clinically oriented anatomy Mediastinum.pptx

mediastinum anatomy

1. MEDIASTINUM Dr. Soran M Karim

2. References Clinical anatomy by regions, 10 th edition, Richard Snell's; pages 193-221 Netters atlas with clinical correlations 5 th edition, pages 200-216.

3. Mediastinum: The mediastinum is located in the middle of the thoracic cavity. The main contents include the heart, trachea, esophagus, great vessels, and thymus gland. The mediastinum is lined mainly by the parietal pleura. The mediastinum also contains another cavity called the pericardial cavity. The pericardial cavity surrounds the heart and roots of the great vessels.  

4. Sub divisions Divided in superior and inferior divisions by imaginary line passing from the sternal angle anteriorly to the lower border of the 4 th thoracic vertebrae. The inferior mediastinum is further subdivided into the middle mediastinum, which consists of the pericardium and heart, the anterior mediastinum , which is a space between the pericardium and the sternum and the posterior mediastinum, which lies between the pericardium and the vertebral column.

5. Superior mediastinum The superior mediastinum is the region sandwiched between the pleural sac on each side above an imaginary line from the angle of Louis in front to the fourth/fifth thoracic  intervertebral disc  behind. Its important contents are the oesophagus , trachea, great veins,  aortic arch  and its branches, the vagus , phrenic and left  recurrent laryngeal nerves , the upper part of the  thoracic duct  and the thymus gland.

6. Inferior mediastinum Inferior mediastinum  – extends downwards, terminating at the diaphragm. It is further subdivided into the anterior mediastinum, middle mediastinum and posterior mediastinum.

7. POSTERIOR MEDIASTINUM CONTENTS: Esophagus (most anterior structure) Thoracic duct Right & left vagus Descending aorta Azygos & hemiazygos veins Right & left sympathetic trunks & their branches (splanchnic nerves) Lymph nodes

8. Clinical correlations Mediastinitis Deep infection of the neck spread readily into the thorax, producing a mediastinitis . Penetrating wounds of the chest involving the esophagus may produce a mediastinitis .

9. Clinical correlations; cont. Deflection of Mediastinum If air enters the pleural cavity (a condition called pneumothorax ), the lung on that side immediately collapses and the mediastinum is displaced to the opposite side. patient’s being breathless and in a state of shock; on examination , the trachea and the heart are found to be displaced to the opposite side

10. Clinical correlations; cont Mediastinal Tumors or Cysts Enlargement of mediastinal tumor may compress the left recurrent laryngeal nerve, producing paralysis of the left vocal fold. An expanding cyst or tumor can partially occlude the superior vena cava, causing severe congestion of the veins of the upper part of the body. Other pressure effects can be seen on the sympathetic trunks, phrenic nerves, and sometimes the trachea, main bronchi, and esophagus.

11. Clinical correlations; cont Mediastinoscopy diagnostic procedure by which tracheobronchial lymph nodes are obtained without opening the pleural cavities. A small incision is made in the midline in the neck just above the suprasternal notch, and the superior mediastinum is explored down to the region of the bifurcation of the trachea. The procedure can be used to determine the diagnosis and degree of spread of carcinoma of the bronchus.

12. Summary Mediastinum: definition Boundaries and extensions Sub divisions Contents

13. Upcoming lecture; next week The heart and pericardium Clinical anatomy by region Chapter 4 ; pages 192-217