視覚解剖学 Visual Anatomy

【境 界】

前方）胸骨　後方）胸椎　上方）胸郭上口　下方）横隔膜　左右）肺の縦隔胸膜

胸膜と縦隔	第8胸椎の高さの 胸郭の水平断面

 

以下は「Wikipedia」の解説文となる。

The mediastinum (from Medieval Latin mediastinus, "midway"[2]) 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, the trachea, the phrenicand cardiac nerves, the thoracic duct, the thymus and the lymph nodes of the central chest.

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 columnbehind, 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.[3][4][5]
• The inferior mediastinum from this level to the diaphragm. This lower part is subdivided into three regions, all relative to the pericardium – the anterior mediastinum being in front of the pericardium, the middle mediastinum contains the pericardium and its contents, and the posterior mediastinumbeing 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 middle (inferior) mediastinum.[6][page needed]
Superior mediastinum[edit]
The superior mediastinum is bounded:

• superiorly by the thoracic inlet, the upper opening of the thorax;
• inferiorly by the transverse thoracic plane;
• laterally by the pleurae;
• anteriorly by the manubrium of the sternum;
• posteriorly by the first four thoracic vertebral bodies.

Transverse-Thoracic plane

• The transverse 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.[3][4][5]

A number of structures occur at the level of the thoracic plane, which divides the superior and inferior mediastinum.
Inferior mediastinum
Anterior mediastinum
Is 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. superior and inferior sternopericardial ligaments

Middle mediastinum
Bounded: pericardial sac – It contains the vital organs and is classified into the serous and fibrous pericardium.
Posterior mediastinum
Is bounded:

• Anteriorly by (from above downwards): bifurcation of trachea; pulmonary vessels; fibrous pericardium and posterior sloping surface of diaphragm
• Inferiorly by the thoracic surface of the diaphragm (below);
• Superiorly by the transverse thoracic plane;
• Posteriorly 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).

A transverse section of the thorax, showing the contents of the middle and the posterior mediastinum.

 

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