thoracic vertebra (behind). laterally by the mediastinal pleura (on either side) Contents artery thoracic part of the descending aorta veins azygos vein the hemiazygos vein and the accessory hemiazygos vein nerves vagus nerve splanchnic nerves sympathetic chain esophagus thoracic duct some lymph glands
Middle mediastinum Contents the heart enclosed in the pericardium the ascending aorta the lower half of the superior vena cava with the azygos vein opening into it the bifurcation of the trachea and the two bronchi the pulmonary artery dividing into its two branches the right and left pulmonary veins the phrenic nerves some bronchial lymphatic glands pericardiocophrenic vessels	Superior mediastinum The superior mediastinum is bounded by: superiorly by the thoracic inlet, the upper opening of the thorax inferiorly by the transverse thoracic plane, a slightly oblique plane passing posteriorly from the junction of the manubrium and body of the sternum (sternal angle of Louis) to the junction of the 4th and 5th thoracic vertebra (see also thoracic plane) laterally by the pleurae anteriorly by the manubrium of the sternum posteriorly by the first four thoracic vertebral bodies Contents muscles origins of the Sternohyoidei and Sternothyreoidei lower ends of the Longi colli arteries aortic arch brachiocephalic artery thoracic portions of the left common carotid and the left subclavian veins brachiocephalic veins and upper half of the superior vena cava left highest intercostal vein nerves vagus nerve cardiac nerve superficial and deep cardiac plexuses phrenic nerve left recurrent laryngeal nerve trachea esophagus thoracic duct remains of the thymus some lymph glands anterior longitudinal ligament

Clinical significance

The mediastinum is frequently the site of involvement of various tumors:

Anterior mediastinum: substernal thyroid goiters, lymphoma, thymoma and teratoma.
Middle mediastinum: lymphadenopathy, metastatic disease such as from small cell carcinoma from the lung.
Posterior mediastinum: Neurogenic tumors, either from the nerve sheath (mostly benign) or elsewhence (mostly malignant).

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

There are many diseases that can present with a widened mediastinum (usually found via a chest x-ray). The most common ones are aortic unfolding, traumatic aortic rupture, thoracic aortic aneurysm, and traumatic thoracic vertebral fracture. With infectious etiologies, a widened mediastinum is a classic hallmark sign of anthrax infection.

References

This article incorporates text from a public domain edition of Gray's Anatomy.

^ Goodman, Lawrence. Felson's Principles of Chest Roentgenology.

Additional images

A transverse section of the thorax, showing the contents of the middle and the posterior mediastinum. The pleural and pericardial cavities are exaggerated since normally there is no space between parietal and visceral pleura and between pericardium and heart.

External links

Look up mediastinum in Wiktionary, the free dictionary.

1691353147 at GPnotebook
Anatomy figure: 21:01-03 at Human Anatomy Online, SUNY Downstate Medical Center - "Divisions of the mediastinum."
Anatomy figure: 21:02-03 at Human Anatomy Online, SUNY Downstate Medical Center - "The anatomical divisions of the inferior mediastinum."
thoraxlesson3 at The Anatomy Lesson by Wesley Norman (Georgetown University) - "Subdivisions of the Thoracic Cavity"
mediastinum at eMedicine Dictionary
Anatomy at MUN thorax/media

UpToDate Contents

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1. 縦隔腫瘤の評価 evaluation of mediastinal masses
2. 縦隔リンパ節腫脹の外科的マネージメント surgical management of mediastinal lymphadenopathy
3. 胸腺神経内分泌（カルチノイド）腫瘍 thymic neuroendocrine carcinoid tumors
4. 前部縦隔の腫瘤性病変 anterior mediastinal mass lesions
5. 縦隔における内視鏡的超音波ガイド下穿刺吸引 endoscopic ultrasound guided fine needle aspiration in the mediastinum

English Journal

Report of six kidney disease-associated Castleman's disease cases.

Sui Y, Zhao D.
Clinical nephrology.Clin Nephrol.2015 Dec;84 (2015)(12):344-352.
Castleman's disease (CD) is an uncommon, benign, non-neoplastic, lymphoproliferative disease of uncertain etiology. Here, we report 6 cases of kidney disease-associated CD in China. All patients exhibited multicentric CD (MCD) with involvement of the mediastinum, neck, bilateral axillary, and bilate
PMID 26445003

Myeloid Sarcoma: An Unusual Case of Mediastinal Mass and Malignant Pleural Effusion with Review of Literature.

Sahu KK1, Tyagi R2, Law AD1, Khadwal A1, Prakash G1, Rajwanshi A2, Varma SC1, Malhotra P1.
Indian journal of hematology & blood transfusion : an official journal of Indian Society of Hematology and Blood Transfusion.Indian J Hematol Blood Transfus.2015 Dec;31(4):466-71. doi: 10.1007/s12288-015-0536-z. Epub 2015 Apr 1.
Myeloid sarcoma is an extramedullary tumor seen most commonly in patients with acute myeloid leukemia and less frequently in chronic myeloid leukemia, myelodysplastic syndrome and rarely, in an isolated form without any other underlying malignancy. Malignant pleural effusion in hematological maligna
PMID 26306072

Mediastinal Mature Teratoma With Malignant Carcinomatous Transformation (Somatic-Type Malignancy) With Metastatic Course.

Habougit C1, Yvorel V1, Sulaiman A1, Hag B2, Péoc'h M1, Forest F3.
International journal of surgical pathology.Int J Surg Pathol.2015 Dec;23(8):682-4. doi: 10.1177/1066896915591583. Epub 2015 Jun 24.
We report the case of a 76-year-old patient presenting with an anterior mediastinal heterogeneous mass. Surgical biopsy revealed a solid and cystic lesion filled with hair. Pathological examination showed an atypical papillary epithelial lining without other germ cell tumor or immature teratoma asso
PMID 26113666

Japanese Journal

臨床報告非開胸頸部襟状切開アプローチ手術で摘出した,頸部から縦隔に進展する副甲状腺胞の2例

上林孝豊,鈴木卓,藤田葉子
臨床外科 67(10), 1338-1342, 2012-10
NAID 40019441253

Esophageal Cancer Initially Thought to be Accompanied by a Solitary Metastasis to an Intrathoracic Paraaortic Lymph Node

Horio Takuya,Ogata Sho,Tsujimoto Hironori,Akase Takayoshi,Takahata Risa,Yaguchi Yoshihisa,Maehara Tadaaki,Hase Kazuo
Acta Medica Okayama 66(5), 417-421, 2012-10
… We present here an intrathoracic mid-esophageal cancer case in which an accompanying solitary retroaortic mass was found within the posterior mediastinum by integrated positron emission tomography/computed tomography. …
NAID 120004873440

症例 89歳に手術を行った原発性肺多形癌の一例

松原裕,立石雅宏,奥山稔朗 [他]
福岡医学雑誌 103(9), 182-185, 2012-09-25
… FDG-PET seemed to show hilar and mediastinum lymph nodes metastasis. … Hilar and mediastinum lymph nodes dissection was added. …
NAID 40019478953