AN23.1-6 | Mediastinum — Summary & Reflection

REFLECT

Consider a patient with newly diagnosed lymphoma presenting with facial swelling, dilated neck and chest veins, and headache worsened by bending forward. Which mediastinal structure is compressed? What compartment is the tumour likely in? How would mediastinal anatomy guide the staging biopsy approach?

KEY TAKEAWAYS

Mediastinum — Key Points:

1. Divided into superior (above T4/T5) and inferior (anterior, middle, posterior)
2. Superior: thymus → brachiocephalic veins → aortic arch → trachea → oesophagus (A→P)
3. Posterior: oesophagus, descending aorta, azygos system, thoracic duct, sympathetic chains
4. Thoracic duct: enters T12 (right), crosses left at T5, drains into left subclavian vein
5. Oesophagus: 4 constrictions; T10 hiatus; dual blood supply → varices in portal hypertension
6. Vagus: right loops under subclavian artery; left loops under aortic arch (at ligamentum)
7. Phrenic: lateral to pericardium, anterior to hilum; C3,4,5 keep the diaphragm alive