1. Mediastinum
Dr. Sama ul Haque Dr Rania Gabr

2. Objectives
Define mediastinum.
Enlist the divisions of mediastinum.
Describe the boundaries and contents of mediastinum.

3. Lateral view of Thorax

4. Mediastinum Definition:
A median septum or median partition between the two pleural cavities.
It includes all the structures which lie in the intermediate compartments of the thoracic cavity

5. Boundaries of the Mediastinum
Superior boundary:
Superior thoracic aperture
Inferior boundary:
Diaphragm
Anterior boundary:
Sternum
Posterior boundary:
Bodies of vertebrae T1 to T12
Lateral boundaries:
Mediastinal parietal pleura
(left and right).

6. Divisions of Mediastinum
Superior mediastinum:
Above the imaginary plane between the sternal angle and the lower border of the 4th thoracic vertebra.

7. Divisions of Mediastinum
Inferior mediastinum:
Below the imaginary plane and it is further subdivided into:
a. Anterior mediastinum: Behind the body and
xiphoid process of the sternum and in front of
the middle mediastinum (pericardium).
b. Middle mediastinum: Contains pericardium,
heart and the roots of the great vessels.
c. Posterior mediastinum: lies behind the middle
mediastinum (the part that lies posterior to the
pericardium and anterior to the bodies of
vertebrae T5 to T12).

8. Mediastinum

9. Divisions of Mediastinum

10. Contents of the Superior Mediastinum
From post. to ant.:
Esophagus
Trachea
Arch of Aorta: and its 3 brs:
1- Brachiocephalic artery
2- Left common carotid artery
3- Left subclavian artery
Brachiocephalic veins
Superior vena cava
Remains of Thymus
Nerves:
Phrenic nerves: rt and lt
Vagus nerves: rt and lt
Left recurrent laryngeal nerve
Sympathetic trunk
Others
Lymph nodes and Thoracic duct

11. Superior Mediastinum

12. Superior Mediastinum

13. Inferior Mediastinum

14. Inferior Mediastinum

15. Inferior Mediastinum (Lateral view)

16. Anterior Mediastinum Sternopericardial ligaments Lymph nodes
Remains of thymus

17. Middle Mediastinum (Lateral view)
Pericardium
Heart
Arteries: Roots of the great vessels: aorta and pulmonary art.
Veins: lower half of superior vena cava, terminations of inferior vena cava & pulmonary veins
Nerves: Phrenic nerves
Bifurcation of trachea
Lymph nodes

18. Posterior Mediastinum
Descending thoracic Aorta
Esophagus: most anterior
Thoracic duct
Azygous vein
Hemiazygous vein
Vagus nerves
Rt and lt Sympathetic trunks and their brs: splanchnic nerves
Lymph nodes

19. Posterior Mediastinum

20. Posterior Mediastinum

21. Posterior Mediastinum

22. Posterior Mediastinum

23. Positional changes of Mediastinum