What is the division of mediastinum, and what is the organizational structure contained in each division?

The mediastinum is divided into three types:

1, nine points method: anterior mediastinum: located in front of trachea, ascending aorta and heart, it is an inverted narrow triangular area; Mediastinum: equivalent to trachea, aortic arch, hilum and heart; Posterior mediastinum: the area behind the anterior margin of esophagus; Upper mediastinum: above the horizontal line from sternal angle to the lower edge of the fourth thoracic vertebra; Lower mediastinum: below the horizontal line from the fourth anterior costal end to the lower edge of the eighth thoracic vertebra; Mediastinum: located between the upper and lower mediastinum.

2. Four anatomical points: upper mediastinum: above the horizontal line from sternal angle to the lower edge of the fourth thoracic vertebra; Trachea is divided into anterior mediastinum and posterior mediastinum; Lower mediastinum: below the horizontal line from sternal angle to the lower edge of the fourth thoracic vertebra; Pericardia is bounded: the anterior mediastinum is in front of pericardium; Pericardia and trachea are mediastinum; Behind the pericardium is the posterior mediastinum (see Figure 5).

3. Trigonometry: The simplest classification method proposed by Shields in 1972. All mediastinum is divided from the thoracic inlet to the diaphragm. The anterior boundary of anterior mediastinum is the inner surface of sternum, and the posterior boundary is the anterior wall of pericardium and great vessels. The visceral mediastinal region is located in front of the posterior boundary of the anterior mediastinum and then in front of the vertebral body. The posterior mediastinum is the paravertebral mediastinal region, from the posterior part of the visceral mediastinal region to the costal angle.

Each partition contains tissue: in the upper mediastinum, the anterior organ is thymus, which is divided into two parts, the upper end can extend into the neck and the lower end can extend into the anterior mediastinum. Behind the thymus is the left innominate vein, which inclines from left to right. After connecting with the right innominate vein, this group is superior vena cava. Behind the superior vena cava are the ascending aorta, aortic arch and its branches. The pulmonary artery is under the aortic arch and divided into left and right pulmonary arteries.

The right pulmonary artery is behind the ascending aorta and the left pulmonary artery is before the descending aorta. The trachea is behind the ascending aorta and aortic arch. The aortic arch spans the front of the trachea and forms the descending aorta on its left side. Behind the trachea is the esophagus.

There are heart, great vessels, tracheal bifurcation, common bronchus, lymph nodes and their nearby lymph nodes, pericardium and phrenic nerves on both sides of pericardium in the middle mediastinum. There are bronchus, esophagus, azygos vein, hemiazygos vein, sympathetic trunk, descending aorta and thoracic duct in the posterior mediastinum.

Extended data:

The medical value of anatomy;

The human body structure is very fragile, and most organs have a lot of reserve capacity, which can function normally even if they are damaged. For example, the liver must be destroyed by more than 2/3 before serious damage can occur. If one lung is removed, as long as the other lung functions normally, people can survive.

Some organs can cause dysfunction as long as they are slightly damaged. For example, if a small amount of brain tissue is damaged during a stroke, the patient may not be able to speak, move his limbs or keep balance. A heart attack can damage the heart tissue, which may only slightly damage the heart's ability to pump blood, or may lead to death.

Diseases affect anatomical structures, and changes in anatomical structures can lead to diseases. Abnormal tissue hyperplasia, such as cancer, can directly destroy normal tissue or oppress normal tissue, causing damage. Another example is blocking the blood supply to the tissue, which can cause tissue necrosis (infarction) such as myocardial infarction or stroke (cerebral infarction).

Because of the close relationship between anatomy and disease, the method of examining the internal structure of the body has become the main means of disease diagnosis and treatment. The first major breakthrough was the discovery of X-ray, which enabled doctors to see the internal structure of the body and examine the internal organs without surgery.

Another important development is computed tomography (CT), which is a combination of X-ray and computer. CT scanning produces a detailed two-dimensional image of the internal structure of the body.

Other methods to generate images of internal structures include ultrasonic scanning, magnetic resonance imaging (MRI) based on atomic motion in magnetic field and radionuclide imaging technology. The method is to inject radioactive chemicals into the body for inspection. Compared with surgery, these tests are non-invasive and surgery is invasive.

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