Mediastinum

Question 1

1. Name the contents of the mediastinum
2. Describe the relations of the mediastinum (borders)
3. What are the anaesthetic conserns with a tumour in the anterior mediastinum?

Answer 1

1. Contains all the thoracic organs except the lungs:

Arise and remain in the mediastinum

Heart and pericardium

Thymus

Traverse the mediastinum

Oesophagus

Thoracic duct (enters the venous system at the junction of the left internal jugular and subclavian veins)

Arise in the mediastinum

Aorta

Aortic arch vessels

Bronchial tree

Pulmonary arteries

End in the mediastinum

Trachea

Inferior vena cava

Venous drainage of the head and neck

Pulmonary veins

Vagus nerves

Phrenic nerves

2. The mediastinum is bounded:

Anteriorly by the sternum

Posteriorly by the vertebral column

Superiorly by the thoracic inlet/root of the neck

Inferiorly by the diaphragm

Laterally by the pleurae and lungs

3. Tumours arising in the anterior mediastinum may compress the heart and trachea and anaesthetic management requires a specialist approach.

Unrecognised ant mediastinal masses are a rare cause of failed ventilation and cardiovascular collapse at induction.

Question 2

1. Describe the root the thorasic duct takes
2. Describe the structures at the right hilum and their relationships to eachother
3. Do the same for the left

Answer 2

1. The Thorasic duct recieves lymph trunks and ascends from L2 to the root of the neck. It passes through the diaphragm posterior to the oesophagus. It crosses to the left and out the thorasic inlet to the left common carotid and internal jugular venous system at the junction of the left subclavian and internal jugular.
2. Rt side:

The PA passes anteriorly to the right main bronchus and posterior and superiorly to the inferior pulmonary vein

3. Lt side:

The PA loops superiorly to the bronchus. The bronchus is posterior to the left superior pulmonary vein and superior to the left inferior pulmonary vein