it describes the mediastinum with respect to its different parts and different contents of it. some of the clinical aspects are also included.

1. Mediastinum
To MBBS 1st year
Dr. Laxman Khanal
Assistant professor, department of anatomy, BPKIHS
27-03-2018

2. At the end of the class students should be
able to:
• Define the “Mediastinum”.
• Differentiate between the divisions of the mediastinum.
• List the boundaries and contents of each division.
• Describe the relations between the important structures in each
division.

3. Introduction
• The mediastinum is the anatomic region medial to the pleural sacs.
• It extends from thoracic inlet to the diaphragm.
• All organs of the thorax are found in mediastinum except for lungs.
• Most important content is heart covered by pericardium.
• Thoracic plane divide the mediastinum into superior and inferior
mediastinum.
• Mediastinitis is the inflammation of loose connective tissue of the
mediastinum.
• Compression of mediastinal structures leads to mediastinal
syndrome.

4. Thoracic inlet or outlet ?

5. Thoracic inlet
Diaphragm
Superior
mediastinum
Inferior
mediastinum
Q Where does SVC lies?
a. Superior mediastinum
b. Inferior mediastinum
c. Both

6. T1
T12
Mediastinum
1. Superior mediastinum
2. Inferior mediastinum
a. Anterior mediastinum
b. Middle mediastinum
c. Posterior mediastinum
M
PC PC
PC +
heart

7. Superior mediastinum
• Muslces:
Sternohyoid,Sternothyroid & Longus colli
• Thymus
• Nerves:
Vagus nerve, Phrenic nerve
Left recurrent laryngeal nerve
• Veins:
Brachiocephalic veins+Upper half of SVC
• Artery:
Arch of aorta + its direct branches
• Tubes:
Trachea + Oesophagus
• Thoracic duct

8. T3 level T4 level
Superior mediastinum

9. Anterior mediastinum
Boundaries?
Contents:
• Sterno-pericardial ligaments
• Lowest part of thymus
• Lymph nodes
• Mediastinal branch of Int thoracic artery
Q.What is the root value of phrenic nerve?
C3, C4,C5

10. Middle mediastinum
Contents:
• Heart with pericardium
• Ascending aorta
• Bifurcation of trachea
• Pulmonary trunk and its division
• Lower half of SVC
• Rt/Lt pulmonary veins
• Phrenic nerve
• Deep cardiac plexus
All the vessels that go in & out the heart are
included in the middle mediastinum.

11. Posterior mediastinum
Contents:
• Descending aorta
• Azygous system
• Esophagus
• Thoracic duct
• Sympathetic trunks
• Vagus nerves
Q. Which cranial nerve is
the Vagus nerve?
10th

12. Phrenic
nerve
Vagus nerve
Middle
mediastinum
Posterior
mediastinum
+ = Superior mediastinum

13. Mediastinal shift:
 It is a clinical and radiological marker of significant importance.
 Indicators of mediastinal shift:
• Tracheal deviation (for upper mediastinal shift)
• Heart deviation (for lower mediastinal shift)
Deviation: To the opposite side (not always) of the lesion (like pleural effusion)
Normal chest radiograph

14. Mediastinal widening
Mediastinal widening is defined as a
mediastinum with a measured width
greater than 8 cm on chest radiograph.
 Mediastinum : chest width ratio is
greater than 0.25

15. Mediastinal syndrome:
Compression of the mediastinal structures by any mass give rise to the group
of signs and symptoms called as mediastinal syndrome.
Common causes are:
 Bronchogenic carcinoma
 Hodgkin lymphoma
 Aortic aneurysm