Lecture 11

Question 1

Describe the mediastinum?

Answer 1

It extends from the thoracic inlet to the diaphragm between the lungs. Lateral boundaries formed by the pleura which surrounds the mediastinum except for short segments anterior and posterior. Contains the heart and forms a conduit for the great vessels. Also contains lymph nodes, thymus, neural tissue and thyroid.

Question 2

How do we investigate the mediastinum?

Answer 2

Chest XRAY, angiogram. The chest XRAy is the most important assessment of the mediastinum. The left border - LV and the right border - RA. The bump at the superior of the mediastinum is the aortic arch. The little bump above the RA is the ascending aorta. the hallmark of the mediastinum is the azyoesphogeal recess. You won’t see the SVC as it is in with the fatty tissue of the mediastinum, thus you will not get a nice edge/outline of the lung. Don’t see an IVC on a normal chest X-ray either.

Question 3

Describe a conventional left lateral film?

Answer 3

This is where the left side of the patient is always against the left side of the box, and the right side is against the source of X-ray. Thus the right side of the chest will be magnified. The cardiac border of the RV is the anterior part. The LV is just above the diaphragm. You can see the IVC on the lateral film.

Question 4

Describe Mediastinal divisions?

Answer 4

Anatomy put the heart in the middle mediastinum. If you can identify where something is, then you re 90% on the way to identifying what it is. In pathology it helps to understand which of these structures is most likely to go wrong. It is divided into Superior and Inferior (which is divided into Anterior, Middle and Posterior) mediastinum.

Question 5

What is the azygoesophageal recess?

Answer 5

This is the region below the azygos vein arch in which the right lung intrudes into the mediastinum between the heart and vertebral column, bordered on the left by the oesophagus. Radiologically, on a frontal chest image, the vertical interface between the right lung and the oesophagus.

Question 6

Describe the superior mediastinum?

Answer 6

It is above the sternal notch. On the lateral film the superior mediastinum goes between the sternal notch and posterior to T4.

Question 7

What is in the superior mediastinum?

Answer 7

Thyroid, trachea and oesophagus.

Question 8

What can go wrong in the superior mediastinum?

Answer 8

Thyroid - goitre.

Question 9

What is in the anterior mediastinum?

Answer 9

Thymus.

Question 10

What can go wrong in the anterior mediastinum?

Answer 10

Thyroid, Thymoma (most common neoplasm in your 40s and 50s), Lymphoma (most common of these diseases) and Teratoma (Four Terrible T’s).

Question 11

What is in the middle mediastinum?

Answer 11

Heart, trachea, oesophagus and great vessels.

Question 12

What can go wrong in the middle mediastinum?

Answer 12

Cardiac and vascular lesions, oesophageal abnormalities, lymphadenopathy (lymphoma) and bronchogenic cysts.

Question 13

What is in the posterior mediastinum?

Answer 13

Nerves; intercostal, sympathetic and parasympathetic.

Question 14

What can go wrong in the posterior mediastinum?

Answer 14

Neurogenic tumours. 90-95% of abnormal masses are neurogenic tumours.

Question 15

Why don’t we see the oesophagus edge on the other side (left side)?

Answer 15

There is too much fatty tissue in the mediastinum.

Question 16

What does the azygos vein drain?

Answer 16

Vertebral system.

Question 17

What is a marker for the middle mediastinum?

Answer 17

The azygoesophageal recess - air-interface which shows pouch of air.

Question 18

What are the pathologies of the mediastinum?

Answer 18

Vascular - aortic dissection, aneurysms. Can affect anywhere int he mediastinum.
Trauma - line placement or car accidents.
Neoplasms - some of the tumours are more common in posterior and some more so anteriorly.
Congenital cysts - bronchogenic.
Involvement from adjacent structures e.g. spine, lung Ca.

Question 19

Describe trauma to the mediastinum?

Answer 19

Line placement.
Blunt trauma.
Barotrauma - occurs when people go diving.
Oesophageal rupture - yardy at 21st. Oesophagus closes at both ends (50% mortality rate).

Question 20

What is an aortic transection?

Answer 20

Part is stabilised by subclavian artery and the other part is more mobile (descending). The point at which the descending aorta is stabilised to the part where it isn’t, it keeps moving and it could sheer off (start bleeding to the pleura - go to OR).

Question 21

Describe a neoplasm in the superior mediastinum?

Answer 21

It is a benign neoplasm in the thyroid itself (Goitre). This is the most common one. It is usually form inadequate iodine.

Question 22

Describe a neoplasm in the anterior mediastinum?

Answer 22

The terrible T’s. (terrible) Lymphoma, Thyroid (Goitre), Teratomas (and other germ cell tumours), Thymic tumours.

Question 23

Describe Haital hernia?

Answer 23

Occupy the lower part of the middle mediastinum.

Question 24

Describe cardiomegaly - CHF?

Answer 24

Cardiomegaly - usually not always vascular redistribution-azygos (gets bigger). Interstitial: peribronchial thickening, kersey B lines. Pulmonary oedema. Pleural effusions - R>L. The heart is big. Symmetry is a marker for CHF (congestive heart failure).

Question 25

Describe AP film?

Answer 25

Where the patient can’t stand up so the film is anterior-posterior -> this will magnetise the size of the heart. The only way to tell if it is an AP is the position of the scapulae.